Store partial derivative values in sw_span structure.

Implemented DDX and DDY fragment program instructions (whew!)
Not fully tested yet.

5 files changed, 548 insertions, 285 deletions

diff --git a/src/mesa/swrast/s_context.h b/src/mesa/swrast/s_context.h
index 91063f0ef8..219e002990 100644
--- a/src/mesa/swrast/s_context.h
+++ b/src/mesa/swrast/s_context.h
@@ -1,4 +1,4 @@
-/* $Id: s_context.h,v 1.25 2003/02/28 15:09:02 brianp Exp $ */
+/* $Id: s_context.h,v 1.26 2003/03/16 22:02:36 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -133,6 +133,9 @@ struct sw_span {
     */
    GLuint interpMask;
 
+   /* For horizontal spans, step is the partial derivative wrt X.
+    * For lines, step is the delta from one fragment to the next.
+    */
 #if CHAN_TYPE == GL_FLOAT
    GLfloat red, redStep;
    GLfloat green, greenStep;
@@ -158,6 +161,18 @@ struct sw_span {
    GLfloat texStepY[MAX_TEXTURE_COORD_UNITS][4];
    GLfixed intTex[2], intTexStep[2];  /* s, t only */
 
+   /* partial derivatives wrt X and Y. */
+   GLfloat dzdx, dzdy;
+   GLfloat w, dwdx, dwdy;
+   GLfloat drdx, drdy;
+   GLfloat dgdx, dgdy;
+   GLfloat dbdx, dbdy;
+   GLfloat dadx, dady;
+   GLfloat dsrdx, dsrdy;
+   GLfloat dsgdx, dsgdy;
+   GLfloat dsbdx, dsbdy;
+   GLfloat dfogdx, dfogdy;
+
    /**
     * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
     * which of the fragment arrays in the span_arrays struct are relevant.
diff --git a/src/mesa/swrast/s_nvfragprog.c b/src/mesa/swrast/s_nvfragprog.c
index b139b8cc55..cd3f307f97 100644
--- a/src/mesa/swrast/s_nvfragprog.c
+++ b/src/mesa/swrast/s_nvfragprog.c
@@ -1,4 +1,4 @@
-/* $Id: s_nvfragprog.c,v 1.8 2003/03/15 17:33:27 brianp Exp $ */
+/* $Id: s_nvfragprog.c,v 1.9 2003/03/16 22:02:37 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -42,7 +42,7 @@
  */
 static void
 fetch_texel( GLcontext *ctx, const GLfloat texcoord[4], GLuint unit,
-             GLuint targetBit, GLfloat color[4] )
+             GLfloat color[4] )
 {
    const GLfloat *lambda = NULL;
    GLchan rgba[4];
@@ -59,12 +59,13 @@ fetch_texel( GLcontext *ctx, const GLfloat texcoord[4], GLuint unit,
 
 
 /**
- * Fetch a texel w/ partial derivatives.
+ * Fetch a texel with the given partial derivatives to compute a level
+ * of detail in the mipmap.
  */
 static void
 fetch_texel_deriv( GLcontext *ctx, const GLfloat texcoord[4],
                    const GLfloat texdx[4], const GLfloat texdy[4],
-                   GLuint unit, GLuint targetBit, GLfloat color[4] )
+                   GLuint unit, GLfloat color[4] )
 {
    SWcontext *swrast = SWRAST_CONTEXT(ctx);
    const struct gl_texture_object *texObj = ctx->Texture.Unit[unit]._Current;
@@ -100,20 +101,131 @@ fetch_vector4( const struct fp_src_register *source,
                const struct fp_machine *machine,
                GLfloat result[4] )
 {
-   const GLfloat *src;
-
-   /*
-   if (source->RelAddr) {
-      GLint reg = source->Register + machine->AddressReg;
-      if (reg < VP_PROG_REG_START || reg > VP_PROG_REG_END)
-         src = zero;
-      else
-         src = machine->Registers[reg];
+   const GLfloat *src = machine->Registers[source->Register];
+
+   result[0] = src[source->Swizzle[0]];
+   result[1] = src[source->Swizzle[1]];
+   result[2] = src[source->Swizzle[2]];
+   result[3] = src[source->Swizzle[3]];
+
+   if (source->NegateBase) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
    }
-   else
-   */
+   if (source->Abs) {
+      result[0] = FABSF(result[0]);
+      result[1] = FABSF(result[1]);
+      result[2] = FABSF(result[2]);
+      result[3] = FABSF(result[3]);
+   }
+   if (source->NegateAbs) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
+   }
+}
 
-   src = machine->Registers[source->Register];
+
+/**
+ * Fetch the derivative with respect to X for the given register.
+ * \return GL_TRUE if it was easily computed or GL_FALSE if we
+ * need to execute another instance of the program (ugh)!
+ */
+static GLboolean
+fetch_vector4_deriv( const struct fp_src_register *source,
+                     const struct sw_span *span,
+                     char xOrY, GLfloat result[4] )
+{
+   GLfloat src[4];
+
+   ASSERT(xOrY == 'X' || xOrY == 'Y');
+
+   switch (source->Register) {
+   case FRAG_ATTRIB_WPOS:
+      if (xOrY == 'X') {
+         src[0] = 1.0;
+         src[1] = 0.0;
+         src[2] = span->dzdx;
+         src[3] = span->dwdx;
+      }
+      else {
+         src[0] = 0.0;
+         src[1] = 1.0;
+         src[2] = span->dzdy;
+         src[3] = span->dwdy;
+      }
+      break;
+   case FRAG_ATTRIB_COL0:
+      if (xOrY == 'X') {
+         src[0] = span->drdx * (1.0F / CHAN_MAXF);
+         src[1] = span->dgdx * (1.0F / CHAN_MAXF);
+         src[2] = span->dbdx * (1.0F / CHAN_MAXF);
+         src[3] = span->dadx * (1.0F / CHAN_MAXF);
+      }
+      else {
+         src[0] = span->drdy * (1.0F / CHAN_MAXF);
+         src[1] = span->dgdy * (1.0F / CHAN_MAXF);
+         src[2] = span->dbdy * (1.0F / CHAN_MAXF);
+         src[3] = span->dady * (1.0F / CHAN_MAXF);
+      }
+      break;
+   case FRAG_ATTRIB_COL1:
+      if (xOrY == 'X') {
+         src[0] = span->dsrdx * (1.0F / CHAN_MAXF);
+         src[1] = span->dsgdx * (1.0F / CHAN_MAXF);
+         src[2] = span->dsbdx * (1.0F / CHAN_MAXF);
+         src[3] = 0.0; /* XXX need this */
+      }
+      else {
+         src[0] = span->dsrdy * (1.0F / CHAN_MAXF);
+         src[1] = span->dsgdy * (1.0F / CHAN_MAXF);
+         src[2] = span->dsbdy * (1.0F / CHAN_MAXF);
+         src[3] = 0.0; /* XXX need this */
+      }
+      break;
+   case FRAG_ATTRIB_FOGC:
+      if (xOrY == 'X') {
+         src[0] = span->dfogdx;
+         src[1] = 0.0;
+         src[2] = 0.0;
+         src[3] = 0.0;
+      }
+      else {
+         src[0] = span->dfogdy;
+         src[1] = 0.0;
+         src[2] = 0.0;
+         src[3] = 0.0;
+      }
+      break;
+   case FRAG_ATTRIB_TEX0:
+   case FRAG_ATTRIB_TEX1:
+   case FRAG_ATTRIB_TEX2:
+   case FRAG_ATTRIB_TEX3:
+   case FRAG_ATTRIB_TEX4:
+   case FRAG_ATTRIB_TEX5:
+   case FRAG_ATTRIB_TEX6:
+   case FRAG_ATTRIB_TEX7:
+      if (xOrY == 'X') {
+         const GLuint u = source->Register - FRAG_ATTRIB_TEX0;
+         src[0] = span->texStepX[u][0] * (1.0F / CHAN_MAXF);
+         src[1] = span->texStepX[u][1] * (1.0F / CHAN_MAXF);
+         src[2] = span->texStepX[u][2] * (1.0F / CHAN_MAXF);
+         src[3] = span->texStepX[u][3] * (1.0F / CHAN_MAXF);
+      }
+      else {
+         const GLuint u = source->Register - FRAG_ATTRIB_TEX0;
+         src[0] = span->texStepY[u][0] * (1.0F / CHAN_MAXF);
+         src[1] = span->texStepY[u][1] * (1.0F / CHAN_MAXF);
+         src[2] = span->texStepY[u][2] * (1.0F / CHAN_MAXF);
+         src[3] = span->texStepY[u][3] * (1.0F / CHAN_MAXF);
+      }
+      break;
+   default:
+      return GL_FALSE;
+   }
 
