added progs/demos/fragcoord.c - tests gl_FragCoord attribute in fragment shader
Fragment's red/greenb/blue is a function gl_FragCoord.xyz
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Brian Paul
parent
7e97362884
commit
80301866f6
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@ -16,6 +16,7 @@ PROGS = \
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convolutions \
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deriv \
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identity \
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fragcoord \
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mandelbrot \
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multitex \
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noise \
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@ -115,6 +116,13 @@ identity: identity.o shaderutil.o
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$(APP_CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) identity.o shaderutil.o $(LIBS) -o $@
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fragcoord.o: fragcoord.c extfuncs.h shaderutil.h
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$(CC) -c -I$(INCDIR) $(CFLAGS) fragcoord.c
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fragcoord: fragcoord.o shaderutil.o
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$(CC) -I$(INCDIR) $(CFLAGS) $(LDFLAGS) fragcoord.o shaderutil.o $(LIBS) -o $@
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mandelbrot.o: mandelbrot.c extfuncs.h shaderutil.h
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$(APP_CC) -c -I$(INCDIR) $(CFLAGS) mandelbrot.c
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@ -0,0 +1,185 @@
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/**
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* Test GLSL gl_FragCoord fragment program attribute.
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* Color the quad's fragments according to their window position.
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*
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* Brian Paul
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* 20 Nov 2008
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*/
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#include <assert.h>
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#include <string.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/gl.h>
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#include <GL/glut.h>
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#include <GL/glext.h>
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#include "extfuncs.h"
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#include "shaderutil.h"
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static GLint WinWidth = 200, WinHeight = 200;
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static char *FragProgFile = NULL;
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static char *VertProgFile = NULL;
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static GLuint fragShader;
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static GLuint vertShader;
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static GLuint program;
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static GLint win = 0;
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static GLboolean Anim = GL_TRUE;
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static GLfloat PosX = 0.0, PosY = 0.0;
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static void
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Idle(void)
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{
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float r = (WinWidth < WinHeight) ? WinWidth : WinHeight;
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float a = glutGet(GLUT_ELAPSED_TIME) * 0.001;
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r *= 0.25;
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PosX = WinWidth / 2 + r * cos(a);
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PosY = WinHeight / 2 + r * sin(a);
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glutPostRedisplay();
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}
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static void
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Redisplay(void)
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{
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glClear(GL_COLOR_BUFFER_BIT);
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glPushMatrix();
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glTranslatef(PosX, PosY, 0.0);
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#if 0
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glBegin(GL_POLYGON);
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glVertex2f(-50, -50);
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glVertex2f( 50, -50);
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glVertex2f( 50, 50);
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glVertex2f(-50, 50);
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glEnd();
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#else
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glutSolidSphere(50, 20, 10);
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#endif
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glPopMatrix();
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glutSwapBuffers();
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}
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static void
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Reshape(int width, int height)
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{
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glOrtho(0, width, 0, height, -55, 55);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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WinWidth = width;
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WinHeight = height;
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}
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static void
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CleanUp(void)
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{
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glDeleteShader_func(fragShader);
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glDeleteShader_func(vertShader);
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glDeleteProgram_func(program);
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glutDestroyWindow(win);
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}
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static void
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Key(unsigned char key, int x, int y)
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{
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(void) x;
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(void) y;
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switch(key) {
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case ' ':
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case 'a':
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Anim = !Anim;
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glutIdleFunc(Anim ? Idle : NULL);
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break;
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case 27:
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CleanUp();
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void
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Init(void)
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{
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static const char *fragShaderText =
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"void main() { \n"
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" vec4 scale = vec4(.005, 0.005, 0.5, 1.0);\n"
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" gl_FragColor = gl_FragCoord * scale; \n"
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"}\n";
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static const char *vertShaderText =
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"void main() {\n"
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" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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"}\n";
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if (!ShadersSupported())
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exit(1);
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GetExtensionFuncs();
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vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
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fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
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program = LinkShaders(vertShader, fragShader);
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glUseProgram_func(program);
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/*assert(glGetError() == 0);*/
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glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
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printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
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assert(glIsProgram_func(program));
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assert(glIsShader_func(fragShader));
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assert(glIsShader_func(vertShader));
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glColor3f(1, 0, 0);
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}
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static void
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ParseOptions(int argc, char *argv[])
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{
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int i;
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for (i = 1; i < argc; i++) {
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if (strcmp(argv[i], "-fs") == 0) {
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FragProgFile = argv[i+1];
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}
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else if (strcmp(argv[i], "-vs") == 0) {
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VertProgFile = argv[i+1];
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}
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}
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}
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int
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main(int argc, char *argv[])
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{
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glutInit(&argc, argv);
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glutInitWindowPosition( 0, 0);
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glutInitWindowSize(WinWidth, WinHeight);
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glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
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win = glutCreateWindow(argv[0]);
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutDisplayFunc(Redisplay);
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ParseOptions(argc, argv);
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Init();
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glutIdleFunc(Anim ? Idle : NULL);
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glutMainLoop();
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return 0;
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}
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