| /** |
| * Test GLSL gl_FragCoord fragment program attribute. |
| * Color the quad's fragments according to their window position. |
| * |
| * Brian Paul |
| * 20 Nov 2008 |
| */ |
| |
| |
| #include <assert.h> |
| #include <string.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <math.h> |
| #include <GL/glew.h> |
| #include <GL/glut.h> |
| #include "shaderutil.h" |
| |
| |
| static GLint WinWidth = 200, WinHeight = 200; |
| static char *FragProgFile = NULL; |
| static char *VertProgFile = NULL; |
| static GLuint fragShader; |
| static GLuint vertShader; |
| static GLuint program; |
| static GLint win = 0; |
| static GLboolean Anim = GL_TRUE; |
| static GLfloat PosX = 0.0, PosY = 0.0; |
| |
| |
| static void |
| Idle(void) |
| { |
| float r = (WinWidth < WinHeight) ? WinWidth : WinHeight; |
| float a = glutGet(GLUT_ELAPSED_TIME) * 0.001; |
| r *= 0.25; |
| PosX = WinWidth / 2 + r * cos(a); |
| PosY = WinHeight / 2 + r * sin(a); |
| |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| Redisplay(void) |
| { |
| glClear(GL_COLOR_BUFFER_BIT); |
| |
| glPushMatrix(); |
| glTranslatef(PosX, PosY, 0.0); |
| #if 0 |
| glBegin(GL_POLYGON); |
| glVertex2f(-50, -50); |
| glVertex2f( 50, -50); |
| glVertex2f( 50, 50); |
| glVertex2f(-50, 50); |
| glEnd(); |
| #else |
| glutSolidSphere(50, 20, 10); |
| #endif |
| glPopMatrix(); |
| |
| glutSwapBuffers(); |
| } |
| |
| |
| static void |
| Reshape(int width, int height) |
| { |
| glViewport(0, 0, width, height); |
| glMatrixMode(GL_PROJECTION); |
| glLoadIdentity(); |
| glOrtho(0, width, 0, height, -55, 55); |
| |
| glMatrixMode(GL_MODELVIEW); |
| glLoadIdentity(); |
| |
| WinWidth = width; |
| WinHeight = height; |
| } |
| |
| |
| static void |
| CleanUp(void) |
| { |
| glDeleteShader(fragShader); |
| glDeleteShader(vertShader); |
| glDeleteProgram(program); |
| glutDestroyWindow(win); |
| } |
| |
| |
| static void |
| Key(unsigned char key, int x, int y) |
| { |
| (void) x; |
| (void) y; |
| |
| switch(key) { |
| case ' ': |
| case 'a': |
| Anim = !Anim; |
| glutIdleFunc(Anim ? Idle : NULL); |
| break; |
| case 27: |
| CleanUp(); |
| exit(0); |
| break; |
| } |
| glutPostRedisplay(); |
| } |
| |
| |
| static void |
| Init(void) |
| { |
| static const char *fragShaderText = |
| "void main() { \n" |
| " vec4 scale = vec4(.005, 0.005, 0.5, 1.0);\n" |
| " gl_FragColor = gl_FragCoord * scale; \n" |
| "}\n"; |
| static const char *vertShaderText = |
| "void main() {\n" |
| " gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n" |
| "}\n"; |
| |
| if (!ShadersSupported()) |
| exit(1); |
| |
| vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText); |
| fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText); |
| program = LinkShaders(vertShader, fragShader); |
| |
| glUseProgram(program); |
| |
| /*assert(glGetError() == 0);*/ |
| |
| glClearColor(0.3f, 0.3f, 0.3f, 0.0f); |
| |
| printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER)); |
| |
| assert(glIsProgram(program)); |
| assert(glIsShader(fragShader)); |
| assert(glIsShader(vertShader)); |
| |
| glColor3f(1, 0, 0); |
| } |
| |
| |
| static void |
| ParseOptions(int argc, char *argv[]) |
| { |
| int i; |
| for (i = 1; i < argc; i++) { |
| if (strcmp(argv[i], "-fs") == 0) { |
| FragProgFile = argv[i+1]; |
| } |
| else if (strcmp(argv[i], "-vs") == 0) { |
| VertProgFile = argv[i+1]; |
| } |
| } |
| } |
| |
| |
| int |
| main(int argc, char *argv[]) |
| { |
| glutInit(&argc, argv); |
| glutInitWindowSize(WinWidth, WinHeight); |
| glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE); |
| win = glutCreateWindow(argv[0]); |
| glewInit(); |
| glutReshapeFunc(Reshape); |
| glutKeyboardFunc(Key); |
| glutDisplayFunc(Redisplay); |
| ParseOptions(argc, argv); |
| Init(); |
| glutIdleFunc(Anim ? Idle : NULL); |
| glutMainLoop(); |
| return 0; |
| } |