progs/glsl/mandelbrot.c

   1 /**
   2  * "Mandelbrot" shader demo.  Uses the example shaders from
   3  * chapter 15 (or 18) of the OpenGL Shading Language "orange" book.
   4  * 15 Jan 2007
   5  */
   6
   7 #include <assert.h>
   8 #include <string.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <math.h>
  12 #include <GL/gl.h>
  13 #include <GL/glut.h>
  14 #include <GL/glext.h>
  15 #include "extfuncs.h"
  16
  17
  18 static char *FragProgFile = "CH18-mandel.frag.txt";
  19 static char *VertProgFile = "CH18-mandel.vert.txt";
  20
  21 /* program/shader objects */
  22 static GLuint fragShader;
  23 static GLuint vertShader;
  24 static GLuint program;
  25
  26
  27 struct uniform_info {
  28    const char *name;
  29    GLuint size;
  30    GLint location;
  31    GLfloat value[4];
  32 };
  33
  34 static struct uniform_info Uniforms[] = {
  35    /* vert */
  36    { "LightPosition",        3, -1, { 0.1, 0.1, 9.0, 0} },
  37    { "SpecularContribution", 1, -1, { 0.5, 0, 0, 0 } },
  38    { "DiffuseContribution",  1, -1, { 0.5, 0, 0, 0 } },
  39    { "Shininess",            1, -1, { 20.0, 0, 0, 0 } },
  40    /* frag */
  41    { "MaxIterations",        1, -1, { 12, 0, 0, 0 } },
  42    { "Zoom",                 1, -1, { 0.125, 0, 0, 0 } },
  43    { "Xcenter",              1, -1, { -1.5, 0, 0, 0 } },
  44    { "Ycenter",              1, -1, { .005, 0, 0, 0 } },
  45    { "InnerColor",           3, -1, { 1, 0, 0, 0 } },
  46    { "OuterColor1",          3, -1, { 0, 1, 0, 0 } },
  47    { "OuterColor2",          3, -1, { 0, 0, 1, 0 } },
  48    { NULL, 0, 0, { 0, 0, 0, 0 } }
  49 };
  50
  51 static GLint win = 0;
  52
  53 static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
  54
  55 static GLint uZoom, uXcenter, uYcenter;
  56 static GLfloat zoom = 1.0, xCenter = -1.5, yCenter = 0.0;
  57
  58
  59 static void
  60 Redisplay(void)
  61 {
  62    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  63
  64    /* set interactive uniform parameters */
  65    glUniform1fv_func(uZoom, 1, &zoom);
  66    glUniform1fv_func(uXcenter, 1, &xCenter);
  67    glUniform1fv_func(uYcenter, 1, &yCenter);
  68
  69    glPushMatrix();
  70    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  71    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  72    glRotatef(zRot, 0.0f, 0.0f, 1.0f);
  73
  74    glBegin(GL_POLYGON);
  75    glTexCoord2f(0, 0);   glVertex2f(-1, -1);
  76    glTexCoord2f(1, 0);   glVertex2f( 1, -1);
  77    glTexCoord2f(1, 1);   glVertex2f( 1,  1);
  78    glTexCoord2f(0, 1);   glVertex2f(-1,  1);
  79    glEnd();
  80
  81    glPopMatrix();
  82
  83    glFinish();
  84    glFlush();
  85    glutSwapBuffers();
  86 }
  87
  88
  89 static void
  90 Reshape(int width, int height)
  91 {
  92    glViewport(0, 0, width, height);
  93    glMatrixMode(GL_PROJECTION);
  94    glLoadIdentity();
  95    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  96    glMatrixMode(GL_MODELVIEW);
  97    glLoadIdentity();
  98    glTranslatef(0.0f, 0.0f, -6.0f);
  99 }
 100
 101
 102 static void
 103 CleanUp(void)
 104 {
 105    glDeleteShader_func(fragShader);
 106    glDeleteShader_func(vertShader);
 107    glDeleteProgram_func(program);
 108    glutDestroyWindow(win);
 109 }
 110
 111
 112 static void
 113 Key(unsigned char key, int x, int y)
 114 {
 115   (void) x;
 116   (void) y;
 117
 118    switch(key) {
 119    case 'z':
 120       zoom *= 0.9;
 121       break;
 122    case 'Z':
 123       zoom /= 0.9;
 124       break;
 125    case 27:
 126       CleanUp();
 127       exit(0);
 128       break;
 129    }
 130    glutPostRedisplay();
 131 }
 132
 133
 134 static void
 135 SpecialKey(int key, int x, int y)
 136 {
 137    const GLfloat step = 0.1 * zoom;
 138
 139   (void) x;
 140   (void) y;
 141
 142    switch(key) {
 143    case GLUT_KEY_UP:
 144       yCenter += step;
 145       break;
 146    case GLUT_KEY_DOWN:
 147       yCenter -= step;
 148       break;
 149    case GLUT_KEY_LEFT:
 150       xCenter -= step;
 151       break;
 152    case GLUT_KEY_RIGHT:
 153       xCenter += step;
 154       break;
 155    }
 156    glutPostRedisplay();
 157 }
 158
 159
 160
 161 static void
 162 LoadAndCompileShader(GLuint shader, const char *text)
 163 {
 164    GLint stat;
 165
 166    glShaderSource_func(shader, 1, (const GLchar **) &text, NULL);
 167
 168    glCompileShader_func(shader);
 169
 170    glGetShaderiv_func(shader, GL_COMPILE_STATUS, &stat);
 171    if (!stat) {
 172       GLchar log[1000];
 173       GLsizei len;
 174       glGetShaderInfoLog_func(shader, 1000, &len, log);
 175       fprintf(stderr, "brick: problem compiling shader: %s\n", log);
 176       exit(1);
 177    }
 178    else {
 179       printf("Shader compiled OK\n");
 180    }
 181 }
 182
 183
 184 /**
 185  * Read a shader from a file.