    result[0] = src[source->Swizzle[0]];
    result[1] = src[source->Swizzle[1]];
@@ -138,6 +250,7 @@ fetch_vector4( const struct fp_src_register *source,
       result[2] = -result[2];
       result[3] = -result[3];
    }
+   return GL_TRUE;
 }
 
 
@@ -262,18 +375,122 @@ store_vector4( const struct fp_instruction *inst,
 
 
 /**
+ * Initialize a new machine state instance from an existing one, adding
+ * the partial derivatives onto the input registers.
+ * Used to implement DDX and DDY instructions in non-trivial cases.
+ */
+static void
+init_machine_deriv( GLcontext *ctx,
+                    const struct fp_machine *machine,
+                    const struct fragment_program *program,
+                    const struct sw_span *span, char xOrY,
+                    struct fp_machine *dMachine )
+{
+   GLuint u;
+
+   ASSERT(xOrY == 'X' || xOrY == 'Y');
+
+   /* copy existing machine */
+   _mesa_memcpy(dMachine, machine, sizeof(struct fp_machine));
+
+   /* Clear temporary registers */
+   _mesa_bzero(machine->Registers + FP_TEMP_REG_START,
+               MAX_NV_FRAGMENT_PROGRAM_TEMPS * 4 * sizeof(GLfloat));
+
+   /* Add derivatives */
+   if (program->InputsRead & (1 << FRAG_ATTRIB_WPOS)) {
+      GLfloat *wpos = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_WPOS];
+      if (xOrY == 'X') {
+         wpos[0] += 1.0F;
+         wpos[1] += 0.0F;
+         wpos[2] += span->dzdx;
+         wpos[3] += span->dwdx;
+      }
+      else {
+         wpos[0] += 0.0F;
+         wpos[1] += 1.0F;
+         wpos[2] += span->dzdy;
+         wpos[3] += span->dwdy;
+      }
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_COL0)) {
+      GLfloat *col0 = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_COL0];
+      if (xOrY == 'X') {
+         col0[0] += span->drdx * (1.0F / CHAN_MAXF);
+         col0[1] += span->dgdx * (1.0F / CHAN_MAXF);
+         col0[2] += span->dbdx * (1.0F / CHAN_MAXF);
+         col0[3] += span->dadx * (1.0F / CHAN_MAXF);
+      }
+      else {
+         col0[0] += span->drdy * (1.0F / CHAN_MAXF);
+         col0[1] += span->dgdy * (1.0F / CHAN_MAXF);
+         col0[2] += span->dbdy * (1.0F / CHAN_MAXF);
+         col0[3] += span->dady * (1.0F / CHAN_MAXF);
+      }
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_COL1)) {
+      GLfloat *col1 = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_COL1];
+      if (xOrY == 'X') {
+         col1[0] += span->dsrdx * (1.0F / CHAN_MAXF);
+         col1[1] += span->dsgdx * (1.0F / CHAN_MAXF);
+         col1[2] += span->dsbdx * (1.0F / CHAN_MAXF);
+         col1[3] += 0.0; /*XXX fix */
+      }
+      else {
+         col1[0] += span->dsrdy * (1.0F / CHAN_MAXF);
+         col1[1] += span->dsgdy * (1.0F / CHAN_MAXF);
+         col1[2] += span->dsbdy * (1.0F / CHAN_MAXF);
+         col1[3] += 0.0; /*XXX fix */
+      }
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_FOGC)) {
+      GLfloat *fogc = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_FOGC];
+      if (xOrY == 'X') {
+         fogc[0] += span->dfogdx;
+      }
+      else {
+         fogc[0] += span->dfogdy;
+      }
+   }
+   for (u = 0; u < ctx->Const.MaxTextureCoordUnits; u++) {
+      if (program->InputsRead & (1 << (FRAG_ATTRIB_TEX0 + u))) {
+         GLfloat *tex = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_TEX0+u];
+         if (xOrY == 'X') {
+            tex[0] += span->texStepX[u][0];
+            tex[1] += span->texStepX[u][1];
+            tex[2] += span->texStepX[u][2];
+            tex[3] += span->texStepX[u][3];
+         }
+         else {
+            tex[0] += span->texStepY[u][0];
+            tex[1] += span->texStepY[u][1];
+            tex[2] += span->texStepY[u][2];
+            tex[3] += span->texStepY[u][3];
+         }
+      }
+   }
+}
+
+
+/**
  * Execute the given vertex program.
  * NOTE: we do everything in single-precision floating point; we don't
  * currently observe the single/half/fixed-precision qualifiers.
+ * \param ctx - rendering context
+ * \param program - the fragment program to execute
+ * \param machine - machine state (register file)
+ * \param maxInst - max number of instructions to execute
  * \return GL_TRUE if program completed or GL_FALSE if program executed KIL.
  */
 static GLboolean
-execute_program(GLcontext *ctx, const struct fragment_program *program)
+execute_program( GLcontext *ctx,
+                 const struct fragment_program *program, GLuint maxInst,
+                 struct fp_machine *machine, const struct sw_span *span )
 {
-   struct fp_machine *machine = &ctx->FragmentProgram.Machine;
-   const struct fp_instruction *inst;
+   GLuint pc = 0;
 
