progs/demos/arbfslight.c

   1 /*
   2  * Use GL_ARB_fragment_shader and GL_ARB_vertex_shader to implement
   3  * simple per-pixel lighting.
   4  *
   5  * Michal Krol
   6  * 20 February 2006
   7  *
   8  * Based on the original demo by:
   9  * Brian Paul
  10  * 17 April 2003
  11  */
  12
  13 #ifdef WIN32
  14 #include <windows.h>
  15 #endif
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <math.h>
  20 #include <GL/gl.h>
  21 #include <GL/glut.h>
  22 #include <GL/glext.h>
  23
  24 #ifdef WIN32
  25 #define GETPROCADDRESS wglGetProcAddress
  26 #else
  27 #define GETPROCADDRESS glutGetProcAddress
  28 #endif
  29
  30 static GLfloat diffuse[4] = { 0.5f, 0.5f, 1.0f, 1.0f };
  31 static GLfloat specular[4] = { 0.8f, 0.8f, 0.8f, 1.0f };
  32 static GLfloat lightPos[4] = { 0.0f, 10.0f, 20.0f, 1.0f };
  33 static GLfloat delta = 1.0f;
  34
  35 static GLhandleARB fragShader;
  36 static GLhandleARB vertShader;
  37 static GLhandleARB program;
  38
  39 static GLint uLightPos;
  40 static GLint uDiffuse;
  41 static GLint uSpecular;
  42
  43 static GLboolean anim = GL_TRUE;
  44 static GLboolean wire = GL_FALSE;
  45 static GLboolean pixelLight = GL_TRUE;
  46
  47 static GLint t0 = 0;
  48 static GLint frames = 0;
  49
  50 static GLfloat xRot = 0.0f, yRot = 0.0f;
  51
  52 static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB = NULL;
  53 static PFNGLSHADERSOURCEARBPROC glShaderSourceARB = NULL;
  54 static PFNGLCOMPILESHADERARBPROC glCompileShaderARB = NULL;
  55 static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB = NULL;
  56 static PFNGLATTACHOBJECTARBPROC glAttachObjectARB = NULL;
  57 static PFNGLLINKPROGRAMARBPROC glLinkProgramARB = NULL;
  58 static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB = NULL;
  59 static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB = NULL;
  60 static PFNGLUNIFORM3FVARBPROC glUniform3fvARB = NULL;
  61 static PFNGLUNIFORM3FVARBPROC glUniform4fvARB = NULL;
  62
  63 static void normalize (GLfloat *dst, const GLfloat *src)
  64 {
  65    GLfloat len = sqrt (src[0] * src[0] + src[1] * src[1] + src[2] * src[2]);
  66    dst[0] = src[0] / len;
  67    dst[1] = src[1] / len;
  68    dst[2] = src[2] / len;
  69 }
  70
  71 static void Redisplay (void)
  72 {
  73         glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  74
  75         if (pixelLight)
  76         {
  77       GLfloat vec[3];
  78
  79                 glUseProgramObjectARB (program);
  80       normalize (vec, lightPos);
  81       glUniform3fvARB (uLightPos, 1, vec);
  82                 glDisable(GL_LIGHTING);
  83         }
  84         else
  85         {
  86                 glUseProgramObjectARB (0);
  87                 glLightfv (GL_LIGHT0, GL_POSITION, lightPos);
  88                 glEnable(GL_LIGHTING);
  89         }
  90
  91         glPushMatrix ();
  92         glRotatef (xRot, 1.0f, 0.0f, 0.0f);
  93         glRotatef (yRot, 0.0f, 1.0f, 0.0f);
  94         glutSolidSphere (2.0, 10, 5);
  95         glPopMatrix ();
  96
  97         glutSwapBuffers();
  98         frames++;
  99
 100         if (anim)
 101         {
 102                 GLint t = glutGet (GLUT_ELAPSED_TIME);
 103                 if (t - t0 >= 5000)
 104                 {
 105                         GLfloat seconds = (GLfloat) (t - t0) / 1000.0f;
 106                         GLfloat fps = frames / seconds;
 107                         printf ("%d frames in %6.3f seconds = %6.3f FPS\n", frames, seconds, fps);
 108                         fflush(stdout);
 109                         t0 = t;
 110                         frames = 0;
 111                 }
 112         }
 113 }
 114
 115 static void Idle (void)
 116 {
 117         lightPos[0] += delta;
 118         if (lightPos[0] > 25.0f || lightPos[0] < -25.0f)
 119                 delta = -delta;
 120         glutPostRedisplay ();
 121 }
 122
 123 static void Reshape (int width, int height)
 124 {
 125         glViewport (0, 0, width, height);
