src/glsl/simplex-noise.c

   1 /**
   2  * Test/demo of Ian McEwan's simplex noise function.
   3  * See https://github.com/ashima/webgl-noise
   4  *
   5  * Brian Paul
   6  * 17 March 2011
   7  */
   8
   9 #include <assert.h>
  10 #include <string.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <math.h>
  14 #include <GL/glew.h>
  15 #include "glut_wrap.h"
  16 #include "shaderutil.h"
  17
  18
  19 static const char *VertShaderText =
  20    "void main() {\n"
  21    "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
  22    "   gl_TexCoord[0] = gl_MultiTexCoord0;\n"
  23    "}\n";
  24
  25 static const char *FragShaderMainText =
  26    "uniform float Slice;\n"
  27    "void main()\n"
  28    "{\n"
  29    "   vec3 c = vec3(3.0 * gl_TexCoord[0].xy, Slice);\n"
  30    "   float r = simplexNoise3(c); \n"
  31    "   gl_FragColor = vec4(r, r, r, 1.0);;\n"
  32    "}\n";
  33
  34
  35 static struct uniform_info Uniforms[] = {
  36    { "pParam",   1, GL_FLOAT_VEC4, { 17*17, 3, 2, 3 }, -1 },
  37    { "Slice",    1, GL_FLOAT, { 0.5, 0, 0, 0}, -1 },
  38    END_OF_UNIFORMS
  39 };
  40
  41 /* program/shader objects */
  42 static GLuint fragShader;
  43 static GLuint vertShader;
  44 static GLuint program;
  45
  46 static GLint win = 0;
  47 static GLfloat xRot = 0.0f, yRot = 0.0f, zRot = 0.0f;
  48 static GLfloat Slice = 0.0;
  49 static GLboolean Anim = GL_TRUE;
  50 static GLint ParamUniform = -1, SliceUniform = -1;
  51
  52
  53 static void
  54 Idle(void)
  55 {
  56    Slice = glutGet(GLUT_ELAPSED_TIME) * 0.001;
  57    glutPostRedisplay();
  58 }
  59
  60
  61 static void
  62 Redisplay(void)
  63 {
  64    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  65
  66    glUniform1f(SliceUniform, Slice);
  67
  68    glPushMatrix();
  69    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  70    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  71    glRotatef(zRot, 0.0f, 0.0f, 1.0f);
  72
  73    glBegin(GL_POLYGON);
  74    glTexCoord2f(0, 0);   glVertex2f(-2, -2);
  75    glTexCoord2f(1, 0);   glVertex2f( 2, -2);
  76    glTexCoord2f(1, 1);   glVertex2f( 2,  2);
  77    glTexCoord2f(0, 1);   glVertex2f(-2,  2);
  78    glEnd();
  79
  80    glPopMatrix();
  81
  82    glutSwapBuffers();
  83 }
  84
  85
  86 static void
  87 Reshape(int width, int height)
  88 {
  89    glViewport(0, 0, width, height);
  90    glMatrixMode(GL_PROJECTION);
  91    glLoadIdentity();
  92    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  93    glMatrixMode(GL_MODELVIEW);
  94    glLoadIdentity();
  95    glTranslatef(0.0f, 0.0f, -15.0f);
  96 }
  97
  98
  99 static void
 100 CleanUp(void)
 101 {
 102    glDeleteShader(fragShader);
 103    glDeleteShader(vertShader);
 104    glDeleteProgram(program);
 105    glutDestroyWindow(win);
 106 }
 107
 108
 109 static void
 110 Key(unsigned char key, int x, int y)
 111 {
 112    const GLfloat step = 1.0;//0.01;
 113   (void) x;
 114   (void) y;
 115
 116    switch(key) {
 117    case 'a':
 118       Anim = !Anim;
 119       glutIdleFunc(Anim ? Idle : NULL);
 120       break;
 121    case 's':
 122       Slice -= step;
 123       break;
 124    case 'S':
 125       Slice += step;
 126       break;
 127    case 'z':
 128       zRot -= 1.0;
 129       break;
 130    case 'Z':
 131       zRot += 1.0;
 132       break;
 133    case 27:
 134       CleanUp();
 135       exit(0);
 136       break;
 137    }
 138    glutPostRedisplay();
 139 }
 140
 141
 142 static void
 143 SpecialKey(int key, int x, int y)
 144 {
 145    const GLfloat step = 3.0f;
 146
 147   (void) x;
 148   (void) y;
 149
 150    switch(key) {
 151    case GLUT_KEY_UP:
 152       xRot -= step;
 153       break;
 154    case GLUT_KEY_DOWN:
 155       xRot += step;
 156       break;
 157    case GLUT_KEY_LEFT:
 158       yRot -= step;
 159       break;
 160    case GLUT_KEY_RIGHT:
 161       yRot += step;
 162       break;
 163    }
 164    glutPostRedisplay();
 165 }
 166
 167
 168
 169 static void
 170 Init(void)
 171 {
 172    const char *filename = "simplex-noise.glsl";
 173    char noiseText[10000];
 174    FILE *f;
 175    int len;
 176
 177    f = fopen(filename, "r");
 178    if (!f) {
 179       fprintf(stderr, "Unable to open %s\n", filename);
 180       exit(1);
 181    }
 182
 183    len = fread(noiseText, 1, sizeof(noiseText), f);
 184    fclose(f);
 185
 186    /* append main() code onto buffer */
 187    strcpy(noiseText + len, FragShaderMainText);
 188
 189    if (!ShadersSupported())
 190       exit(1);
 191
 192    vertShader = CompileShaderText(GL_VERTEX_SHADER, VertShaderText);
 193    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, noiseText);
 194    program = LinkShaders(vertShader, fragShader);
 195
 196    glUseProgram(program);
 197
 198    ParamUniform = glGetUniformLocation(program, "pParam");
 199    SliceUniform = glGetUniformLocation(program, "Slice");
 200
 201    SetUniformValues(program, Uniforms);
 202    PrintUniforms(Uniforms);
 203
 204    assert(glGetError() == 0);
 205
 206    glClearColor(0.4f, 0.4f, 0.8f, 0.0f);
 207
 208    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 209
 210    assert(glIsProgram(program));
 211    assert(glIsShader(fragShader));
 212    assert(glIsShader(vertShader));
 213
 214    glColor3f(1, 0, 0);
 215 }
 216
 217
 218 int
 219 main(int argc, char *argv[])
 220 {
 221    glutInit(&argc, argv);
 222    glutInitWindowSize(400, 400);
 223    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 224    win = glutCreateWindow(argv[0]);
 225    glewInit();
 226    glutReshapeFunc(Reshape);
 227    glutKeyboardFunc(Key);
 228    glutSpecialFunc(SpecialKey);
 229    glutDisplayFunc(Redisplay);
 230    glutIdleFunc(Anim ? Idle : NULL);
 231    Init();
 232    glutMainLoop();
 233    return 0;
 234 }
 235