-   for (inst = program->Instructions; inst->Opcode != FP_OPCODE_END; inst++) {
+   for (pc = 0; pc < maxInst; pc++) {
+      const struct fp_instruction *inst = program->Instructions + pc;
       switch (inst->Opcode) {
          case FP_OPCODE_ADD:
             {
@@ -297,32 +514,42 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
             break;
          case FP_OPCODE_DDX: /* Partial derivative with respect to X */
             {
-               GLfloat a[4], result[4];
-               fetch_vector4( &inst->SrcReg[0], machine, a );
-               /* XXX - UGH! this is going to be a mess to implement!
-                * If we need the partial derivative of a texture coord
-                * or color, that's not too bad, but for an arbitrary register
-                * this will require a recursive solution.  That is, we'll have
-                * to run another instance of this program with WPOS.x or .y
-                * incremented by one, stopping at the preceeding instruction.
-                * Then, read the register from that other instance and compute
-                * the difference.  Yuck!
-                */
-               result[0] = 0; /* XXX fix */
-               result[1] = 0;
-               result[2] = 0;
-               result[3] = 0;
+               GLfloat a[4], aNext[4], result[4];
+               struct fp_machine dMachine;
+               if (!fetch_vector4_deriv(&inst->SrcReg[0], span, 'X', result)) {
+                  /* This is tricky.  Make a copy of the current machine state,
+                   * increment the input registers by the dx or dy partial
+                   * derivatives, then re-execute the program up to the
+                   * preceeding instruction, then fetch the source register.
+                   * Finally, find the difference in the register values for
+                   * the original and derivative runs.
+                   */
+                  init_machine_deriv(ctx, machine, program, span,
+                                     'X', &dMachine);
+                  execute_program(ctx, program, pc, &dMachine, span);
+                  fetch_vector4( &inst->SrcReg[0], &dMachine, aNext );
+                  result[0] = aNext[0] - a[0];
+                  result[1] = aNext[1] - a[1];
+                  result[2] = aNext[2] - a[2];
+                  result[3] = aNext[3] - a[3];
+               }
                store_vector4( inst, machine, result );
             }
             break;
          case FP_OPCODE_DDY: /* Partial derivative with respect to Y */
             {
-               GLfloat a[4], result[4];
-               fetch_vector4( &inst->SrcReg[0], machine, a );
-               result[0] = 0; /* XXX fix */
-               result[1] = 0;
-               result[2] = 0;
-               result[3] = 0;
+               GLfloat a[4], aNext[4], result[4];
+               struct fp_machine dMachine;
+               if (!fetch_vector4_deriv(&inst->SrcReg[0], span, 'Y', result)) {
+                  init_machine_deriv(ctx, machine, program, span,
+                                     'Y', &dMachine);
+                  execute_program(ctx, program, pc, &dMachine, span);
+                  fetch_vector4( &inst->SrcReg[0], &dMachine, aNext );
+                  result[0] = aNext[0] - a[0];
+                  result[1] = aNext[1] - a[1];
+                  result[2] = aNext[2] - a[2];
+                  result[3] = aNext[3] - a[3];
+               }
                store_vector4( inst, machine, result );
             }
             break;
@@ -710,8 +937,7 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
                GLfloat texcoord[4], color[4];
                fetch_vector4( &inst->SrcReg[0], machine, texcoord );
                /* XXX: Undo perspective divide from interpolate_texcoords() */
-               fetch_texel( ctx, texcoord, inst->TexSrcUnit,
-                            inst->TexSrcBit, color );
+               fetch_texel( ctx, texcoord, inst->TexSrcUnit, color );
                store_vector4( inst, machine, color );
             }
             break;
@@ -723,7 +949,7 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
                fetch_vector4( &inst->SrcReg[1], machine, dtdx );
                fetch_vector4( &inst->SrcReg[2], machine, dtdy );
                fetch_texel_deriv( ctx, texcoord, dtdx, dtdy, inst->TexSrcUnit,
-                                  inst->TexSrcBit, color );
+                                  color );
                store_vector4( inst, machine, color );
             }
             break;
@@ -733,8 +959,7 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
                GLfloat texcoord[4], color[4];
                fetch_vector4( &inst->SrcReg[0], machine, texcoord );
                /* Already did perspective divide in interpolate_texcoords() */
-               fetch_texel( ctx, texcoord, inst->TexSrcUnit,
-                            inst->TexSrcBit, color );
+               fetch_texel( ctx, texcoord, inst->TexSrcUnit, color );
                store_vector4( inst, machine, color );
             }
             break;
@@ -801,8 +1026,11 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
                store_vector4( inst, machine, result );
             }
             break;
+         case FP_OPCODE_END:
+            return GL_TRUE;
          default:
-            _mesa_problem(ctx, "Bad opcode in _mesa_exec_fragment_program");
+            _mesa_problem(ctx, "Bad opcode %d in _mesa_exec_fragment_program",
+                          inst->Opcode);
             return GL_TRUE; /* return value doesn't matter */
       }
    }
@@ -810,6 +1038,59 @@ execute_program(GLcontext *ctx, const struct fragment_program *program)
 }
 
 
+static void
+init_machine( GLcontext *ctx, struct fp_machine *machine,
+              const struct fragment_program *program,
+              const struct sw_span *span, GLuint i )
+{
+   GLuint u;
+
+   /* Clear temporary registers */
+   _mesa_bzero(machine->Registers + FP_TEMP_REG_START,
+               MAX_NV_FRAGMENT_PROGRAM_TEMPS * 4 * sizeof(GLfloat));
+
+   /* Load input registers */
+   if (program->InputsRead & (1 << FRAG_ATTRIB_WPOS)) {
+      GLfloat *wpos = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_WPOS];
+      wpos[0] = span->x + i;
+      wpos[1] = span->y + i;
+      wpos[2] = (GLfloat) span->array->z[i] / ctx->DepthMaxF;
+      wpos[3] = span->w + i * span->dwdx;
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_COL0)) {
+      GLfloat *col0 = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_COL0];
+      col0[0] = CHAN_TO_FLOAT(span->array->rgba[i][RCOMP]);
+      col0[1] = CHAN_TO_FLOAT(span->array->rgba[i][GCOMP]);
+      col0[2] = CHAN_TO_FLOAT(span->array->rgba[i][BCOMP]);
+      col0[3] = CHAN_TO_FLOAT(span->array->rgba[i][ACOMP]);
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_COL1)) {
+      GLfloat *col1 = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_COL1];
+      col1[0] = CHAN_TO_FLOAT(span->array->spec[i][RCOMP]);
+      col1[1] = CHAN_TO_FLOAT(span->array->spec[i][GCOMP]);
+      col1[2] = CHAN_TO_FLOAT(span->array->spec[i][BCOMP]);
+      col1[3] = CHAN_TO_FLOAT(span->array->spec[i][ACOMP]);
+   }
+   if (program->InputsRead & (1 << FRAG_ATTRIB_FOGC)) {
+      GLfloat *fogc = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_FOGC];
+      fogc[0] = span->array->fog[i];
+      fogc[1] = 0.0F;
+      fogc[2] = 0.0F;
+      fogc[3] = 0.0F;
+   }
+   for (u = 0; u < ctx->Const.MaxTextureCoordUnits; u++) {
+      if (program->InputsRead & (1 << (FRAG_ATTRIB_TEX0 + u))) {
+         GLfloat *tex = machine->Registers[FP_INPUT_REG_START+FRAG_ATTRIB_TEX0+u];
+         if (ctx->Texture.Unit[u]._ReallyEnabled) {
+            COPY_4V(tex, span->array->texcoords[u][i]);
+         }
+         else {
+            COPY_4V(tex, ctx->Current.Attrib[VERT_ATTRIB_TEX0 + u]);
+         }
+      }
+   }
+}
+
 
 void
 _swrast_exec_nv_fragment_program( GLcontext *ctx, struct sw_span *span )
@@ -819,65 +1100,22 @@ _swrast_exec_nv_fragment_program( GLcontext *ctx, struct sw_span *span )
 
