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    glutSwapBuffers();
  78 }
  79
  80
  81 static void
  82 Reshape(int width, int height)
  83 {
  84    glViewport(0, 0, width, height);
  85    glMatrixMode(GL_PROJECTION);
  86    glLoadIdentity();
  87    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  88    glMatrixMode(GL_MODELVIEW);
  89    glLoadIdentity();
  90    glTranslatef(0.0f, 0.0f, -6.0f);
  91 }
  92
  93
  94 static void
  95 CleanUp(void)
  96 {
  97    glDeleteShader_func(fragShader);
  98    glDeleteShader_func(vertShader);
  99    glDeleteProgram_func(program);
 100    glutDestroyWindow(win);
 101 }
 102
 103
 104 static void
 105 Key(unsigned char key, int x, int y)
 106 {
 107   (void) x;
 108   (void) y;
 109
 110    switch(key) {
 111    case 'z':
 112       zoom *= 0.9;
 113       break;
 114    case 'Z':
 115       zoom /= 0.9;
 116       break;
 117    case 27:
 118       CleanUp();
 119       exit(0);
 120       break;
 121    }
 122    glutPostRedisplay();
 123 }
 124
 125
 126 static void
 127 SpecialKey(int key, int x, int y)
 128 {
 129    const GLfloat step = 0.1 * zoom;
 130
 131   (void) x;
 132   (void) y;
 133
 134    switch(key) {
 135    case GLUT_KEY_UP:
 136       yCenter += step;
 137       break;
 138    case GLUT_KEY_DOWN:
 139       yCenter -= step;
 140       break;
 141    case GLUT_KEY_LEFT:
 142       xCenter -= step;
 143       break;
 144    case GLUT_KEY_RIGHT:
 145       xCenter += step;
 146       break;
 147    }
 148    glutPostRedisplay();
 149 }
 150
 151
 152 static void
 153 Init(void)
 154 {
 155    if (!ShadersSupported())
 156       exit(1);
 157
 158    GetExtensionFuncs();
 159
 160    vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
 161    fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
 162    program = LinkShaders(vertShader, fragShader);
 163
 164    glUseProgram_func(program);
 165
 166    InitUniforms(program, Uniforms);
 167
 168    uZoom = glGetUniformLocation_func(program, "Zoom");
 169    uXcenter = glGetUniformLocation_func(program, "Xcenter");
 170    uYcenter = glGetUniformLocation_func(program, "Ycenter");
 171
 172    assert(glGetError() == 0);
 173
 174    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 175
 176    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 177
 178    assert(glIsProgram_func(program));
 179    assert(glIsShader_func(fragShader));
 180    assert(glIsShader_func(vertShader));
 181
 182    glColor3f(1, 0, 0);
 183 }
 184
 185
 186 static void
 187 ParseOptions(int argc, char *argv[])
 188 {
 189    int i;
 190    for (i = 1; i < argc; i++) {
 191       if (strcmp(argv[i], "-fs") == 0) {
 192          FragProgFile = argv[i+1];
 193       }
 194       else if (strcmp(argv[i], "-vs") == 0) {
 195          VertProgFile = argv[i+1];
 196       }
 197    }
 198 }
 199
 200
 201 int
 202 main(int argc, char *argv[])
 203 {
 204    glutInit(&argc, argv);
 205    glutInitWindowPosition( 0, 0);
 206    glutInitWindowSize(400, 400);
 207    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 208    win = glutCreateWindow(argv[0]);
 209    glutReshapeFunc(Reshape);
 210    glutKeyboardFunc(Key);
 211    glutSpecialFunc(SpecialKey);
 212    glutDisplayFunc(Redisplay);
 213    ParseOptions(argc, argv);
 214    Init();
 215    glutMainLoop();
 216    return 0;
 217 }
 218