273 lines
6.8 KiB
C
273 lines
6.8 KiB
C
|
|
/*
|
|
* GLUT demonstration of texturing with specular highlights.
|
|
*
|
|
* When drawing a lit, textured surface one usually wants the specular
|
|
* highlight to override the texture colors. However, OpenGL applies
|
|
* texturing after lighting so the specular highlight is modulated by
|
|
* the texture.
|
|
*
|
|
* The solution here shown here is a two-pass algorithm:
|
|
* 1. Draw the textured surface without specular lighting.
|
|
* 2. Enable blending to add the next pass:
|
|
* 3. Redraw the surface with a matte white material and only the
|
|
* specular components of light sources enabled.
|
|
*
|
|
* Brian Paul February 1997
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <GL/glut.h>
|
|
|
|
|
|
static GLUquadricObj *Quadric;
|
|
static GLuint Sphere;
|
|
static GLfloat LightPos[4] = {10.0, 10.0, 10.0, 1.0};
|
|
static GLfloat Delta = 20.0;
|
|
static GLint Mode = 4;
|
|
|
|
/*static GLfloat Blue[4] = {0.0, 0.0, 1.0, 1.0};*/
|
|
/*static GLfloat Gray[4] = {0.5, 0.5, 0.5, 1.0};*/
|
|
static GLfloat Black[4] = {0.0, 0.0, 0.0, 1.0};
|
|
static GLfloat White[4] = {1.0, 1.0, 1.0, 1.0};
|
|
|
|
static GLboolean smooth = 1;
|
|
|
|
static void
|
|
Idle(void)
|
|
{
|
|
static double t0 = -1.;
|
|
double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;;
|
|
if (t0 < 0.0)
|
|
t0 = t;
|
|
dt = t - t0;
|
|
t0 = t;
|
|
LightPos[0] += Delta * dt;
|
|
if (LightPos[0]>15.0 || LightPos[0]<-15.0)
|
|
Delta = -Delta;
|
|
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void Display( void )
|
|
{
|
|
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
|
|
|
|
glLightfv(GL_LIGHT0, GL_POSITION, LightPos);
|
|
|
|
glPushMatrix();
|
|
glRotatef(90.0, 1.0, 0.0, 0.0);
|
|
|
|
if (Mode==0) {
|
|
/* Typical method: diffuse + specular + texture */
|
|
glEnable(GL_TEXTURE_2D);
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, White); /* enable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, White); /* enable specular */
|
|
#ifdef GL_VERSION_1_2
|
|
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
|
|
#endif
|
|
glCallList(Sphere);
|
|
}
|
|
else if (Mode==1) {
|
|
/* just specular highlight */
|
|
glDisable(GL_TEXTURE_2D);
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, Black); /* disable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, White); /* enable specular */
|
|
#ifdef GL_VERSION_1_2
|
|
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
|
|
#endif
|
|
glCallList(Sphere);
|
|
}
|
|
else if (Mode==2) {
|
|
/* diffuse textured */
|
|
glEnable(GL_TEXTURE_2D);
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, White); /* enable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, Black); /* disable specular */
|
|
#ifdef GL_VERSION_1_2
|
|
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
|
|
#endif
|
|
glCallList(Sphere);
|
|
}
|
|
else if (Mode==3) {
|
|
/* 2-pass: diffuse textured then add specular highlight*/
|
|
glEnable(GL_TEXTURE_2D);
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, White); /* enable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, Black); /* disable specular */
|
|
#ifdef GL_VERSION_1_2
|
|
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SINGLE_COLOR);
|
|
#endif
|
|
glCallList(Sphere);
|
|
/* specular highlight */
|
|
glDepthFunc(GL_EQUAL); /* redraw same pixels */
|
|
glDisable(GL_TEXTURE_2D);
|
|
glEnable(GL_BLEND); /* add */
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, Black); /* disable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, White); /* enable specular */
|
|
glCallList(Sphere);