    for (i = 0; i < span->end; i++) {
       if (span->array->mask[i]) {
-         const GLfloat *colOut = ctx->FragmentProgram.Machine.Registers[FP_OUTPUT_REG_START];
-         GLuint u;
-
-         /* Clear temporary registers */
-         _mesa_bzero(ctx->FragmentProgram.Machine.Registers +FP_TEMP_REG_START,
-                     MAX_NV_FRAGMENT_PROGRAM_TEMPS * 4 * sizeof(GLfloat));
-
-         /*
-          * Load input registers - yes this is all very inefficient for now.
-          */
-         if (program->InputsRead & (1 << FRAG_ATTRIB_WPOS)) {
-            GLfloat *wpos = ctx->FragmentProgram.Machine.Registers[0];
-            wpos[0] = span->x + i;
-            wpos[1] = span->y + i;
-            wpos[2] = (GLfloat) span->array->z[i] / ctx->DepthMaxF;
-            wpos[3] = 1.0; /* XXX should be 1/w */
-         }
-         if (program->InputsRead & (1 << FRAG_ATTRIB_COL0)) {
-            GLfloat *col0 = ctx->FragmentProgram.Machine.Registers[1];
-            col0[0] = CHAN_TO_FLOAT(span->array->rgba[i][RCOMP]);
-            col0[1] = CHAN_TO_FLOAT(span->array->rgba[i][GCOMP]);
-            col0[2] = CHAN_TO_FLOAT(span->array->rgba[i][BCOMP]);
-            col0[3] = CHAN_TO_FLOAT(span->array->rgba[i][ACOMP]);
-         }
-         if (program->InputsRead & (1 << FRAG_ATTRIB_COL1)) {
-            GLfloat *col1 = ctx->FragmentProgram.Machine.Registers[2];
-            col1[0] = CHAN_TO_FLOAT(span->array->spec[i][RCOMP]);
-            col1[1] = CHAN_TO_FLOAT(span->array->spec[i][GCOMP]);
-            col1[2] = CHAN_TO_FLOAT(span->array->spec[i][BCOMP]);
-            col1[3] = CHAN_TO_FLOAT(span->array->spec[i][ACOMP]);
-         }
-         if (program->InputsRead & (1 << FRAG_ATTRIB_FOGC)) {
-            GLfloat *fogc = ctx->FragmentProgram.Machine.Registers[3];
-            fogc[0] = span->array->fog[i];
-            fogc[1] = 0.0F;
-            fogc[2] = 0.0F;
-            fogc[3] = 0.0F;
-         }
-         for (u = 0; u < ctx->Const.MaxTextureCoordUnits; u++) {
-            if (program->InputsRead & (1 << (FRAG_ATTRIB_TEX0 + u))) {
-               if (ctx->Texture.Unit[u]._ReallyEnabled) {
-                  COPY_4V(ctx->FragmentProgram.Machine.Registers[4 + u],
-                          span->array->texcoords[u][i]);
-               }
-               else {
-                  COPY_4V(ctx->FragmentProgram.Machine.Registers[4 + u],
-                          ctx->Current.Attrib[VERT_ATTRIB_TEX0 + u]);
-               }
-            }
-         }
+         init_machine(ctx, &ctx->FragmentProgram.Machine,
+                      ctx->FragmentProgram.Current, span, i);
 
-         if (!execute_program(ctx, program))
+         if (!execute_program(ctx, program, ~0,
+                              &ctx->FragmentProgram.Machine, span))
             span->array->mask[i] = GL_FALSE;  /* killed fragment */
 
          /* Store output registers */
-         UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][RCOMP], colOut[0]);
-         UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][GCOMP], colOut[1]);
-         UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][BCOMP], colOut[2]);
-         UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][ACOMP], colOut[3]);
+         {
+            const GLfloat *colOut
+               = ctx->FragmentProgram.Machine.Registers[FP_OUTPUT_REG_START];
+            UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][RCOMP], colOut[0]);
+            UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][GCOMP], colOut[1]);
+            UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][BCOMP], colOut[2]);
+            UNCLAMPED_FLOAT_TO_CHAN(span->array->rgba[i][ACOMP], colOut[3]);
+         }
          /* depth value */
          if (ctx->FragmentProgram.Current->OutputsWritten & 2)
             span->array->z[i] = IROUND(ctx->FragmentProgram.Machine.Registers[FP_OUTPUT_REG_START + 2][0] * ctx->DepthMaxF);
diff --git a/src/mesa/swrast/s_span.c b/src/mesa/swrast/s_span.c
index cb02ab924d..842f3be3c2 100644
--- a/src/mesa/swrast/s_span.c
+++ b/src/mesa/swrast/s_span.c
@@ -1,4 +1,4 @@
-/* $Id: s_span.c,v 1.58 2003/03/15 17:33:27 brianp Exp $ */
+/* $Id: s_span.c,v 1.59 2003/03/16 22:02:37 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -76,7 +76,7 @@ void
 _mesa_span_default_fog( GLcontext *ctx, struct sw_span *span )
 {
    span->fog = _mesa_z_to_fogfactor(ctx, ctx->Current.RasterDistance);
-   span->fogStep = 0;
+   span->fogStep = span->dfogdx = span->dfogdy = 0.0F;
    span->interpMask |= SPAN_FOG;
 }
 
