diff options
Diffstat (limited to 'src/mesa/swrast_setup/NOTES')
| -rw-r--r-- | src/mesa/swrast_setup/NOTES | 79 |
1 files changed, 32 insertions, 47 deletions
diff --git a/src/mesa/swrast_setup/NOTES b/src/mesa/swrast_setup/NOTES index 4445b332d9..c6cb4ab348 100644 --- a/src/mesa/swrast_setup/NOTES +++ b/src/mesa/swrast_setup/NOTES @@ -6,10 +6,8 @@ swrast vertices from the t&l vertex_buffer structs, and to use them to perform triangle setup functions not implemented in the software rasterizer. -The module provides a RasterSetup function to plug into the t&l driver -interface. This hook had previously been used for hardware -rasterizers, with the software rasterizer taking its data directly -from the vertex buffer. +The module implements a full set of functions to plug into the +t_vb_render.c driver interface (tnl->Driver.Render.*). There are strong advantages to decoupling the software rasterizer from the t&l module, primarily allowing hardware drivers better control @@ -18,63 +16,50 @@ rasterizer in the t&l module, allowing the two modules to evolve independently and allowing either to be substituted with equivalent functionality from another codebase. -This module provides helpers for triangle/quad setup for offset, -unfilled and twoside-lit triangles. The software rasterizer doesn't -handle these primitives directly. +This module implements triangle/quad setup for offset, unfilled and +twoside-lit triangles. The software rasterizer doesn't handle these +primitives directly. -Hardware rasterization drivers probably have little use for this -module. Rather, they might provide a layer that translates their -native (hardware) vertices to swrast vertices before calling into the -swrast module for fallbacks. +Hardware rasterization drivers typically use this module in situations +where no hardware rasterization is possible, ie during total +fallbacks. STATE -This module associates an array of SWvertex structs with each VB. -Thus there are: - - GLboolean _swsetup_RegisterVB( struct vertex_buffer *VB ); - void _swsetup_UnregisterVB( struct vertex_buffer *VB ); - -Which must be called to create and destroy internal vertex storage for -this module. - -To create and destroy the module itself: +To create and destroy the module: GLboolean _swsetup_CreateContext( GLcontext *ctx ); void _swsetup_DestroyContext( GLcontext *ctx ); -Like the software rasterizer, this module tracks state changes -internally and maintains a set of entry points which will always -reflect the current state. For this to work, the driver must call: - - void _swsetup_InvalidateState( GLcontext *ctx, GLuint new_state ); +The module is not active by default, and must be installed by calling +_swrast_Wakeup(). This function installs internal swrast_setup +functions into all the tnl->Driver.Render driver hooks, thus taking +over the task of rasterization entirely: -SERVICES + void _swrast_Wakeup( GLcontext *ctx ); -The module provides the following entrypoints: + +This module tracks state changes internally and maintains derived +values based on the current state. For this to work, the driver +ensure the following funciton is called whenever the state changes and +the swsetup module is 'awake': - void _swrast_RasterSetup( struct vertex_buffer *VB, - GLuint start, GLuint end ); - -Build SWvertices for <VB> between indices start and end. - - void _swsetup_Quad( GLcontext *ctx, GLuint v0, GLuint v1, - GLuint v2, GLuint v3, GLuint pv ); - - void _swsetup_Triangle( GLcontext *ctx, GLuint v0, GLuint v1, - GLuint v2, GLuint pv ); + void _swsetup_InvalidateState( GLcontext *ctx, GLuint new_state ); - void _swsetup_Line( GLcontext *ctx, GLuint v0, GLuint v1, GLuint pv ); +There is no explicit call to put the swsetup module to sleep. Simply +install other function pointers into all the tnl->Driver.Render.* +hooks, and (optionally) cease calling _swsetup_InvalidateState(). +DRIVER INTERFACE - void _swsetup_Points( GLcontext *ctx, GLuint first, GLuint last ); +The module offers a minimal driver interface: -Draw quad, triangle, line, points. Note that these are in the format -expected by core mesa. The Quad and Triangle functions handle -unfilled, offset, twoside-lit and flat-shaded primitives correctly. + void (*Start)( GLcontext *ctx ); + void (*Finish)( GLcontext *ctx ); + +These are called before and after the completion of all swrast drawing +activity. As swrast doesn't call callbacks during triangle, line or +point rasterization, these are necessary to provide locking hooks for +some drivers. They may otherwise be left null. -These functions can thus be plugged into the ctx->Driver struct and -left permanently in place, providing the InvalidateState() routine is -correctly called on state changes. -
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