src/glsl/noise2.c

   1 /*
   2  * GLSL noise demo.
   3  *
   4  * Michal Krol
   5  * 20 February 2006
   6  *
   7  * Based on the original demo by:
   8  * Stefan Gustavson (stegu@itn.liu.se) 2004, 2005
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <glad/glad.h>
  14 #include "glut_wrap.h"
  15
  16
  17 static GLhandleARB fragShader;
  18 static GLhandleARB vertShader;
  19 static GLhandleARB program;
  20
  21 static GLint uTime;
  22
  23 static GLint t0 = 0;
  24 static GLint frames = 0;
  25
  26 static GLfloat u_time = 0.0f;
  27
  28 static void
  29 Redisplay(void)
  30 {
  31    GLint t;
  32
  33    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  34
  35    glUniform1fARB(uTime, 0.5f * u_time);
  36
  37    glPushMatrix();
  38    glutSolidSphere(2.0, 20, 10);
  39    glPopMatrix();
  40
  41    glutSwapBuffers();
  42    frames++;
  43
  44    t = glutGet(GLUT_ELAPSED_TIME);
  45    if (t - t0 >= 5000) {
  46       GLfloat seconds = (GLfloat) (t - t0) / 1000.0f;
  47       GLfloat fps = frames / seconds;
  48       printf("%d frames in %6.3f seconds = %6.3f FPS\n", frames, seconds,
  49              fps);
  50       fflush(stdout);
  51       t0 = t;
  52       frames = 0;
  53    }
  54 }
  55
  56 static void
  57 Idle(void)
  58 {
  59    u_time += 0.1f;
  60    glutPostRedisplay();
  61 }
  62
  63 static void
  64 Reshape(int width, int height)
  65 {
  66    glViewport(0, 0, width, height);
  67    glMatrixMode(GL_PROJECTION);
  68    glLoadIdentity();
  69    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  70    glMatrixMode(GL_MODELVIEW);
  71    glLoadIdentity();
  72    glTranslatef(0.0f, 0.0f, -15.0f);
  73 }
  74
  75 static void
  76 Key(unsigned char key, int x, int y)
  77 {
  78    (void) x;
  79    (void) y;
  80
  81    switch (key) {
  82    case 27:
  83       exit(0);
  84       break;
  85    }
  86    glutPostRedisplay();
  87 }
  88
  89 static void
  90 Init(void)
  91 {
  92    static const char *fragShaderText =
  93       "uniform float time;\n"
  94       "varying vec3 position;\n"
  95       "void main () {\n"
  96       "   gl_FragColor = vec4 (vec3 (0.5 + 0.5 * noise1 (vec4 (position, time))), 1.0);\n"
  97       "}\n";
  98    static const char *vertShaderText =
  99       "varying vec3 position;\n"
 100       "void main () {\n"
 101       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 102       "   position = 4.0 * gl_Vertex.xyz;\n" "}\n";
 103
 104    if (!glutExtensionSupported("GL_ARB_fragment_shader")) {
 105       printf("Sorry, this demo requires GL_ARB_fragment_shader\n");
 106       exit(1);
 107    }
 108    if (!glutExtensionSupported("GL_ARB_shader_objects")) {
 109       printf("Sorry, this demo requires GL_ARB_shader_objects\n");
 110       exit(1);
 111    }
 112    if (!glutExtensionSupported("GL_ARB_shading_language_100")) {
 113       printf("Sorry, this demo requires GL_ARB_shading_language_100\n");
 114       exit(1);
 115    }
 116    if (!glutExtensionSupported("GL_ARB_vertex_shader")) {
 117       printf("Sorry, this demo requires GL_ARB_vertex_shader\n");
 118       exit(1);
 119    }
 120
 121    fragShader = glCreateShaderObjectARB(GL_FRAGMENT_SHADER_ARB);
 122    glShaderSourceARB(fragShader, 1, &fragShaderText, NULL);
 123    glCompileShaderARB(fragShader);
 124
 125    vertShader = glCreateShaderObjectARB(GL_VERTEX_SHADER_ARB);
 126    glShaderSourceARB(vertShader, 1, &vertShaderText, NULL);
 127    glCompileShaderARB(vertShader);
 128
 129    program = glCreateProgramObjectARB();
 130    glAttachObjectARB(program, fragShader);
 131    glAttachObjectARB(program, vertShader);
 132    glLinkProgramARB(program);
 133    glUseProgramObjectARB(program);
 134
 135    uTime = glGetUniformLocationARB(program, "time");
 136
 137    glClearColor(0.0f, 0.1f, 0.3f, 1.0f);
 138    glEnable(GL_CULL_FACE);
 139    glEnable(GL_DEPTH_TEST);
 140
 141    printf("GL_RENDERER = %s\n", (const char *) glGetString(GL_RENDERER));
 142 }
 143
 144 int
 145 main(int argc, char *argv[])
 146 {
 147    glutInit(&argc, argv);
 148    glutInitWindowSize(200, 200);
 149    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 150    glutCreateWindow(argv[0]);
 151    glutReshapeFunc(Reshape);
 152    glutKeyboardFunc(Key);
 153    glutDisplayFunc(Redisplay);
 154    glutIdleFunc(Idle);
 155    gladLoadGL();
 156    Init();
 157    glutMainLoop();
 158    return 0;
 159 }