diff --git a/src/mesa/swrast/s_triangle.c b/src/mesa/swrast/s_triangle.c
index 538102f41f..fce782466f 100644
--- a/src/mesa/swrast/s_triangle.c
+++ b/src/mesa/swrast/s_triangle.c
@@ -1,4 +1,4 @@
-/* $Id: s_triangle.c,v 1.68 2003/03/14 15:41:00 brianp Exp $ */
+/* $Id: s_triangle.c,v 1.69 2003/03/16 22:02:38 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -870,6 +870,7 @@ fast_persp_span(GLcontext *ctx, struct sw_span *span,
  */
 #define NAME general_textured_triangle
 #define INTERP_Z 1
+#define INTERP_W 1
 #define INTERP_FOG 1
 #define DEPTH_TYPE DEFAULT_SOFTWARE_DEPTH_TYPE
 #define INTERP_RGB 1
@@ -888,6 +889,7 @@ fast_persp_span(GLcontext *ctx, struct sw_span *span,
  */
 #define NAME multitextured_triangle
 #define INTERP_Z 1
+#define INTERP_W 1
 #define INTERP_FOG 1
 #define DEPTH_TYPE DEFAULT_SOFTWARE_DEPTH_TYPE
 #define INTERP_RGB 1
diff --git a/src/mesa/swrast/s_tritemp.h b/src/mesa/swrast/s_tritemp.h
index 37d17d4bc8..b5273500ce 100644
--- a/src/mesa/swrast/s_tritemp.h
+++ b/src/mesa/swrast/s_tritemp.h
@@ -1,4 +1,4 @@
-/* $Id: s_tritemp.h,v 1.46 2003/03/16 20:10:01 brianp Exp $ */
+/* $Id: s_tritemp.h,v 1.47 2003/03/16 22:02:40 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -301,25 +301,6 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 
    {
       GLint scan_from_left_to_right;  /* true if scanning left-to-right */
-#ifdef INTERP_Z
-      GLfloat dzdx, dzdy;
-#endif
-#ifdef INTERP_FOG
-      GLfloat dfogdy;
-#endif
-#if defined(INTERP_RGB)
-      GLfloat drdx, drdy;
-      GLfloat dgdx, dgdy;
-      GLfloat dbdx, dbdy;
-#endif
-#if defined(INTERP_ALPHA)
-      GLfloat dadx, dady;
-#endif
-#if defined(INTERP_SPEC)
-      GLfloat dsrdx, dsrdy;
-      GLfloat dsgdx, dsgdy;
-      GLfloat dsbdx, dsbdy;
-#endif
 #ifdef INTERP_INDEX
       GLfloat didx, didy;
 #endif
@@ -338,22 +319,29 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #ifdef INTERP_Z
       span.interpMask |= SPAN_Z;
       {
-         GLfloat eMaj_dz, eBot_dz;
-         eMaj_dz = vMax->win[2] - vMin->win[2];
-         eBot_dz = vMid->win[2] - vMin->win[2];
-         dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
-         if (dzdx > maxDepth || dzdx < -maxDepth) {
+         GLfloat eMaj_dz = vMax->win[2] - vMin->win[2];
+         GLfloat eBot_dz = vMid->win[2] - vMin->win[2];
+         span.dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
+         if (span.dzdx > maxDepth || span.dzdx < -maxDepth) {
             /* probably a sliver triangle */
-            dzdx = 0.0;
-            dzdy = 0.0;
+            span.dzdx = 0.0;
+            span.dzdy = 0.0;
          }
          else {
-            dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
+            span.dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
          }
          if (depthBits <= 16)
-            span.zStep = SignedFloatToFixed(dzdx);
+            span.zStep = SignedFloatToFixed(span.dzdx);
          else
-            span.zStep = (GLint) dzdx;
+            span.zStep = (GLint) span.dzdx;
+      }
+#endif
+#ifdef INTERP_W
+      {
+         const GLfloat eMaj_dw = vMax->win[3] - vMin->win[3];
+         const GLfloat eBot_dw = vMid->win[3] - vMin->win[3];
+         span.dwdx = oneOverArea * (eMaj_dw * eBot.dy - eMaj.dy * eBot_dw);
+         span.dwdy = oneOverArea * (eMaj.dx * eBot_dw - eMaj_dw * eBot.dx);
       }
 #endif
 #ifdef INTERP_FOG
@@ -361,8 +349,9 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
       {
          const GLfloat eMaj_dfog = vMax->fog - vMin->fog;
          const GLfloat eBot_dfog = vMid->fog - vMin->fog;
-         span.fogStep = oneOverArea * (eMaj_dfog * eBot.dy - eMaj.dy * eBot_dfog);
-         dfogdy = oneOverArea * (eMaj.dx * eBot_dfog - eMaj_dfog * eBot.dx);
+         span.dfogdx = oneOverArea * (eMaj_dfog * eBot.dy - eMaj.dy * eBot_dfog);
+         span.dfogdy = oneOverArea * (eMaj.dx * eBot_dfog - eMaj_dfog * eBot.dx);
+         span.fogStep = span.dfogdx;
       }
 #endif
 #ifdef INTERP_RGB
@@ -378,39 +367,39 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
          GLfloat eMaj_da = (GLfloat) ((ColorTemp) vMax->color[ACOMP] - vMin->color[ACOMP]);
          GLfloat eBot_da = (GLfloat) ((ColorTemp) vMid->color[ACOMP] - vMin->color[ACOMP]);
 #  endif
-         drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
-         drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
-         dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
-         dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
-         dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
-         dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
+         span.drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
+         span.drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
+         span.dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
+         span.dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
+         span.dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
+         span.dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
 #  if CHAN_TYPE == GL_FLOAT
-         span.redStep   = drdx;
-         span.greenStep = dgdx;
-         span.blueStep  = dbdx;
+         span.redStep   = span.drdx;
+         span.greenStep = span.dgdx;
+         span.blueStep  = span.dbdx;
 #  else
-         span.redStep   = SignedFloatToFixed(drdx);
-         span.greenStep = SignedFloatToFixed(dgdx);
-         span.blueStep  = SignedFloatToFixed(dbdx);
+         span.redStep   = SignedFloatToFixed(span.drdx);
+         span.greenStep = SignedFloatToFixed(span.dgdx);
+         span.blueStep  = SignedFloatToFixed(span.dbdx);
 #  endif /* GL_FLOAT */
 #  ifdef INTERP_ALPHA
-         dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
-         dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
+         span.dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
+         span.dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
 #    if CHAN_TYPE == GL_FLOAT
-         span.alphaStep = dadx;
+         span.alphaStep = span.dadx;
 #    else
-         span.alphaStep = SignedFloatToFixed(dadx);
+         span.alphaStep = SignedFloatToFixed(span.dadx);
 #    endif /* GL_FLOAT */
 #  endif /* INTERP_ALPHA */
       }
       else {
          ASSERT (ctx->Light.ShadeModel == GL_FLAT);
          span.interpMask |= SPAN_FLAT;
-         drdx = drdy = span.redStep   = 0;
-         dgdx = dgdy = span.greenStep = 0;
-         dbdx = dbdy = span.blueStep  = 0;
+         span.drdx = span.drdy = span.redStep   = 0;
+         span.dgdx = span.dgdy = span.greenStep = 0;
+         span.dbdx = span.dbdy = span.blueStep  = 0;
 #  ifdef INTERP_ALPHA
-         dadx = dady = span.alphaStep = 0;
+         span.dadx = span.dady = span.alphaStep = 0;
 #  endif
       }
 #endif /* INTERP_RGB */
@@ -423,26 +412,26 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
          GLfloat eBot_dsg = (GLfloat) ((ColorTemp) vMid->specular[GCOMP] - vMin->specular[GCOMP]);
          GLfloat eMaj_dsb = (GLfloat) ((ColorTemp) vMax->specular[BCOMP] - vMin->specular[BCOMP]);
          GLfloat eBot_dsb = (GLfloat) ((ColorTemp) vMid->specular[BCOMP] - vMin->specular[BCOMP]);
-         dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr);
-         dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx);
-         dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg);
-         dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx);
-         dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb);
-         dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx);
+         span.dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr);
+         span.dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx);
+         span.dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg);
+         span.dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx);
+         span.dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb);
+         span.dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx);
 #  if CHAN_TYPE == GL_FLOAT
-         span.specRedStep   = dsrdx;
-         span.specGreenStep = dsgdx;
-         span.specBlueStep  = dsbdx;
+         span.specRedStep   = span.dsrdx;
+         span.specGreenStep = span.dsgdx;
+         span.specBlueStep  = span.dsbdx;
 #  else
-         span.specRedStep   = SignedFloatToFixed(dsrdx);
-         span.specGreenStep = SignedFloatToFixed(dsgdx);
-         span.specBlueStep  = SignedFloatToFixed(dsbdx);
+         span.specRedStep   = SignedFloatToFixed(span.dsrdx);
+         span.specGreenStep = SignedFloatToFixed(span.dsgdx);
+         span.specBlueStep  = SignedFloatToFixed(span.dsbdx);
 #  endif
       }
       else {
-         dsrdx = dsrdy = span.specRedStep   = 0;
-         dsgdx = dsgdy = span.specGreenStep = 0;
-         dsbdx = dsbdy = span.specBlueStep  = 0;
+         span.dsrdx = span.dsrdy = span.specRedStep   = 0;
+         span.dsgdx = span.dsgdy = span.specGreenStep = 0;
+         span.dsbdx = span.dsbdy = span.specBlueStep  = 0;
       }
 #endif /* INTERP_SPEC */
 #ifdef INTERP_INDEX
@@ -568,30 +557,33 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
          DEPTH_TYPE *zRow = NULL;
          int dZRowOuter = 0, dZRowInner;  /* offset in bytes */
 #  endif
-         GLfixed fz = 0, fdzOuter = 0, fdzInner;
+         GLfixed zLeft = 0, fdzOuter = 0, fdzInner;
+#endif
+#ifdef INTERP_W
+         GLfloat wLeft, dwOuter, dwInner;
 #endif
 #ifdef INTERP_FOG
          GLfloat fogLeft = 0, dfogOuter = 0, dfogInner;
 #endif
 #ifdef INTERP_RGB
-         ColorTemp fr = 0, fdrOuter = 0, fdrInner;
-         ColorTemp fg = 0, fdgOuter = 0, fdgInner;
-         ColorTemp fb = 0, fdbOuter = 0, fdbInner;
+         ColorTemp rLeft = 0, fdrOuter = 0, fdrInner;
+         ColorTemp gLeft = 0, fdgOuter = 0, fdgInner;
+         ColorTemp bLeft = 0, fdbOuter = 0, fdbInner;
 #endif
 #ifdef INTERP_ALPHA
-         ColorTemp fa = 0, fdaOuter = 0, fdaInner;
+         ColorTemp aLeft = 0, fdaOuter = 0, fdaInner;
 #endif
 #ifdef INTERP_SPEC
-         ColorTemp fsr=0, fdsrOuter=0, fdsrInner;
-         ColorTemp fsg=0, fdsgOuter=0, fdsgInner;
-         ColorTemp fsb=0, fdsbOuter=0, fdsbInner;
+         ColorTemp srLeft=0, dsrOuter=0, dsrInner;
+         ColorTemp sgLeft=0, dsgOuter=0, dsgInner;
+         ColorTemp sbLeft=0, dsbOuter=0, dsbInner;
 #endif
 #ifdef INTERP_INDEX
-         GLfixed fi=0, fdiOuter=0, fdiInner;
+         GLfixed iLeft=0, diOuter=0, diInner;
 #endif
 #ifdef INTERP_INT_TEX
-         GLfixed fs=0, fdsOuter=0, fdsInner;
-         GLfixed ft=0, fdtOuter=0, fdtInner;
+         GLfixed sLeft=0, dsOuter=0, dsInner;
+         GLfixed tLeft=0, dtOuter=0, dtInner;
 #endif
 #ifdef INTERP_TEX
          GLfloat sLeft[MAX_TEXTURE_COORD_UNITS];
@@ -695,17 +687,17 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                   GLfloat z0 = vLower->win[2];
                   if (depthBits <= 16) {
                      /* interpolate fixed-pt values */
-                     GLfloat tmp = (z0 * FIXED_SCALE + dzdx * adjx + dzdy * adjy) + FIXED_HALF;
+                     GLfloat tmp = (z0 * FIXED_SCALE + span.dzdx * adjx + span.dzdy * adjy) + FIXED_HALF;
                      if (tmp < MAX_GLUINT / 2)
-                        fz = (GLfixed) tmp;
+                        zLeft = (GLfixed) tmp;
                      else
-                        fz = MAX_GLUINT / 2;
-                     fdzOuter = SignedFloatToFixed(dzdy + dxOuter * dzdx);
+                        zLeft = MAX_GLUINT / 2;
+                     fdzOuter = SignedFloatToFixed(span.dzdy + dxOuter * span.dzdx);
                   }
                   else {
                      /* interpolate depth values exactly */
-                     fz = (GLint) (z0 + dzdx * FixedToFloat(adjx) + dzdy * FixedToFloat(adjy));
-                     fdzOuter = (GLint) (dzdy + dxOuter * dzdx);
+                     zLeft = (GLint) (z0 + span.dzdx * FixedToFloat(adjx) + span.dzdy * FixedToFloat(adjy));
+                     fdzOuter = (GLint) (span.dzdy + dxOuter * span.dzdx);
                   }
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *)
@@ -714,57 +706,60 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  endif
                }
 #endif
+#ifdef INTERP_W
+               wLeft = vLower->win[3] + (span.dwdx * adjx + span.dwdy * adjy) * (1.0F/FIXED_SCALE);
+               dwOuter = span.dwdy + dxOuter * span.dwdx;
+#endif
 #ifdef INTERP_FOG
-               fogLeft = vLower->fog + (span.fogStep * adjx + dfogdy * adjy)
-                                       * (1.0F/FIXED_SCALE);
-               dfogOuter = dfogdy + dxOuter * span.fogStep;
+               fogLeft = vLower->fog + (span.dfogdx * adjx + span.dfogdy * adjy) * (1.0F/FIXED_SCALE);
+               dfogOuter = span.dfogdy + dxOuter * span.dfogdx;
 #endif
 #ifdef INTERP_RGB
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
 #  if CHAN_TYPE == GL_FLOAT
-                  fr = vLower->color[RCOMP] + (drdx * adjx + drdy * adjy) * (1.0F / FIXED_SCALE);
-                  fg = vLower->color[GCOMP] + (dgdx * adjx + dgdy * adjy) * (1.0F / FIXED_SCALE);
-                  fb = vLower->color[BCOMP] + (dbdx * adjx + dbdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdrOuter = drdy + dxOuter * drdx;
-                  fdgOuter = dgdy + dxOuter * dgdx;
-                  fdbOuter = dbdy + dxOuter * dbdx;
+                  rLeft = vLower->color[RCOMP] + (span.drdx * adjx + span.drdy * adjy) * (1.0F / FIXED_SCALE);
+                  gLeft = vLower->color[GCOMP] + (span.dgdx * adjx + span.dgdy * adjy) * (1.0F / FIXED_SCALE);
+                  bLeft = vLower->color[BCOMP] + (span.dbdx * adjx + span.dbdy * adjy) * (1.0F / FIXED_SCALE);
+                  fdrOuter = span.drdy + dxOuter * span.drdx;
+                  fdgOuter = span.dgdy + dxOuter * span.dgdx;
+                  fdbOuter = span.dbdy + dxOuter * span.dbdx;
 #  else
-                  fr = (ChanToFixed(vLower->color[RCOMP]) + drdx * adjx + drdy * adjy) + FIXED_HALF;
-                  fg = (ChanToFixed(vLower->color[GCOMP]) + dgdx * adjx + dgdy * adjy) + FIXED_HALF;
-                  fb = (ChanToFixed(vLower->color[BCOMP]) + dbdx * adjx + dbdy * adjy) + FIXED_HALF;
-                  fdrOuter = SignedFloatToFixed(drdy + dxOuter * drdx);
-                  fdgOuter = SignedFloatToFixed(dgdy + dxOuter * dgdx);
-                  fdbOuter = SignedFloatToFixed(dbdy + dxOuter * dbdx);
+                  rLeft = (ChanToFixed(vLower->color[RCOMP]) + span.drdx * adjx + span.drdy * adjy) + FIXED_HALF;
+                  gLeft = (ChanToFixed(vLower->color[GCOMP]) + span.dgdx * adjx + span.dgdy * adjy) + FIXED_HALF;
+                  bLeft = (ChanToFixed(vLower->color[BCOMP]) + span.dbdx * adjx + span.dbdy * adjy) + FIXED_HALF;
+                  fdrOuter = SignedFloatToFixed(span.drdy + dxOuter * span.drdx);
+                  fdgOuter = SignedFloatToFixed(span.dgdy + dxOuter * span.dgdx);
+                  fdbOuter = SignedFloatToFixed(span.dbdy + dxOuter * span.dbdx);
 #  endif
 #  ifdef INTERP_ALPHA
 #    if CHAN_TYPE == GL_FLOAT
-                  fa = vLower->color[ACOMP] + (dadx * adjx + dady * adjy) * (1.0F / FIXED_SCALE);
-                  fdaOuter = dady + dxOuter * dadx;
+                  aLeft = vLower->color[ACOMP] + (span.dadx * adjx + span.dady * adjy) * (1.0F / FIXED_SCALE);
+                  fdaOuter = span.dady + dxOuter * span.dadx;
 #    else
-                  fa = (ChanToFixed(vLower->color[ACOMP]) + dadx * adjx + dady * adjy) + FIXED_HALF;
-                  fdaOuter = SignedFloatToFixed(dady + dxOuter * dadx);
+                  aLeft = (ChanToFixed(vLower->color[ACOMP]) + span.dadx * adjx + span.dady * adjy) + FIXED_HALF;
+                  fdaOuter = SignedFloatToFixed(span.dady + dxOuter * span.dadx);
 #    endif
 #  endif
                }
                else {
                   ASSERT (ctx->Light.ShadeModel == GL_FLAT);
 #  if CHAN_TYPE == GL_FLOAT
-                  fr = v2->color[RCOMP];
-                  fg = v2->color[GCOMP];
-                  fb = v2->color[BCOMP];
+                  rLeft = v2->color[RCOMP];
+                  gLeft = v2->color[GCOMP];
+                  bLeft = v2->color[BCOMP];
                   fdrOuter = fdgOuter = fdbOuter = 0.0F;
 #  else
-                  fr = ChanToFixed(v2->color[RCOMP]);
-                  fg = ChanToFixed(v2->color[GCOMP]);
-                  fb = ChanToFixed(v2->color[BCOMP]);
+                  rLeft = ChanToFixed(v2->color[RCOMP]);
+                  gLeft = ChanToFixed(v2->color[GCOMP]);
+                  bLeft = ChanToFixed(v2->color[BCOMP]);
                   fdrOuter = fdgOuter = fdbOuter = 0;
 #  endif
 #  ifdef INTERP_ALPHA
 #    if CHAN_TYPE == GL_FLOAT
-                  fa = v2->color[ACOMP];
+                  aLeft = v2->color[ACOMP];
                   fdaOuter = 0.0F;
 #    else
-                  fa = ChanToFixed(v2->color[ACOMP]);
+                  aLeft = ChanToFixed(v2->color[ACOMP]);
                   fdaOuter = 0;
 #    endif
 #  endif
@@ -774,59 +769,59 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #ifdef INTERP_SPEC
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
 #  if CHAN_TYPE == GL_FLOAT
-                  fsr = vLower->specular[RCOMP] + (dsrdx * adjx + dsrdy * adjy) * (1.0F / FIXED_SCALE);
-                  fsg = vLower->specular[GCOMP] + (dsgdx * adjx + dsgdy * adjy) * (1.0F / FIXED_SCALE);
-                  fsb = vLower->specular[BCOMP] + (dsbdx * adjx + dsbdy * adjy) * (1.0F / FIXED_SCALE);
-                  fdsrOuter = dsrdy + dxOuter * dsrdx;
-                  fdsgOuter = dsgdy + dxOuter * dsgdx;
-                  fdsbOuter = dsbdy + dxOuter * dsbdx;
+                  srLeft = vLower->specular[RCOMP] + (span.dsrdx * adjx + span.dsrdy * adjy) * (1.0F / FIXED_SCALE);
+                  sgLeft = vLower->specular[GCOMP] + (span.dsgdx * adjx + span.dsgdy * adjy) * (1.0F / FIXED_SCALE);
+                  sbLeft = vLower->specular[BCOMP] + (span.dsbdx * adjx + span.dsbdy * adjy) * (1.0F / FIXED_SCALE);
+                  dsrOuter = span.dsrdy + dxOuter * span.dsrdx;
+                  dsgOuter = span.dsgdy + dxOuter * span.dsgdx;
+                  dsbOuter = span.dsbdy + dxOuter * span.dsbdx;
 #  else
-                  fsr = (GLfixed) (ChanToFixed(vLower->specular[RCOMP]) + dsrdx * adjx + dsrdy * adjy) + FIXED_HALF;
-                  fsg = (GLfixed) (ChanToFixed(vLower->specular[GCOMP]) + dsgdx * adjx + dsgdy * adjy) + FIXED_HALF;
-                  fsb = (GLfixed) (ChanToFixed(vLower->specular[BCOMP]) + dsbdx * adjx + dsbdy * adjy) + FIXED_HALF;
-                  fdsrOuter = SignedFloatToFixed(dsrdy + dxOuter * dsrdx);
-                  fdsgOuter = SignedFloatToFixed(dsgdy + dxOuter * dsgdx);
-                  fdsbOuter = SignedFloatToFixed(dsbdy + dxOuter * dsbdx);
+                  srLeft = (GLfixed) (ChanToFixed(vLower->specular[RCOMP]) + span.dsrdx * adjx + span.dsrdy * adjy) + FIXED_HALF;
+                  sgLeft = (GLfixed) (ChanToFixed(vLower->specular[GCOMP]) + span.dsgdx * adjx + span.dsgdy * adjy) + FIXED_HALF;
+                  sbLeft = (GLfixed) (ChanToFixed(vLower->specular[BCOMP]) + span.dsbdx * adjx + span.dsbdy * adjy) + FIXED_HALF;
+                  dsrOuter = SignedFloatToFixed(span.dsrdy + dxOuter * span.dsrdx);
+                  dsgOuter = SignedFloatToFixed(span.dsgdy + dxOuter * span.dsgdx);
+                  dsbOuter = SignedFloatToFixed(span.dsbdy + dxOuter * span.dsbdx);
 #  endif
                }
                else {
 #if  CHAN_TYPE == GL_FLOAT
-                  fsr = v2->specular[RCOMP];
-                  fsg = v2->specular[GCOMP];
-                  fsb = v2->specular[BCOMP];
-                  fdsrOuter = fdsgOuter = fdsbOuter = 0.0F;
+                  srLeft = v2->specular[RCOMP];
+                  sgLeft = v2->specular[GCOMP];
+                  sbLeft = v2->specular[BCOMP];
+                  dsrOuter = dsgOuter = dsbOuter = 0.0F;
 #  else
-                  fsr = ChanToFixed(v2->specular[RCOMP]);
-                  fsg = ChanToFixed(v2->specular[GCOMP]);
-                  fsb = ChanToFixed(v2->specular[BCOMP]);
-                  fdsrOuter = fdsgOuter = fdsbOuter = 0;
+                  srLeft = ChanToFixed(v2->specular[RCOMP]);
+                  sgLeft = ChanToFixed(v2->specular[GCOMP]);
+                  sbLeft = ChanToFixed(v2->specular[BCOMP]);
+                  dsrOuter = dsgOuter = dsbOuter = 0;
 #  endif
                }
 #endif
 
