330 lines
8.6 KiB
C
330 lines
8.6 KiB
C
/*
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* Use GL_ARB_fragment_shader and GL_ARB_vertex_shader to implement
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* simple per-pixel lighting.
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*
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* Michal Krol
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* 20 February 2006
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*
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* Based on the original demo by:
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* Brian Paul
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* 17 April 2003
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*/
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#ifdef WIN32
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#include <windows.h>
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/gl.h>
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#include <GL/glut.h>
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#include <GL/glext.h>
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#ifdef WIN32
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#define GETPROCADDRESS wglGetProcAddress
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#else
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#define GETPROCADDRESS glutGetProcAddress
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#endif
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static GLfloat diffuse[4] = { 0.5f, 0.5f, 1.0f, 1.0f };
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static GLfloat specular[4] = { 0.8f, 0.8f, 0.8f, 1.0f };
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static GLfloat lightPos[4] = { 0.0f, 10.0f, 20.0f, 1.0f };
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static GLfloat delta = 1.0f;
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static GLhandleARB fragShader;
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static GLhandleARB vertShader;
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static GLhandleARB program;
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static GLint uLightPos;
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static GLint uDiffuse;
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static GLint uSpecular;
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static GLboolean anim = GL_TRUE;
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static GLboolean wire = GL_FALSE;
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static GLboolean pixelLight = GL_TRUE;
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static GLint t0 = 0;
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static GLint frames = 0;
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static GLfloat xRot = 0.0f, yRot = 0.0f;
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static PFNGLCREATESHADEROBJECTARBPROC glCreateShaderObjectARB = NULL;
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static PFNGLSHADERSOURCEARBPROC glShaderSourceARB = NULL;
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static PFNGLCOMPILESHADERARBPROC glCompileShaderARB = NULL;
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static PFNGLCREATEPROGRAMOBJECTARBPROC glCreateProgramObjectARB = NULL;
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static PFNGLATTACHOBJECTARBPROC glAttachObjectARB = NULL;
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static PFNGLLINKPROGRAMARBPROC glLinkProgramARB = NULL;
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static PFNGLUSEPROGRAMOBJECTARBPROC glUseProgramObjectARB = NULL;
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static PFNGLGETUNIFORMLOCATIONARBPROC glGetUniformLocationARB = NULL;
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static PFNGLUNIFORM3FVARBPROC glUniform3fvARB = NULL;
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static PFNGLUNIFORM3FVARBPROC glUniform4fvARB = NULL;
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static void normalize (GLfloat *dst, const GLfloat *src)
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{
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GLfloat len = sqrt (src[0] * src[0] + src[1] * src[1] + src[2] * src[2]);
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dst[0] = src[0] / len;
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dst[1] = src[1] / len;
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dst[2] = src[2] / len;
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}
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static void Redisplay (void)
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{
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glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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if (pixelLight)
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{
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GLfloat vec[3];
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glUseProgramObjectARB (program);
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normalize (vec, lightPos);
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glUniform3fvARB (uLightPos, 1, vec);
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glDisable(GL_LIGHTING);
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}
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else
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{
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glUseProgramObjectARB (0);
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glLightfv (GL_LIGHT0, GL_POSITION, lightPos);
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glEnable(GL_LIGHTING);
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}
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glPushMatrix ();
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glRotatef (xRot, 1.0f, 0.0f, 0.0f);
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glRotatef (yRot, 0.0f, 1.0f, 0.0f);
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glutSolidSphere (2.0, 10, 5);
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glPopMatrix ();
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glutSwapBuffers();
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frames++;
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if (anim)
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{
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GLint t = glutGet (GLUT_ELAPSED_TIME);
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if (t - t0 >= 5000)
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{
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GLfloat seconds = (GLfloat) (t - t0) / 1000.0f;
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GLfloat fps = frames / seconds;
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printf ("%d frames in %6.3f seconds = %6.3f FPS\n", frames, seconds, fps);
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fflush(stdout);
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t0 = t;
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frames = 0;
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}
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}
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}
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static void Idle (void)
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{
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lightPos[0] += delta;
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if (lightPos[0] > 25.0f || lightPos[0] < -25.0f)
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delta = -delta;
