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