 #ifdef INTERP_INDEX
                if (ctx->Light.ShadeModel == GL_SMOOTH) {
-                  fi = (GLfixed)(vLower->index * FIXED_SCALE
+                  iLeft = (GLfixed)(vLower->index * FIXED_SCALE
                                  + didx * adjx + didy * adjy) + FIXED_HALF;
-                  fdiOuter = SignedFloatToFixed(didy + dxOuter * didx);
+                  diOuter = SignedFloatToFixed(didy + dxOuter * didx);
                }
                else {
-                  fi = (GLfixed) (v2->index * FIXED_SCALE);
-                  fdiOuter = 0;
+                  iLeft = (GLfixed) (v2->index * FIXED_SCALE);
+                  diOuter = 0;
                }
 #endif
 #ifdef INTERP_INT_TEX
                {
                   GLfloat s0, t0;
                   s0 = vLower->texcoord[0][0] * S_SCALE;
-                  fs = (GLfixed)(s0 * FIXED_SCALE + span.texStepX[0][0] * adjx
+                  sLeft = (GLfixed)(s0 * FIXED_SCALE + span.texStepX[0][0] * adjx
                                  + span.texStepY[0][0] * adjy) + FIXED_HALF;
-                  fdsOuter = SignedFloatToFixed(span.texStepY[0][0] + dxOuter * span.texStepX[0][0]);
+                  dsOuter = SignedFloatToFixed(span.texStepY[0][0] + dxOuter * span.texStepX[0][0]);
 