 126         glMatrixMode (GL_PROJECTION);
 127         glLoadIdentity ();
 128         glFrustum (-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
 129         glMatrixMode (GL_MODELVIEW);
 130         glLoadIdentity ();
 131         glTranslatef (0.0f, 0.0f, -15.0f);
 132 }
 133
 134 static void Key (unsigned char key, int x, int y)
 135 {
 136         (void) x;
 137         (void) y;
 138
 139         switch (key)
 140         {
 141         case ' ':
 142         case 'a':
 143                 anim = !anim;
 144                 if (anim)
 145                         glutIdleFunc (Idle);
 146                 else
 147                         glutIdleFunc (NULL);
 148                 break;
 149         case 'x':
 150                 lightPos[0] -= 1.0f;
 151                 break;
 152         case 'X':
 153                 lightPos[0] += 1.0f;
 154                 break;
 155         case 'w':
 156                 wire = !wire;
 157                 if (wire)
 158                         glPolygonMode (GL_FRONT_AND_BACK, GL_LINE);
 159                 else
 160                         glPolygonMode (GL_FRONT_AND_BACK, GL_FILL);
 161                 break;
 162         case 'p':
 163                 pixelLight = !pixelLight;
 164                 if (pixelLight)
 165                         printf ("Per-pixel lighting\n");
 166                 else
 167                         printf ("Conventional lighting\n");
 168                 break;
 169         case 27:
 170                 exit(0);
 171                 break;
 172         }
 173         glutPostRedisplay ();
 174 }
 175
 176 static void SpecialKey (int key, int x, int y)
 177 {
 178         const GLfloat step = 3.0f;
 179
 180         (void) x;
 181         (void) y;
 182
 183         switch (key)
 184         {
 185         case GLUT_KEY_UP:
 186                 xRot -= step;
 187                 break;
 188         case GLUT_KEY_DOWN:
 189                 xRot += step;
 190                 break;
 191         case GLUT_KEY_LEFT:
 192                 yRot -= step;
 193                 break;
 194         case GLUT_KEY_RIGHT:
 195                 yRot += step;
 196                 break;
 197         }
 198         glutPostRedisplay ();
 199 }
 200
 201 static void Init (void)
 202 {
 203    static const char *fragShaderText =
 204       "uniform vec3 lightPos;\n"
 205       "uniform vec4 diffuse;\n"
 206       "uniform vec4 specular;\n"
 207       "varying vec3 normal;\n"
 208       "void main () {\n"
 209       "   // Compute dot product of light direction and normal vector\n"
 210       "   float dotProd = max (dot (lightPos, normalize (normal)), 0.0);\n"
 211       "   // Compute diffuse and specular contributions\n"
 212 #if 1
 213       "   gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
 214 #elif 1 /* test IF/ELSE/ENDIF */
 215       "   if (normal.y > 0.0) { \n"
 216       "      gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
 217       "   } \n"
 218       "   else { \n"
 219       "      if (normal.x < 0.0) { \n"
 220       "         gl_FragColor = vec4(1, 0, 0, 0); \n"
 221       "      } \n"
 222       "      else { \n"
 223       "         gl_FragColor = vec4(1, 1, 0, 0); \n"
 224       "      } \n"
 225       "   } \n"
 226 #elif 1 /* test LOOP */
 227       "   while (1) { \n"
 228       "      if (normal.y >= 0.0) { \n"
 229       "         gl_FragColor = vec4(1, 0, 0, 0); \n"
 230       "         break; \n"
 231       "      } else { \n"
 232       "         gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
 233       "         break; \n"
 234       "      } \n"
 235       "   } \n"
 236 #endif
 237       "}\n"
 238    ;
 239    static const char *vertShaderText =
 240       "varying vec3 normal;\n"
 241       "void main () {\n"
 242       "   gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
 243       "   normal = gl_NormalMatrix * gl_Normal;\n"
 244       "}\n"
 245    ;
 246
 247         if (!glutExtensionSupported ("GL_ARB_fragment_shader"))
