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/gl.h>
  17 #include <GL/glut.h>
  18 #include <GL/glext.h>
  19 #include "extfuncs.h"
  20 #include "shaderutil.h"
  21
  22
  23 static char *FragProgFile = NULL;
  24 static char *VertProgFile = NULL;
  25 static GLuint fragShader;
  26 static GLuint vertShader;
  27 static GLuint program;
  28 static GLuint SphereList, RectList, CurList;
  29 static GLint win = 0;
  30 static GLboolean anim = GL_TRUE;
  31 static GLfloat xRot = 0.0f, yRot = 0.0f;
  32
  33
  34 static void
  35 Redisplay(void)
  36 {
  37    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  38
  39    glPushMatrix();
  40    glRotatef(xRot, 1.0f, 0.0f, 0.0f);
  41    glRotatef(yRot, 0.0f, 1.0f, 0.0f);
  42    glCallList(CurList);
  43    glPopMatrix();
  44
  45    glutSwapBuffers();
  46 }
  47
  48
  49 static void
  50 Idle(void)
  51 {
  52    yRot = glutGet(GLUT_ELAPSED_TIME) * 0.1;
  53    glutPostRedisplay();
  54 }
  55
  56
  57 static void
  58 Reshape(int width, int height)
  59 {
  60    glViewport(0, 0, width, height);
  61    glMatrixMode(GL_PROJECTION);
  62    glLoadIdentity();
  63    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
  64    glMatrixMode(GL_MODELVIEW);
  65    glLoadIdentity();
  66    glTranslatef(0.0f, 0.0f, -15.0f);
  67 }
  68
  69
  70 static void
  71 CleanUp(void)
  72 {
  73    glDeleteShader_func(fragShader);
  74    glDeleteShader_func(vertShader);
  75    glDeleteProgram_func(program);
  76    glutDestroyWindow(win);
  77 }
  78
  79
  80 static void
  81 Key(unsigned char key, int x, int y)
  82 {
  83   (void) x;
  84   (void) y;
  85
  86    switch(key) {
  87    case ' ':
  88    case 'a':
  89       anim = !anim;
  90       if (anim)
  91          glutIdleFunc(Idle);
  92       else
  93          glutIdleFunc(NULL);
  94       break;
  95    case 'o':
  96       if (CurList == SphereList)
  97          CurList = RectList;
  98       else
  99          CurList = SphereList;
 100       break;
 101    case 27:
 102       CleanUp();
 103       exit(0);
 104       break;
 105    }
 106    glutPostRedisplay();
 107 }
 108
 109
 110 static void
 111 SpecialKey(int key, int x, int y)
 112 {
 113    const GLfloat step = 3.0f;
 114
 115   (void) x;
 116   (void) y;
 117
 118    switch(key) {
 119    case GLUT_KEY_UP:
 120       xRot -= step;
 121       break;
 122    case GLUT_KEY_DOWN:
 123       xRot += step;
 124       break;
 125    case GLUT_KEY_LEFT:
 126       yRot -= step;
 127       break;
 128    case GLUT_KEY_RIGHT:
 129       yRot += step;
 130       break;
 131    }
 132    glutPostRedisplay();
 133 }
 134
 135
 136 static void
 137 MakeSphere(void)
 138 {
 139    GLUquadricObj *obj = gluNewQuadric();
 140    SphereList = glGenLists(1);
 141    gluQuadricTexture(obj, GL_TRUE);
 142    glNewList(SphereList, GL_COMPILE);
 143    gluSphere(obj, 2.0f, 30, 15);
 144    glEndList();
 145 }
 146
 147
 148 static void
 149 MakeRect(void)
 150 {
 151    RectList = glGenLists(1);
 152    glNewList(RectList, GL_COMPILE);
 153    glBegin(GL_POLYGON);
 154    glTexCoord2f(0, 0);   glVertex2f(-2, -2);
 155    glTexCoord2f(1, 0);   glVertex2f( 2, -2);
 156    glTexCoord2f(1, 1);   glVertex2f( 2,  2);
 157    glTexCoord2f(0, 1);   glVertex2f(-2,  2);
 158    glEnd();
 159    glEndList();
 160 }
 161
 162
 163 static void
 164 Init(void)
 165 {
 166    static const char *fragShaderText =
 167       "void main() {\n"
 168       "   gl_FragColor = abs(dFdy(gl_TexCoord[0])) * 50.0;\n"
 169       "  // gl_FragColor = gl_TexCoord[0];\n"
 170       "}\n";
 171    static const char *vertShaderText =
 172       "void main() {\n"
 173       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 174       "   gl_TexCoord[0] = gl_MultiTexCoord0;\n"
 175       "}\n";
 176
 177    if (!ShadersSupported())
 178       exit(1);
 179
 180    GetExtensionFuncs();
 181
 182    vertShader = CompileShaderText(GL_VERTEX_SHADER, vertShaderText);
 183    fragShader = CompileShaderText(GL_FRAGMENT_SHADER, fragShaderText);
 184    program = LinkShaders(vertShader, fragShader);
 185
 186    glUseProgram_func(program);
 187
 188    /*assert(glGetError() == 0);*/
 189
 190    glClearColor(0.3f, 0.3f, 0.3f, 0.0f);
 191    glEnable(GL_DEPTH_TEST);
 192
 193    MakeSphere();
 194    MakeRect();
 195
 196    CurList = SphereList;
 197
 198    printf("GL_RENDERER = %s\n",(const char *) glGetString(GL_RENDERER));
 199
 200    assert(glIsProgram_func(program));
 201    assert(glIsShader_func(fragShader));
 202    assert(glIsShader_func(vertShader));
 203
 204    glColor3f(1, 0, 0);
 205 }
 206
 207
 208 static void
 209 ParseOptions(int argc, char *argv[])
 210 {
 211    int i;
 212    for (i = 1; i < argc; i++) {
 213       if (strcmp(argv[i], "-fs") == 0) {
 214          FragProgFile = argv[i+1];
 215       }
 216       else if (strcmp(argv[i], "-vs") == 0) {
 217          VertProgFile = argv[i+1];
 218       }
 219    }
 220 }
 221
 222
 223 int
 224 main(int argc, char *argv[])
 225 {
 226    glutInit(&argc, argv);
 227    glutInitWindowPosition( 0, 0);
 228    glutInitWindowSize(200, 200);
 229    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 230    win = glutCreateWindow(argv[0]);
 231    glutReshapeFunc(Reshape);
 232    glutKeyboardFunc(Key);
 233    glutSpecialFunc(SpecialKey);
 234    glutDisplayFunc(Redisplay);
 235    if (anim)
 236       glutIdleFunc(Idle);
 237    ParseOptions(argc, argv);
 238    Init();
 239    glutMainLoop();
 240    return 0;
 241 }