                   t0 = vLower->texcoord[0][1] * T_SCALE;
-                  ft = (GLfixed)(t0 * FIXED_SCALE + span.texStepX[0][1] * adjx
+                  tLeft = (GLfixed)(t0 * FIXED_SCALE + span.texStepX[0][1] * adjx
                                  + span.texStepY[0][1] * adjy) + FIXED_HALF;
-                  fdtOuter = SignedFloatToFixed(span.texStepY[0][1] + dxOuter * span.texStepX[0][1]);
+                  dtOuter = SignedFloatToFixed(span.texStepY[0][1] + dxOuter * span.texStepX[0][1]);
                }
 #endif
 #ifdef INTERP_TEX
@@ -869,8 +864,11 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  endif
             fdzInner = fdzOuter + span.zStep;
 #endif
+#ifdef INTERP_W
+            dwInner = dwOuter + span.dwdx;
+#endif
 #ifdef INTERP_FOG
-            dfogInner = dfogOuter + span.fogStep;
+            dfogInner = dfogOuter + span.dfogdx;
 #endif
 #if defined(INTERP_RGB)
             fdrInner = fdrOuter + span.redStep;
@@ -881,16 +879,16 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
             fdaInner = fdaOuter + span.alphaStep;
 #endif
 #if defined(INTERP_SPEC)
-            fdsrInner = fdsrOuter + span.specRedStep;
-            fdsgInner = fdsgOuter + span.specGreenStep;
-            fdsbInner = fdsbOuter + span.specBlueStep;
+            dsrInner = dsrOuter + span.specRedStep;
+            dsgInner = dsgOuter + span.specGreenStep;
+            dsbInner = dsbOuter + span.specBlueStep;
 #endif
 #ifdef INTERP_INDEX
-            fdiInner = fdiOuter + span.indexStep;
+            diInner = diOuter + span.indexStep;
 #endif
 #ifdef INTERP_INT_TEX
-            fdsInner = fdsOuter + span.intTexStep[0];
-            fdtInner = fdtOuter + span.intTexStep[1];
+            dsInner = dsOuter + span.intTexStep[0];
+            dtInner = dtOuter + span.intTexStep[1];
 #endif
 #ifdef INTERP_TEX
             TEX_UNIT_LOOP(
@@ -914,30 +912,33 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
                   span.end = right - span.x;
 
