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
  31
  32 static void
  33 Redisplay(void)
  34 {
  35    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  36
  37    glPushMatrix();
  38    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  39    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  40    glCallList(CurList);
  41    glPopMatrix();
  42
  43    glutSwapBuffers();
  44 }
  45
  46
  47 static void
  48 Idle(void)
  49 {
  50    yRot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  51    glutPostRedisplay();
  52 }
  53
  54
  55 static void
  56 Reshape(int width, int height)
  57 {
  58    glViewport(0, 0, width, height);
  59    glMatrixMode(GL_PROJECTION);
  60    glLoadIdentity();
  61    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  62    glMatrixMode(GL_MODELVIEW);
  63    glLoadIdentity();
  64    glTranslatef(0.0f, 0.0f, -15.0f);
  65 }
  66
  67
  68 static void
  69 CleanUp(void)
  70 {
  71    glDeleteShader(fragShader);
  72    glDeleteShader(vertShader);
  73    glDeleteProgram(program);
  74    glutDestroyWindow(win);
  75 }
  76
  77
  78 static void
  79 Key(unsigned char key, int x, int y)
  80 {
  81   (void) x;
  82   (void) y;
  83
  84    switch(key) {
  85    case ' ':
  86    case 'a':
  87       anim = !anim;
  88       if (anim)
  89          glutIdleFunc(Idle);
  90       else
  91          glutIdleFunc(NULL);
  92       break;
  93    case 'o':
  94       if (CurList == SphereList)
  95          CurList = RectList;
  96       else
  97          CurList = SphereList;
  98       break;
  99    case 27:
 100       CleanUp();
 101       exit(0);
 102       break;
 103    }
 104    glutPostRedisplay();
 105 }
 106
 107
 108 static void
 109 SpecialKey(int key, int x, int y)
 110 {
 111    const GLfloat step = 3.0f;
 112
 113   (void) x;
 114   (void) y;
 115
 116    switch(key) {
 117    case GLUT_KEY_UP:
 118       xRot -= step;
 119       break;
 120    case GLUT_KEY_DOWN:
 121       xRot += step;
 122       break;
 123    case GLUT_KEY_LEFT:
 124       yRot -= step;
 125       break;
 126    case GLUT_KEY_RIGHT:
 127       yRot += step;
 128       break;
 129    }
 130    glutPostRedisplay();
 131 }
 132
 133
 134 static void
 135 MakeSphere(void)
 136 {
 137    GLUquadricObj *obj = gluNewQuadric();
 138    SphereList = glGenLists(1);
 139    gluQuadricTexture(obj, GL_TRUE);
 140    glNewList(SphereList, GL_COMPILE);
 141    gluSphere(obj, 2.0f, 30, 15);
 142    glEndList();
 143    gluDeleteQuadric(obj);
 144 }
 145
 146
 147 static void
 148 MakeRect(void)
 149 {
 150    RectList = glGenLists(1);
 151    glNewList(RectList, GL_COMPILE);
 152    glBegin(GL_POLYGON);
 153    glTexCoord2f(0, 0);   glVertex2f(-2, -2);
 154    glTexCoord2f(1, 0);   glVertex2f( 2, -2);
 155    glTexCoord2f(1, 1);   glVertex2f( 2,  2);
 156    glTexCoord2f(0, 1);   glVertex2f(-2,  2);
 157    glEnd();
 158    glEndList();
 159 }
 160
 161
 162 static void
 163 Init(void)
 164 {
 165    static const char *fragShaderText =
 166       "void main() {\n"
 167       "   gl_FragColor = abs(dFdy(gl_TexCoord[0])) * 50.0;\n"
 168       "  // gl_FragColor = gl_TexCoord[0];\n"
 169       "}\n";
 170    static const char *vertShaderText =
 171       "void main() {\n"
 172       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 173       "   gl_TexCoord[0] = gl_MultiTexCoord0;\n"
 174       "}\n";
 175
 176    if (!ShadersSupported())
 177       exit(1);
 178
 179    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 180    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 181    program = LinkShaders(vertShader, fragShader);
 182
 183    glUseProgram(program);
 184
 185    /*assert(glGetError() == 0);*/
 186
 187    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 188    glEnable(GL_DEPTH_TEST);
 189
 190    MakeSphere();
 191    MakeRect();
 192
 193    CurList = SphereList;
 194
 195    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 196
 197    assert(glIsProgram(program));
 198    assert(glIsShader(fragShader));
 199    assert(glIsShader(vertShader));
 200
 201    glColor3f(1, 0, 0);
 202 }
 203
 204
 205 static void
 206 ParseOptions(int argc, char *argv[])
 207 {
 208    int i;
 209    for (i = 1; i < argc; i++) {
 210       if (strcmp(argv[i], "-fs") == 0) {
 211          FragProgFile = argv[i+1];
 212       }
 213       else if (strcmp(argv[i], "-vs") == 0) {
 214          VertProgFile = argv[i+1];
 215       }
 216    }
 217 }
 218
 219
 220 int
 221 main(int argc, char *argv[])
 222 {
 223    glutInit(&argc, argv);
 224    glutInitWindowSize(200, 200);
 225    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 226    win = glutCreateWindow(argv[0]);
 227    glewInit();
 228    glutReshapeFunc(Reshape);
 229    glutKeyboardFunc(Key);
 230    glutSpecialFunc(SpecialKey);
 231    glutDisplayFunc(Redisplay);
 232    if (anim)
 233       glutIdleFunc(Idle);
 234    ParseOptions(argc, argv);
 235    Init();
 236    glutMainLoop();
 237    return 0;
 238 }