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Diffstat (limited to 'progs/glsl/array.c')
| -rw-r--r-- | progs/glsl/array.c | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/progs/glsl/array.c b/progs/glsl/array.c new file mode 100644 index 0000000000..46ef8043bc --- /dev/null +++ b/progs/glsl/array.c @@ -0,0 +1,261 @@ +/** + * Test variable array indexing in a vertex shader. + * Brian Paul + * 17 April 2009 + */ + +#include <assert.h> +#include <string.h> +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <GL/gl.h> +#include <GL/glut.h> +#include <GL/glext.h> +#include "extfuncs.h" +#include "shaderutil.h" + + +/** + * The vertex position.z is used as a (variable) index into an + * array which returns a new Z value. + */ +static const char *VertShaderText = + "uniform sampler2D tex1; \n" + "uniform float HeightArray[20]; \n" + "void main() \n" + "{ \n" + " vec4 pos = gl_Vertex; \n" + " int i = int(pos.z * 9.5); \n" + " pos.z = HeightArray[i]; \n" + " gl_Position = gl_ModelViewProjectionMatrix * pos; \n" + " gl_FrontColor = pos; \n" + "} \n"; + +static const char *FragShaderText = + "void main() \n" + "{ \n" + " gl_FragColor = gl_Color; \n" + "} \n"; + + +static GLuint fragShader; +static GLuint vertShader; +static GLuint program; + +static GLint win = 0; +static GLboolean Anim = GL_TRUE; +static GLboolean WireFrame = GL_TRUE; +static GLfloat xRot = -70.0f, yRot = 0.0f, zRot = 0.0f; + + +static void +Idle(void) +{ + zRot = 90 + glutGet(GLUT_ELAPSED_TIME) * 0.05; + glutPostRedisplay(); +} + + +/** z=f(x,y) */ +static float +fz(float x, float y) +{ + return fabs(cos(1.5*x) + cos(1.5*y)); +} + + +static void +DrawMesh(void) +{ + GLfloat xmin = -2.0, xmax = 2.0; + GLfloat ymin = -2.0, ymax = 2.0; + GLuint xdivs = 20, ydivs = 20; + GLfloat dx = (xmax - xmin) / xdivs; + GLfloat dy = (ymax - ymin) / ydivs; + GLfloat ds = 1.0 / xdivs, dt = 1.0 / ydivs; + GLfloat x, y, s, t; + GLuint i, j; + + y = ymin; + t = 0.0; + for (i = 0; i < ydivs; i++) { + x = xmin; + s = 0.0; + glBegin(GL_QUAD_STRIP); + for (j = 0; j < xdivs; j++) { + float z0 = fz(x, y), z1 = fz(x, y + dy); + + glTexCoord2f(s, t); + glVertex3f(x, y, z0); + + glTexCoord2f(s, t + dt); + glVertex3f(x, y + dy, z1); + x += dx; + s += ds; + } + glEnd(); + y += dy; + t += dt; + } +} + + +static void +Redisplay(void) +{ + glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); + + if (WireFrame) + glPolygonMode(GL_FRONT_AND_BACK, GL_LINE); + else + glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); + + glPushMatrix(); + glRotatef(xRot, 1.0f, 0.0f, 0.0f); + glRotatef(yRot, 0.0f, 1.0f, 0.0f); + glRotatef(zRot, 0.0f, 0.0f, 1.0f); + + glPushMatrix(); + DrawMesh(); + glPopMatrix(); + + glPopMatrix(); + + glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); + + glutSwapBuffers(); +} + + +static void +Reshape(int width, int height) +{ + glViewport(0, 0, width, height); + glMatrixMode(GL_PROJECTION); + glLoadIdentity(); + glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0); + glMatrixMode(GL_MODELVIEW); + glLoadIdentity(); + glTranslatef(0.0f, 0.0f, -15.0f); +} + + +static void +CleanUp(void) +{ + glDeleteShader_func(fragShader); + glDeleteShader_func(vertShader); + glDeleteProgram_func(program); + glutDestroyWindow(win); +} + + +static void +Key(unsigned char key, int x, int y) +{ + const GLfloat step = 2.0; + (void) x; + (void) y; + + switch(key) { + case 'a': + Anim = !Anim; + if (Anim) + glutIdleFunc(Idle); + else + glutIdleFunc(NULL); + break; + case 'w': + WireFrame = !WireFrame; + break; + case 'z': + zRot += step; + break; + case 'Z': + zRot -= step; + break; + case 27: + CleanUp(); + exit(0); + break; + } + glutPostRedisplay(); +} + + +static void +SpecialKey(int key, int x, int y) +{ + const GLfloat step = 2.0; + + (void) x; + (void) y; + + switch(key) { + case GLUT_KEY_UP: + xRot += step; + break; + case GLUT_KEY_DOWN: + xRot -= step; + break; + case GLUT_KEY_LEFT: + yRot -= step; + break; + case GLUT_KEY_RIGHT: + yRot += step; + break; + } + glutPostRedisplay(); +} + + +static void +Init(void) +{ + GLfloat HeightArray[20]; + GLint u, i; + + if (!ShadersSupported()) + exit(1); + + GetExtensionFuncs(); + + vertShader = CompileShaderText(GL_VERTEX_SHADER, VertShaderText); + fragShader = CompileShaderText(GL_FRAGMENT_SHADER, FragShaderText); + program = LinkShaders(vertShader, fragShader); + + glUseProgram_func(program); + + /* Setup the HeightArray[] uniform */ + for (i = 0; i < 20; i++) + HeightArray[i] = i / 20.0; + u = glGetUniformLocation_func(program, "HeightArray"); + glUniform1fv_func(u, 20, HeightArray); + + assert(glGetError() == 0); + + glClearColor(0.4f, 0.4f, 0.8f, 0.0f); + glEnable(GL_DEPTH_TEST); + glColor3f(1, 1, 1); +} + + +int +main(int argc, char *argv[]) +{ + glutInit(&argc, argv); + glutInitWindowSize(500, 500); + glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); + win = glutCreateWindow(argv[0]); + glutReshapeFunc(Reshape); + glutKeyboardFunc(Key); + glutSpecialFunc(SpecialKey); + glutDisplayFunc(Redisplay); + Init(); + if (Anim) + glutIdleFunc(Idle); + glutMainLoop(); + return 0; +} + |