 #ifdef INTERP_Z
-               span.z = fz;
+               span.z = zLeft;
+#endif
+#ifdef INTERP_W
+               span.w = wLeft;
 #endif
 #ifdef INTERP_FOG
                span.fog = fogLeft;
 #endif
 #if defined(INTERP_RGB)
-               span.red = fr;
-               span.green = fg;
-               span.blue = fb;
+               span.red = rLeft;
+               span.green = gLeft;
+               span.blue = bLeft;
 #endif
 #if defined(INTERP_ALPHA)
-               span.alpha = fa;
+               span.alpha = aLeft;
 #endif
 #if defined(INTERP_SPEC)
-               span.specRed = fsr;
-               span.specGreen = fsg;
-               span.specBlue = fsb;
+               span.specRed = srLeft;
+               span.specGreen = sgLeft;
+               span.specBlue = sbLeft;
 #endif
 #ifdef INTERP_INDEX
-               span.index = fi;
+               span.index = iLeft;
 #endif
 #ifdef INTERP_INT_TEX
-               span.intTex[0] = fs;
-               span.intTex[1] = ft;
+               span.intTex[0] = sLeft;
+               span.intTex[1] = tLeft;
 #endif
 
 #ifdef INTERP_TEX
@@ -1040,30 +1041,33 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowOuter);
 #  endif
-                  fz += fdzOuter;
+                  zLeft += fdzOuter;
+#endif
+#ifdef INTERP_W
+                  wLeft += dwOuter;
 #endif
 #ifdef INTERP_FOG
                   fogLeft += dfogOuter;
 #endif
 #if defined(INTERP_RGB)
-                  fr += fdrOuter;
-                  fg += fdgOuter;
-                  fb += fdbOuter;
+                  rLeft += fdrOuter;
+                  gLeft += fdgOuter;
+                  bLeft += fdbOuter;
 #endif
 #if defined(INTERP_ALPHA)
-                  fa += fdaOuter;
+                  aLeft += fdaOuter;
 #endif
 #if defined(INTERP_SPEC)
-                  fsr += fdsrOuter;
-                  fsg += fdsgOuter;
-                  fsb += fdsbOuter;
+                  srLeft += dsrOuter;
+                  sgLeft += dsgOuter;
+                  sbLeft += dsbOuter;
 #endif
 #ifdef INTERP_INDEX
-                  fi += fdiOuter;
+                  iLeft += diOuter;
 #endif
 #ifdef INTERP_INT_TEX
-                  fs += fdsOuter;
-                  ft += fdtOuter;
+                  sLeft += dsOuter;
+                  tLeft += dtOuter;
 #endif
 #ifdef INTERP_TEX
                   TEX_UNIT_LOOP(
@@ -1082,30 +1086,33 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #  ifdef DEPTH_TYPE
                   zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowInner);
 #  endif
-                  fz += fdzInner;
+                  zLeft += fdzInner;
+#endif
+#ifdef INTERP_W
+                  wLeft += dwInner;
 #endif
 #ifdef INTERP_FOG
                   fogLeft += dfogInner;
 #endif
 #if defined(INTERP_RGB)
-                  fr += fdrInner;
-                  fg += fdgInner;
-                  fb += fdbInner;
+                  rLeft += fdrInner;
+                  gLeft += fdgInner;
+                  bLeft += fdbInner;
 #endif
 #if defined(INTERP_ALPHA)
-                  fa += fdaInner;
+                  aLeft += fdaInner;
 #endif
 #if defined(INTERP_SPEC)
-                  fsr += fdsrInner;
-                  fsg += fdsgInner;
-                  fsb += fdsbInner;
+                  srLeft += dsrInner;
+                  sgLeft += dsgInner;
+                  sbLeft += dsbInner;
 #endif
 #ifdef INTERP_INDEX
-                  fi += fdiInner;
+                  iLeft += diInner;
 #endif
 #ifdef INTERP_INT_TEX
-                  fs += fdsInner;
-                  ft += fdtInner;
+                  sLeft += dsInner;
+                  tLeft += dtInner;
 #endif
 #ifdef INTERP_TEX
                   TEX_UNIT_LOOP(
@@ -1136,6 +1143,7 @@ static void NAME(GLcontext *ctx, const SWvertex *v0,
 #undef PIXEL_ADDRESS
 
 #undef INTERP_Z
+#undef INTERP_W
 #undef INTERP_FOG
 #undef INTERP_RGB
 #undef INTERP_ALPHA