 186  */
 187 static void
 188 ReadShader(GLuint shader, const char *filename)
 189 {
 190    const int max = 100*1000;
 191    int n;
 192    char *buffer = (char*) malloc(max);
 193    FILE *f = fopen(filename, "r");
 194    if (!f) {
 195       fprintf(stderr, "brick: Unable to open shader file %s\n", filename);
 196       exit(1);
 197    }
 198
 199    n = fread(buffer, 1, max, f);
 200    printf("brick: read %d bytes from shader file %s\n", n, filename);
 201    if (n > 0) {
 202       buffer[n] = 0;
 203       LoadAndCompileShader(shader, buffer);
 204    }
 205
 206    fclose(f);
 207    free(buffer);
 208 }
 209
 210
 211 static void
 212 CheckLink(GLuint prog)
 213 {
 214    GLint stat;
 215    glGetProgramiv_func(prog, GL_LINK_STATUS, &stat);
 216    if (!stat) {
 217       GLchar log[1000];
 218       GLsizei len;
 219       glGetProgramInfoLog_func(prog, 1000, &len, log);
 220       fprintf(stderr, "Linker error:\n%s\n", log);
 221    }
 222    else {
 223       fprintf(stderr, "Link success!\n");
 224    }
 225 }
 226
 227
 228 static void
 229 Init(void)
 230 {
 231    const char *version;
 232    GLint i;
 233
 234    version = (const char *) glGetString(GL_VERSION);
 235    if (version[0] != '2' || version[1] != '.') {
 236       printf("Warning: this program expects OpenGL 2.0\n");
 237       /*exit(1);*/
 238    }
 239
 240    GetExtensionFuncs();
 241
 242    vertShader = glCreateShader_func(GL_VERTEX_SHADER);
 243    ReadShader(vertShader, VertProgFile);
 244
 245    fragShader = glCreateShader_func(GL_FRAGMENT_SHADER);
 246    ReadShader(fragShader, FragProgFile);
 247
 248    program = glCreateProgram_func();
 249    glAttachShader_func(program, fragShader);
 250    glAttachShader_func(program, vertShader);
 251    glLinkProgram_func(program);
 252    CheckLink(program);
 253    glUseProgram_func(program);
 254
 255    for (i = 0; Uniforms[i].name; i++) {
 256       Uniforms[i].location
 257          = glGetUniformLocation_func(program, Uniforms[i].name);
 258       printf("Uniform %s location: %d\n", Uniforms[i].name,
 259              Uniforms[i].location);
 260       switch (Uniforms[i].size) {
 261       case 1:
 262          glUniform1fv_func(Uniforms[i].location, 1, Uniforms[i].value);
 263          break;
 264       case 2:
 265          glUniform2fv_func(Uniforms[i].location, 1, Uniforms[i].value);
 266          break;
 267       case 3:
 268          glUniform3fv_func(Uniforms[i].location, 1, Uniforms[i].value);
 269          break;
 270       case 4:
 271          glUniform4fv_func(Uniforms[i].location, 1, Uniforms[i].value);
 272          break;
 273       default:
 274          abort();
 275       }
 276    }
 277
 278    uZoom = glGetUniformLocation_func(program, "Zoom");
 279    uXcenter = glGetUniformLocation_func(program, "Xcenter");
 280    uYcenter = glGetUniformLocation_func(program, "Ycenter");
 281
 282    assert(glGetError() == 0);
 283
 284    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 285
 286    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 287
 288    assert(glIsProgram_func(program));
 289    assert(glIsShader_func(fragShader));
 290    assert(glIsShader_func(vertShader));
 291
 292    glColor3f(1, 0, 0);
 293 }
 294
 295
 296 static void
 297 ParseOptions(int argc, char *argv[])
 298 {
 299    int i;
 300    for (i = 1; i < argc; i++) {
 301       if (strcmp(argv[i], "-fs") == 0) {
 302          FragProgFile = argv[i+1];
 303       }
 304       else if (strcmp(argv[i], "-vs") == 0) {
 305          VertProgFile = argv[i+1];
 306       }
 307    }
 308 }
 309
 310
 311 int
 312 main(int argc, char *argv[])
 313 {
 314    glutInit(&argc, argv);
 315    glutInitWindowPosition( 0, 0);
 316    glutInitWindowSize(400, 400);
 317    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 318    win = glutCreateWindow(argv[0]);
 319    glutReshapeFunc(Reshape);
 320    glutKeyboardFunc(Key);
 321    glutSpecialFunc(SpecialKey);
 322    glutDisplayFunc(Redisplay);
 323    ParseOptions(argc, argv);
 324    Init();
 325    glutMainLoop();
 326    return 0;
 327 }
 328