 248         {
 249                 printf ("Sorry, this demo requires GL_ARB_fragment_shader\n");
 250                 exit(1);
 251         }
 252         if (!glutExtensionSupported ("GL_ARB_shader_objects"))
 253         {
 254                 printf ("Sorry, this demo requires GL_ARB_shader_objects\n");
 255                 exit(1);
 256         }
 257         if (!glutExtensionSupported ("GL_ARB_shading_language_100"))
 258         {
 259                 printf ("Sorry, this demo requires GL_ARB_shading_language_100\n");
 260                 exit(1);
 261         }
 262         if (!glutExtensionSupported ("GL_ARB_vertex_shader"))
 263         {
 264                 printf ("Sorry, this demo requires GL_ARB_vertex_shader\n");
 265                 exit(1);
 266         }
 267
 268         glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC) GETPROCADDRESS ("glCreateShaderObjectARB");
 269         glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC) GETPROCADDRESS ("glShaderSourceARB");
 270         glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC) GETPROCADDRESS ("glCompileShaderARB");
 271         glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC) GETPROCADDRESS ("glCreateProgramObjectARB");
 272         glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC) GETPROCADDRESS ("glAttachObjectARB");
 273         glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) GETPROCADDRESS ("glLinkProgramARB");
 274         glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) GETPROCADDRESS ("glUseProgramObjectARB");
 275         glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) GETPROCADDRESS ("glGetUniformLocationARB");
 276    glUniform3fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform3fvARB");
 277    glUniform4fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform4fvARB");
 278
 279         fragShader = glCreateShaderObjectARB (GL_FRAGMENT_SHADER_ARB);
 280         glShaderSourceARB (fragShader, 1, &fragShaderText, NULL);
 281         glCompileShaderARB (fragShader);
 282
 283         vertShader = glCreateShaderObjectARB (GL_VERTEX_SHADER_ARB);
 284         glShaderSourceARB (vertShader, 1, &vertShaderText, NULL);
 285         glCompileShaderARB (vertShader);
 286
 287         program = glCreateProgramObjectARB ();
 288         glAttachObjectARB (program, fragShader);
 289         glAttachObjectARB (program, vertShader);
 290         glLinkProgramARB (program);
 291         glUseProgramObjectARB (program);
 292
 293         uLightPos = glGetUniformLocationARB (program, "lightPos");
 294         uDiffuse = glGetUniformLocationARB (program, "diffuse");
 295         uSpecular = glGetUniformLocationARB (program, "specular");
 296
 297    glUniform4fvARB (uDiffuse, 1, diffuse);
 298    glUniform4fvARB (uSpecular, 1, specular);
 299
 300         glClearColor (0.3f, 0.3f, 0.3f, 0.0f);
 301         glEnable (GL_DEPTH_TEST);
 302         glEnable (GL_LIGHT0);
 303         glEnable (GL_LIGHTING);
 304         glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, diffuse);
 305         glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, specular);
 306         glMaterialf (GL_FRONT_AND_BACK, GL_SHININESS, 20.0f);
 307
 308         printf ("GL_RENDERER = %s\n", (const char *) glGetString (GL_RENDERER));
 309         printf ("Press p to toggle between per-pixel and per-vertex lighting\n");
 310 }
 311
 312 int main (int argc, char *argv[])
 313 {
 314         glutInitWindowSize (200, 200);
 315         glutInit (&argc, argv);
 316         glutInitDisplayMode (GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 317         glutCreateWindow (argv[0]);
 318         glutReshapeFunc (Reshape);
 319         glutKeyboardFunc (Key);
 320         glutSpecialFunc (SpecialKey);
 321         glutDisplayFunc (Redisplay);
 322         if (anim)
 323                 glutIdleFunc (Idle);
 324         Init ();
 325         glutMainLoop ();
 326         return 0;
 327 }
 328