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 #include "shaderutil.h"
  17
  18
  19 static char *FragProgFile = "CH18-mandel.frag";
  20 static char *VertProgFile = "CH18-mandel.vert";
  21
  22 /* program/shader objects */
  23 static GLuint fragShader;
  24 static GLuint vertShader;
  25 static GLuint program;
  26
  27
  28 static struct uniform_info Uniforms[] = {
  29    /* vert */
  30    { "LightPosition",        3, GL_FLOAT, { 0.1, 0.1, 9.0, 0}, -1 },
  31    { "SpecularContribution", 1, GL_FLOAT, { 0.5, 0, 0, 0 }, -1 },
  32    { "DiffuseContribution",  1, GL_FLOAT, { 0.5, 0, 0, 0 }, -1 },
  33    { "Shininess",            1, GL_FLOAT, { 20.0, 0, 0, 0 }, -1 },
  34    /* frag */
  35    { "MaxIterations",        1, GL_FLOAT, { 12, 0, 0, 0 }, -1 },
  36    { "Zoom",                 1, GL_FLOAT, { 0.125, 0, 0, 0 }, -1 },
  37    { "Xcenter",              1, GL_FLOAT, { -1.5, 0, 0, 0 }, -1 },
  38    { "Ycenter",              1, GL_FLOAT, { .005, 0, 0, 0 }, -1 },
  39    { "InnerColor",           3, GL_FLOAT, { 1, 0, 0, 0 }, -1 },
  40    { "OuterColor1",          3, GL_FLOAT, { 0, 1, 0, 0 }, -1 },
  41    { "OuterColor2",          3, GL_FLOAT, { 0, 0, 1, 0 }, -1 },
  42    END_OF_UNIFORMS
  43 };
  44
  45 static GLint win = 0;
  46
  47 static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
  48
  49 static GLint uZoom, uXcenter, uYcenter;
  50 static GLfloat zoom = 1.0, xCenter = -1.5, yCenter = 0.0;
  51
  52
  53 static void
  54 Redisplay(void)
  55 {
  56    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  57
  58    /* set interactive uniform parameters */
  59    glUniform1fv_func(uZoom, 1, &zoom);
  60    glUniform1fv_func(uXcenter, 1, &xCenter);
  61    glUniform1fv_func(uYcenter, 1, &yCenter);
  62
  63    glPushMatrix();
  64    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  65    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  66    glRotatef(zRot, 0.0f, 0.0f, 1.0f);
  67
  68    glBegin(GL_POLYGON);
  69    glTexCoord2f(0, 0);   glVertex2f(-1, -1);
  70    glTexCoord2f(1, 0);   glVertex2f( 1, -1);
  71    glTexCoord2f(1, 1);   glVertex2f( 1,  1);
  72    glTexCoord2f(0, 1);   glVertex2f(-1,  1);
  73    glEnd();
  74
  75    glPopMatrix();
  76
  77    glFinish();
  78    glFlush();
  79    glutSwapBuffers();
  80 }
  81
  82
  83 static void
  84 Reshape(int width, int height)
  85 {
  86    glViewport(0, 0, width, height);
  87    glMatrixMode(GL_PROJECTION);
  88    glLoadIdentity();
  89    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  90    glMatrixMode(GL_MODELVIEW);
  91    glLoadIdentity();
  92    glTranslatef(0.0f, 0.0f, -6.0f);
  93 }
  94
  95
  96 static void
  97 CleanUp(void)
  98 {
  99    glDeleteShader_func(fragShader);
 100    glDeleteShader_func(vertShader);
 101    glDeleteProgram_func(program);
 102    glutDestroyWindow(win);
 103 }
 104
 105
 106 static void
 107 Key(unsigned char key, int x, int y)
 108 {
 109   (void) x;
 110   (void) y;
 111
 112    switch(key) {
 113    case 'z':
 114       zoom *= 0.9;
 115       break;
 116    case 'Z':
 117       zoom /= 0.9;
 118       break;
 119    case 27:
 120       CleanUp();
 121       exit(0);
 122       break;
 123    }
 124    glutPostRedisplay();
 125 }
 126
 127
 128 static void
 129 SpecialKey(int key, int x, int y)
 130 {
 131    const GLfloat step = 0.1 * zoom;
 132
 133   (void) x;
 134   (void) y;
 135
 136    switch(key) {
 137    case GLUT_KEY_UP:
 138       yCenter += step;
 139       break;
 140    case GLUT_KEY_DOWN:
 141       yCenter -= step;
 142       break;
 143    case GLUT_KEY_LEFT:
 144       xCenter -= step;
 145       break;
 146    case GLUT_KEY_RIGHT:
 147       xCenter += step;
 148       break;
 149    }
 150    glutPostRedisplay();
 151 }
 152
 153
 154 static void
 155 Init(void)
 156 {
 157    if (!ShadersSupported())
 158       exit(1);
 159
 160    GetExtensionFuncs();
 161
 162    vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
 163    fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
 164    program = LinkShaders(vertShader, fragShader);
 165
 166    glUseProgram_func(program);
 167
 168    InitUniforms(program, Uniforms);
 169
 170    uZoom = glGetUniformLocation_func(program, "Zoom");
 171    uXcenter = glGetUniformLocation_func(program, "Xcenter");
 172    uYcenter = glGetUniformLocation_func(program, "Ycenter");
 173
 174    assert(glGetError() == 0);
 175
 176    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 177
 178    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 179
 180    assert(glIsProgram_func(program));
 181    assert(glIsShader_func(fragShader));
 182    assert(glIsShader_func(vertShader));
 183
 184    glColor3f(1, 0, 0);
 185 }
 186
 187
 188 static void
 189 ParseOptions(int argc, char *argv[])
 190 {
 191    int i;
 192    for (i = 1; i < argc; i++) {
 193       if (strcmp(argv[i], "-fs") == 0) {
 194          FragProgFile = argv[i+1];
 195       }
 196       else if (strcmp(argv[i], "-vs") == 0) {
 197          VertProgFile = argv[i+1];
 198       }
 199    }
 200 }
 201
 202
 203 int
 204 main(int argc, char *argv[])
 205 {
 206    glutInit(&argc, argv);
 207    glutInitWindowPosition( 0, 0);
 208    glutInitWindowSize(400, 400);
 209    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 210    win = glutCreateWindow(argv[0]);
 211    glutReshapeFunc(Reshape);
 212    glutKeyboardFunc(Key);
 213    glutSpecialFunc(SpecialKey);
 214    glutDisplayFunc(Redisplay);
 215    ParseOptions(argc, argv);
 216    Init();
 217    glutMainLoop();
 218    return 0;
 219 }
 220