|
|
glDepthFunc(GL_LESS);
|
|
glDisable(GL_BLEND);
|
|
}
|
|
else if (Mode==4) {
|
|
/* OpenGL 1.2's separate diffuse and specular color */
|
|
glEnable(GL_TEXTURE_2D);
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, White); /* enable diffuse */
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, White); /* enable specular */
|
|
#ifdef GL_VERSION_1_2
|
|
glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL, GL_SEPARATE_SPECULAR_COLOR);
|
|
#endif
|
|
glCallList(Sphere);
|
|
}
|
|
|
|
glPopMatrix();
|
|
|
|
glutSwapBuffers();
|
|
}
|
|
|
|
|
|
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( 0.0, 0.0, -12.0 );
|
|
}
|
|
|
|
|
|
static void Key( unsigned char key, int x, int y )
|
|
{
|
|
(void) x;
|
|
(void) y;
|
|
switch (key) {
|
|
case 27:
|
|
exit(0);
|
|
break;
|
|
case 's':
|
|
smooth = !smooth;
|
|
if (smooth)
|
|
glShadeModel(GL_SMOOTH);
|
|
else
|
|
glShadeModel(GL_FLAT);
|
|
break;
|
|
}
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void SpecialKey( int key, int x, int y )
|
|
{
|
|
(void) x;
|
|
(void) y;
|
|
switch (key) {
|
|
case GLUT_KEY_UP:
|
|
break;
|
|
case GLUT_KEY_DOWN:
|
|
break;
|
|
}
|
|
glutPostRedisplay();
|
|
}
|
|
|
|
|
|
static void Init( void )
|
|
{
|
|
int i, j;
|
|
GLubyte texImage[64][64][3];
|
|
|
|
glEnable(GL_LIGHTING);
|
|
glEnable(GL_LIGHT0);
|
|
glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, 0);
|
|
glLightModelfv(GL_LIGHT_MODEL_AMBIENT, Black);
|
|
|
|
glShadeModel(GL_SMOOTH);
|
|
|
|
glMaterialfv(GL_FRONT, GL_DIFFUSE, White);
|
|
glMaterialfv(GL_FRONT, GL_SPECULAR, White);
|
|
glMaterialf(GL_FRONT, GL_SHININESS, 20.0);
|
|
|
|
/* Actually, these are set again later */
|
|
glLightfv(GL_LIGHT0, GL_DIFFUSE, White);
|
|
glLightfv(GL_LIGHT0, GL_SPECULAR, White);
|
|
|
|
Quadric = gluNewQuadric();
|
|
gluQuadricTexture( Quadric, GL_TRUE );
|
|
|
|
Sphere= glGenLists(1);
|
|
glNewList( Sphere, GL_COMPILE );
|
|
gluSphere( Quadric, 1.0, 24, 24 );
|
|
glEndList();
|
|
|
|
glEnable(GL_DEPTH_TEST);
|
|
glEnable(GL_CULL_FACE);
|
|
|
|
for (i=0;i<64;i++) {
|
|
for (j=0;j<64;j++) {
|
|
int k = ((i>>3)&1) ^ ((j>>3)&1);
|
|
texImage[i][j][0] = 255*k;
|
|
texImage[i][j][1] = 255*(1-k);
|
|
texImage[i][j][2] = 0;
|
|
}
|
|
}
|
|
|
|
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
|
|
glTexImage2D( GL_TEXTURE_2D,
|
|
0,
|
|
3,
|
|
64, 64,
|
|
0,
|
|
GL_RGB, GL_UNSIGNED_BYTE,
|
|
texImage );
|
|
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
|
|
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
|
|
glEnable(GL_TEXTURE_2D);
|
|
|
|
glBlendFunc(GL_ONE, GL_ONE);
|
|
}
|
|
|
|
|
|
static void ModeMenu(int entry)
|
|
{
|
|
if (entry==99)
|
|
exit(0);
|
|
Mode = entry;
|
|
}
|
|
|
|
|
|
int main( int argc, char *argv[] )
|
|
{
|
|
|
|
glutInit( &argc, argv );
|
|
glutInitWindowPosition( 0, 0 );
|
|
glutInitWindowSize( 300, 300 );
|
|
|
|
glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
|
|
|
|
glutCreateWindow( "spectex" );
|
|
|
|
Init();
|
|
|
|
glutReshapeFunc( Reshape );
|
|
glutKeyboardFunc( Key );
|
|
glutSpecialFunc( SpecialKey );
|
|
glutDisplayFunc( Display );
|
|
glutIdleFunc( Idle );
|
|
|
|
glutCreateMenu( ModeMenu );
|
|
glutAddMenuEntry("1-pass lighting + texturing", 0);
|
|
glutAddMenuEntry("specular lighting", 1);
|
|
glutAddMenuEntry("diffuse lighting + texturing", 2);
|
|
glutAddMenuEntry("2-pass lighting + texturing", 3);
|
|
#ifdef GL_VERSION_1_2
|
|
glutAddMenuEntry("OpenGL 1.2 separate specular", 4);
|
|
#endif
|
|
glutAddMenuEntry("Quit", 99);
|
|
glutAttachMenu(GLUT_RIGHT_BUTTON);
|
|
|
|
glutMainLoop();
|
|
return 0;
|
|
}
|