progs/trivial/fs-tri.c

   1 /* Test fragment shader */
   2
   3 #include <assert.h>
   4 #include <string.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <math.h>
   8 #include <GL/gl.h>
   9 #include <GL/glut.h>
  10 #include <GL/glext.h>
  11 #include "extfuncs.h"
  12
  13
  14 static GLuint fragShader;
  15 static GLuint vertShader;
  16 static GLuint program;
  17 static GLint win = 0;
  18 static GLfloat xpos = 0, ypos = 0;
  19
  20
  21 static void
  22 Redisplay(void)
  23 {
  24    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  25
  26    glPushMatrix();
  27    glTranslatef(xpos, ypos, 0);
  28
  29    glBegin(GL_TRIANGLES);
  30    glColor3f(1, 0, 0);
  31    glVertex2f(-0.9, -0.9);
  32    glColor3f(0, 1, 0);
  33    glVertex2f( 0.9, -0.9);
  34    glColor3f(0, 0, 1);
  35    glVertex2f( 0,  0.9);
  36    glEnd();
  37
  38    glPopMatrix();
  39
  40    glutSwapBuffers();
  41 }
  42
  43
  44 static void
  45 Reshape(int width, int height)
  46 {
  47    glViewport(0, 0, width, height);
  48    glMatrixMode(GL_PROJECTION);
  49    glLoadIdentity();
  50    glOrtho(-1, 1, -1, 1, -1, 1);
  51    glMatrixMode(GL_MODELVIEW);
  52    glLoadIdentity();
  53 }
  54
  55
  56 static void
  57 CleanUp(void)
  58 {
  59    glDeleteShader_func(fragShader);
  60    glDeleteShader_func(vertShader);
  61    glDeleteProgram_func(program);
  62    glutDestroyWindow(win);
  63 }
  64
  65
  66 static void
  67 Key(unsigned char key, int x, int y)
  68 {
  69   (void) x;
  70   (void) y;
  71
  72    switch(key) {
  73    case 27:
  74       CleanUp();
  75       exit(0);
  76       break;
  77    }
  78    glutPostRedisplay();
  79 }
  80
  81
  82 static void
  83 SpecialKey(int key, int x, int y)
  84 {
  85    const GLfloat step = 0.1;
  86
  87   (void) x;
  88   (void) y;
  89
  90    switch(key) {
  91    case GLUT_KEY_UP:
  92       ypos += step;
  93       break;
  94    case GLUT_KEY_DOWN:
  95       ypos -= step;
  96       break;
  97    case GLUT_KEY_LEFT:
  98       xpos -= step;
  99       break;
 100    case GLUT_KEY_RIGHT:
 101       xpos += step;
 102       break;
 103    }
 104    glutPostRedisplay();
 105 }
 106
 107
 108 static void
 109 LoadAndCompileShader(GLuint shader, const char *text)
 110 {
 111    GLint stat;
 112
 113    glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
 114
 115    glCompileShader_func(shader);
 116
 117    glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
 118    if (!stat) {
 119       GLchar log[1000];
 120       GLsizei len;
 121       glGetShaderInfoLog_func(shader, 1000, &len, log);
 122       fprintf(stderr, "fslight: problem compiling shader:\n%s\n", log);
 123       exit(1);
 124    }
 125 }
 126
 127
 128 static void
 129 CheckLink(GLuint prog)
 130 {
 131    GLint stat;
 132    glGetProgramiv_func(prog, GL_LINK_STATUS, &stat);
 133    if (!stat) {
 134       GLchar log[1000];
 135       GLsizei len;
 136       glGetProgramInfoLog_func(prog, 1000, &len, log);
 137       fprintf(stderr, "Linker error:\n%s\n", log);
 138    }
 139 }
 140
 141
 142 static void
 143 Init(void)
 144 {
 145    /* fragment color is a function of fragment position: */
 146    static const char *fragShaderText =
 147       "void main() {\n"
 148       "   gl_FragColor = gl_FragCoord * vec4(0.005); \n"
 149       "   //gl_FragColor = gl_Color; \n"
 150       "   //gl_FragColor = vec4(1, 0, 0.5, 0); \n"
 151       "}\n";
 152 #if 0
 153    static const char *vertShaderText =
 154       "varying vec3 normal;\n"
 155       "void main() {\n"
 156       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 157       "   normal = gl_NormalMatrix * gl_Normal;\n"
 158       "}\n";
 159 #endif
 160    const char *version;
 161
 162    version = (const char *) glGetString(GL_VERSION);
 163    if (version[0] != '2' || version[1] != '.') {
 164       printf("This program requires OpenGL 2.x, found %s\n", version);
 165       exit(1);
 166    }
 167
 168    GetExtensionFuncs();
 169
 170    fragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
 171    LoadAndCompileShader(fragShader, fragShaderText);
 172
 173 #if 0
 174    vertShader = glCreateShader_func(GL_VERTEX_SHADER);
 175    LoadAndCompileShader(vertShader, vertShaderText);
 176 #endif
 177
 178    program = glCreateProgram_func();
 179    glAttachShader_func(program, fragShader);
 180 #if 0
 181    glAttachShader_func(program, vertShader);
 182 #endif
 183    glLinkProgram_func(program);
 184    CheckLink(program);
 185    glUseProgram_func(program);
 186
 187    assert(glGetError() == 0);
 188
 189    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 190
 191    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 192 }
 193
 194
 195 int
 196 main(int argc, char *argv[])
 197 {
 198    glutInit(&argc, argv);
 199    glutInitWindowPosition( 0, 0);
 200    glutInitWindowSize(200, 200);
 201    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 202    win = glutCreateWindow(argv[0]);
 203    glutReshapeFunc(Reshape);
 204    glutKeyboardFunc(Key);
 205    glutSpecialFunc(SpecialKey);
 206    glutDisplayFunc(Redisplay);
 207    Init();
 208    glutMainLoop();
 209    return 0;
 210 }
 211
 212