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/glew.h>
  13 #include <GL/glut.h>
  14 #include "shaderutil.h"
  15
  16
  17 static char *FragProgFile = "CH18-mandel.frag";
  18 static char *VertProgFile = "CH18-mandel.vert";
  19
  20 /* program/shader objects */
  21 static GLuint fragShader;
  22 static GLuint vertShader;
  23 static GLuint program;
  24
  25
  26 static struct uniform_info Uniforms[] = {
  27    /* vert */
  28    { "LightPosition",        1, GL_FLOAT_VEC3, { 0.1, 0.1, 9.0, 0}, -1 },
  29    { "SpecularContribution", 1, GL_FLOAT, { 0.5, 0, 0, 0 }, -1 },
  30    { "DiffuseContribution",  1, GL_FLOAT, { 0.5, 0, 0, 0 }, -1 },
  31    { "Shininess",            1, GL_FLOAT, { 20.0, 0, 0, 0 }, -1 },
  32    /* frag */
  33    { "MaxIterations",        1, GL_FLOAT, { 12, 0, 0, 0 }, -1 },
  34    { "Zoom",                 1, GL_FLOAT, { 0.125, 0, 0, 0 }, -1 },
  35    { "Xcenter",              1, GL_FLOAT, { -1.5, 0, 0, 0 }, -1 },
  36    { "Ycenter",              1, GL_FLOAT, { .005, 0, 0, 0 }, -1 },
  37    { "InnerColor",           1, GL_FLOAT_VEC3, { 1, 0, 0, 0 }, -1 },
  38    { "OuterColor1",          1, GL_FLOAT_VEC3, { 0, 1, 0, 0 }, -1 },
  39    { "OuterColor2",          1, GL_FLOAT_VEC3, { 0, 0, 1, 0 }, -1 },
  40    END_OF_UNIFORMS
  41 };
  42
  43 static GLint win = 0;
  44
  45 static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
  46
  47 static GLint uZoom, uXcenter, uYcenter;
  48 static GLfloat zoom = 1.0, xCenter = -1.5, yCenter = 0.0;
  49
  50
  51 static void
  52 Redisplay(void)
  53 {
  54    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  55
  56    /* set interactive uniform parameters */
  57    glUniform1fv(uZoom, 1, &zoom);
  58    glUniform1fv(uXcenter, 1, &xCenter);
  59    glUniform1fv(uYcenter, 1, &yCenter);
  60
  61    glPushMatrix();
  62    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  63    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  64    glRotatef(zRot, 0.0f, 0.0f, 1.0f);
  65
  66    glBegin(GL_POLYGON);
  67    glTexCoord2f(0, 0);   glVertex2f(-1, -1);
  68    glTexCoord2f(1, 0);   glVertex2f( 1, -1);
  69    glTexCoord2f(1, 1);   glVertex2f( 1,  1);
  70    glTexCoord2f(0, 1);   glVertex2f(-1,  1);
  71    glEnd();
  72
  73    glPopMatrix();
  74
  75    glutSwapBuffers();
  76 }
  77
  78
  79 static void
  80 Reshape(int width, int height)
  81 {
  82    glViewport(0, 0, width, height);
  83    glMatrixMode(GL_PROJECTION);
  84    glLoadIdentity();
  85    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  86    glMatrixMode(GL_MODELVIEW);
  87    glLoadIdentity();
  88    glTranslatef(0.0f, 0.0f, -6.0f);
  89 }
  90
  91
  92 static void
  93 CleanUp(void)
  94 {
  95    glDeleteShader(fragShader);
  96    glDeleteShader(vertShader);
  97    glDeleteProgram(program);
  98    glutDestroyWindow(win);
  99 }
 100
 101
 102 static void
 103 Key(unsigned char key, int x, int y)
 104 {
 105   (void) x;
 106   (void) y;
 107
 108    switch(key) {
 109    case 'z':
 110       zoom *= 0.9;
 111       break;
 112    case 'Z':
 113       zoom /= 0.9;
 114       break;
 115    case 27:
 116       CleanUp();
 117       exit(0);
 118       break;
 119    }
 120    glutPostRedisplay();
 121 }
 122
 123
 124 static void
 125 SpecialKey(int key, int x, int y)
 126 {
 127    const GLfloat step = 0.1 * zoom;
 128
 129   (void) x;
 130   (void) y;
 131
 132    switch(key) {
 133    case GLUT_KEY_UP:
 134       yCenter += step;
 135       break;
 136    case GLUT_KEY_DOWN:
 137       yCenter -= step;
 138       break;
 139    case GLUT_KEY_LEFT:
 140       xCenter -= step;
 141       break;
 142    case GLUT_KEY_RIGHT:
 143       xCenter += step;
 144       break;
 145    }
 146    glutPostRedisplay();
 147 }
 148
 149
 150 static void
 151 Init(void)
 152 {
 153    if (!ShadersSupported())
 154       exit(1);
 155
 156    vertShader = CompileShaderFile(GL_VERTEX_SHADER, VertProgFile);
 157    fragShader = CompileShaderFile(GL_FRAGMENT_SHADER, FragProgFile);
 158    program = LinkShaders(vertShader, fragShader);
 159
 160    glUseProgram(program);
 161
 162    SetUniformValues(program, Uniforms);
 163    PrintUniforms(Uniforms);
 164
 165    uZoom = glGetUniformLocation(program, "Zoom");
 166    uXcenter = glGetUniformLocation(program, "Xcenter");
 167    uYcenter = glGetUniformLocation(program, "Ycenter");
 168
 169    assert(glGetError() == 0);
 170
 171    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 172
 173    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 174
 175    assert(glIsProgram(program));
 176    assert(glIsShader(fragShader));
 177    assert(glIsShader(vertShader));
 178
 179    glColor3f(1, 0, 0);
 180 }
 181
 182
 183 static void
 184 ParseOptions(int argc, char *argv[])
 185 {
 186    int i;
 187    for (i = 1; i < argc; i++) {
 188       if (strcmp(argv[i], "-fs") == 0) {
 189          FragProgFile = argv[i+1];
 190       }
 191       else if (strcmp(argv[i], "-vs") == 0) {
 192          VertProgFile = argv[i+1];
 193       }
 194    }
 195 }
 196
 197
 198 int
 199 main(int argc, char *argv[])
 200 {
 201    glutInit(&argc, argv);
 202    glutInitWindowSize(400, 400);
 203    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 204    win = glutCreateWindow(argv[0]);
 205    glewInit();
 206    glutReshapeFunc(Reshape);
 207    glutKeyboardFunc(Key);
 208    glutSpecialFunc(SpecialKey);
 209    glutDisplayFunc(Redisplay);
 210    ParseOptions(argc, argv);
 211    Init();
 212    glutMainLoop();
 213    return 0;
 214 }
 215