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glutPostRedisplay ();
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}
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static void Reshape (int width, int height)
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{
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glViewport (0, 0, width, height);
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glMatrixMode (GL_PROJECTION);
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glLoadIdentity ();
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glFrustum (-1.0, 1.0, -1.0, 1.0, 5.0, 25.0);
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glMatrixMode (GL_MODELVIEW);
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glLoadIdentity ();
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glTranslatef (0.0f, 0.0f, -15.0f);
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}
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static void Key (unsigned char key, int x, int y)
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{
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(void) x;
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(void) y;
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switch (key)
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{
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case ' ':
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case 'a':
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anim = !anim;
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if (anim)
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glutIdleFunc (Idle);
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else
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glutIdleFunc (NULL);
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break;
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case 'x':
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lightPos[0] -= 1.0f;
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break;
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case 'X':
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lightPos[0] += 1.0f;
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break;
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case 'w':
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wire = !wire;
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if (wire)
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glPolygonMode (GL_FRONT_AND_BACK, GL_LINE);
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else
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glPolygonMode (GL_FRONT_AND_BACK, GL_FILL);
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break;
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case 'p':
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pixelLight = !pixelLight;
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if (pixelLight)
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printf ("Per-pixel lighting\n");
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else
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printf ("Conventional lighting\n");
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break;
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case 27:
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exit(0);
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break;
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}
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glutPostRedisplay ();
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}
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static void SpecialKey (int key, int x, int y)
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{
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const GLfloat step = 3.0f;
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(void) x;
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(void) y;
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switch (key)
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{
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case GLUT_KEY_UP:
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xRot -= step;
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break;
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case GLUT_KEY_DOWN:
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xRot += step;
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break;
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case GLUT_KEY_LEFT:
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yRot -= step;
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break;
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case GLUT_KEY_RIGHT:
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yRot += step;
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break;
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}
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glutPostRedisplay ();
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}
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static void Init (void)
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{
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static const char *fragShaderText =
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"uniform vec3 lightPos;\n"
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"uniform vec4 diffuse;\n"
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"uniform vec4 specular;\n"
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"varying vec3 normal;\n"
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"void main () {\n"
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" // Compute dot product of light direction and normal vector\n"
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" float dotProd = max (dot (lightPos, normalize (normal)), 0.0);\n"
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" // Compute diffuse and specular contributions\n"
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#if 1
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" gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
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#elif 1 /* test IF/ELSE/ENDIF */
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" if (normal.y > 0.0) { \n"
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" gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
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" } \n"
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" else { \n"
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" if (normal.x < 0.0) { \n"
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" gl_FragColor = vec4(1, 0, 0, 0); \n"
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" } \n"
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" else { \n"
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" gl_FragColor = vec4(1, 1, 0, 0); \n"
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" } \n"
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" } \n"
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#elif 1 /* test LOOP */
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" while (1) { \n"
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" if (normal.y >= 0.0) { \n"
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" gl_FragColor = vec4(1, 0, 0, 0); \n"
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" break; \n"
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" } else { \n"
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" gl_FragColor = diffuse * dotProd + specular * pow (dotProd, 20.0);\n"
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" break; \n"
