progs/glsl/deriv.c

   1 /**
   2  * Test OpenGL 2.0 dx/dy functions for texcoords.
   3  * Brian Paul
   4  * 2 May 2007
   5  *
   6  * NOTE: resize the window to observe how the partial derivatives of
   7  * the texcoords change.
   8  */
   9
  10
  11 #include <assert.h>
  12 #include <string.h>
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <math.h>
  16 #include <GL/glew.h>
  17 #include <GL/glut.h>
  18 #include "shaderutil.h"
  19
  20
  21 static char *FragProgFile = NULL;
  22 static char *VertProgFile = NULL;
  23 static GLuint fragShader;
  24 static GLuint vertShader;
  25 static GLuint program;
  26 static GLuint SphereList, RectList, CurList;
  27 static GLint win = 0;
  28 static GLboolean anim = GL_TRUE;
  29 static GLfloat xRot = 0.0f, yRot = 0.0f;
  30 static GLint WinSize[2];
  31 static GLint WinSizeUniform = -1;
  32
  33
  34 static void
  35 Redisplay(void)
  36 {
  37    glUniform2iv(WinSizeUniform, 1, WinSize);
  38
  39    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  40
  41    glPushMatrix();
  42    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  43    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  44    glCallList(CurList);
  45    glPopMatrix();
  46
  47    glutSwapBuffers();
  48 }
  49
  50
  51 static void
  52 Idle(void)
  53 {
  54    yRot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  55    glutPostRedisplay();
  56 }
  57
  58
  59 static void
  60 Reshape(int width, int height)
  61 {
  62    WinSize[0] = width;
  63    WinSize[1] = height;
  64    glViewport(0, 0, width, height);
  65    glMatrixMode(GL_PROJECTION);
  66    glLoadIdentity();
  67    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  68    glMatrixMode(GL_MODELVIEW);
  69    glLoadIdentity();
  70    glTranslatef(0.0f, 0.0f, -15.0f);
  71 }
  72
  73
  74 static void
  75 CleanUp(void)
  76 {
  77    glDeleteShader(fragShader);
  78    glDeleteShader(vertShader);
  79    glDeleteProgram(program);
  80    glutDestroyWindow(win);
  81 }
  82
  83
  84 static void
  85 Key(unsigned char key, int x, int y)
  86 {
  87   (void) x;
  88   (void) y;
  89
  90    switch(key) {
  91    case ' ':
  92    case 'a':
  93       anim = !anim;
  94       if (anim)
  95          glutIdleFunc(Idle);
  96       else
  97          glutIdleFunc(NULL);
  98       break;
  99    case 'o':
 100       if (CurList == SphereList)
 101          CurList = RectList;
 102       else
 103          CurList = SphereList;
 104       break;
 105    case 27:
 106       CleanUp();
 107       exit(0);
 108       break;
 109    }
 110    glutPostRedisplay();
 111 }
 112
 113
 114 static void
 115 SpecialKey(int key, int x, int y)
 116 {
 117    const GLfloat step = 3.0f;
 118
 119   (void) x;
 120   (void) y;
 121
 122    switch(key) {
 123    case GLUT_KEY_UP:
 124       xRot -= step;
 125       break;
 126    case GLUT_KEY_DOWN:
 127       xRot += step;
 128       break;
 129    case GLUT_KEY_LEFT:
 130       yRot -= step;
 131       break;
 132    case GLUT_KEY_RIGHT:
 133       yRot += step;
 134       break;
 135    }
 136    glutPostRedisplay();
 137 }
 138
 139
 140 static void
 141 MakeSphere(void)
 142 {
 143    GLUquadricObj *obj = gluNewQuadric();
 144    SphereList = glGenLists(1);
 145    gluQuadricTexture(obj, GL_TRUE);
 146    glNewList(SphereList, GL_COMPILE);
 147    gluSphere(obj, 2.0f, 30, 15);
 148    glEndList();
 149    gluDeleteQuadric(obj);
 150 }
 151
 152
 153 static void
 154 MakeRect(void)
 155 {
 156    RectList = glGenLists(1);
 157    glNewList(RectList, GL_COMPILE);
 158    glBegin(GL_POLYGON);
 159    glTexCoord2f(0, 0);   glVertex2f(-2, -2);
 160    glTexCoord2f(1, 0);   glVertex2f( 2, -2);
 161    glTexCoord2f(1, 1);   glVertex2f( 2,  2);
 162    glTexCoord2f(0, 1);   glVertex2f(-2,  2);
 163    glEnd();
 164    glEndList();
 165 }
 166
 167
 168 static void
 169 Init(void)
 170 {
 171    static const char *fragShaderText =
 172       "uniform ivec2 WinSize; \n"
 173       "void main() {\n"
 174       "   vec2 d = dFdy(gl_TexCoord[0].xy) * vec2(WinSize); \n"
 175       "   gl_FragColor =  vec4(d.x, d.y, 0.0, 1.0);\n"
 176       "  // gl_FragColor = gl_TexCoord[0];\n"
 177       "}\n";
 178    static const char *vertShaderText =
 179       "void main() {\n"
 180       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 181       "   gl_TexCoord[0] = gl_MultiTexCoord0;\n"
 182       "}\n";
 183
 184    if (!ShadersSupported())
 185       exit(1);
 186
 187    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 188    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 189    program = LinkShaders(vertShader, fragShader);
 190
 191    glUseProgram(program);
 192    WinSizeUniform = glGetUniformLocation(program, "WinSize");
 193
 194    /*assert(glGetError() == 0);*/
 195
 196    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 197    glEnable(GL_DEPTH_TEST);
 198
 199    MakeSphere();
 200    MakeRect();
 201
 202    CurList = SphereList;
 203
 204    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 205
 206    assert(glIsProgram(program));
 207    assert(glIsShader(fragShader));
 208    assert(glIsShader(vertShader));
 209
 210    glColor3f(1, 0, 0);
 211 }
 212
 213
 214 static void
 215 ParseOptions(int argc, char *argv[])
 216 {
 217    int i;
 218    for (i = 1; i < argc; i++) {
 219       if (strcmp(argv[i], "-fs") == 0) {
 220          FragProgFile = argv[i+1];
 221       }
 222       else if (strcmp(argv[i], "-vs") == 0) {
 223          VertProgFile = argv[i+1];
 224       }
 225    }
 226 }
 227
 228
 229 int
 230 main(int argc, char *argv[])
 231 {
 232    WinSize[0] = WinSize[1] = 200;
 233
 234    glutInit(&argc, argv);
 235    glutInitWindowSize(WinSize[0], WinSize[1]);
 236    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 237    win = glutCreateWindow(argv[0]);
 238    glewInit();
 239    glutReshapeFunc(Reshape);
 240    glutKeyboardFunc(Key);
 241    glutSpecialFunc(SpecialKey);
 242    glutDisplayFunc(Redisplay);
 243    if (anim)
 244       glutIdleFunc(Idle);
 245    ParseOptions(argc, argv);
 246    Init();
 247    glutMainLoop();
 248    return 0;
 249 }