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" } \n"
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" } \n"
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#endif
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"}\n"
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;
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static const char *vertShaderText =
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"varying vec3 normal;\n"
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"void main () {\n"
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" gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;\n"
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" normal = gl_NormalMatrix * gl_Normal;\n"
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"}\n"
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;
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if (!glutExtensionSupported ("GL_ARB_fragment_shader"))
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{
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printf ("Sorry, this demo requires GL_ARB_fragment_shader\n");
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exit(1);
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}
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if (!glutExtensionSupported ("GL_ARB_shader_objects"))
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{
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printf ("Sorry, this demo requires GL_ARB_shader_objects\n");
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exit(1);
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}
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if (!glutExtensionSupported ("GL_ARB_shading_language_100"))
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{
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printf ("Sorry, this demo requires GL_ARB_shading_language_100\n");
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exit(1);
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}
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if (!glutExtensionSupported ("GL_ARB_vertex_shader"))
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{
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printf ("Sorry, this demo requires GL_ARB_vertex_shader\n");
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exit(1);
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}
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glCreateShaderObjectARB = (PFNGLCREATESHADEROBJECTARBPROC) GETPROCADDRESS ("glCreateShaderObjectARB");
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glShaderSourceARB = (PFNGLSHADERSOURCEARBPROC) GETPROCADDRESS ("glShaderSourceARB");
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glCompileShaderARB = (PFNGLCOMPILESHADERARBPROC) GETPROCADDRESS ("glCompileShaderARB");
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glCreateProgramObjectARB = (PFNGLCREATEPROGRAMOBJECTARBPROC) GETPROCADDRESS ("glCreateProgramObjectARB");
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glAttachObjectARB = (PFNGLATTACHOBJECTARBPROC) GETPROCADDRESS ("glAttachObjectARB");
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glLinkProgramARB = (PFNGLLINKPROGRAMARBPROC) GETPROCADDRESS ("glLinkProgramARB");
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glUseProgramObjectARB = (PFNGLUSEPROGRAMOBJECTARBPROC) GETPROCADDRESS ("glUseProgramObjectARB");
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glGetUniformLocationARB = (PFNGLGETUNIFORMLOCATIONARBPROC) GETPROCADDRESS ("glGetUniformLocationARB");
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glUniform3fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform3fvARB");
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glUniform4fvARB = (PFNGLUNIFORM3FVARBPROC) GETPROCADDRESS ("glUniform4fvARB");
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fragShader = glCreateShaderObjectARB (GL_FRAGMENT_SHADER_ARB);
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glShaderSourceARB (fragShader, 1, &fragShaderText, NULL);
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glCompileShaderARB (fragShader);
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vertShader = glCreateShaderObjectARB (GL_VERTEX_SHADER_ARB);
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glShaderSourceARB (vertShader, 1, &vertShaderText, NULL);
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glCompileShaderARB (vertShader);
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program = glCreateProgramObjectARB ();
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glAttachObjectARB (program, fragShader);
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glAttachObjectARB (program, vertShader);
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glLinkProgramARB (program);
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glUseProgramObjectARB (program);
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uLightPos = glGetUniformLocationARB (program, "lightPos");
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uDiffuse = glGetUniformLocationARB (program, "diffuse");
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uSpecular = glGetUniformLocationARB (program, "specular");
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glUniform4fvARB (uDiffuse, 1, diffuse);
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glUniform4fvARB (uSpecular, 1, specular);
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glClearColor (0.3f, 0.3f, 0.3f, 0.0f);
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glEnable (GL_DEPTH_TEST);
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glEnable (GL_LIGHT0);
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glEnable (GL_LIGHTING);
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glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, diffuse);
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glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, specular);
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glMaterialf (GL_FRONT_AND_BACK, GL_SHININESS, 20.0f);
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printf ("GL_RENDERER = %s\n", (const char *) glGetString (GL_RENDERER));
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printf ("Press p to toggle between per-pixel and per-vertex lighting\n");
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}
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int main (int argc, char *argv[])
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{
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glutInit (&argc, argv);
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glutInitWindowPosition ( 0, 0);
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glutInitWindowSize (200, 200);
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glutInitDisplayMode (GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
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glutCreateWindow (argv[0]);
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glutReshapeFunc (Reshape);
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glutKeyboardFunc (Key);
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glutSpecialFunc (SpecialKey);
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glutDisplayFunc (Redisplay);
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if (anim)
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glutIdleFunc (Idle);
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Init ();
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glutMainLoop ();
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return 0;
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}
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