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#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <GL/glut.h>
#ifndef __sgi
/* Most math.h's do not define float versions of math functions. */
#define floorf(x) ((float)floor((x)))
#endif
static float transx = 1.0, transy, rotx, roty;
static int ox = -1, oy = -1;
static int mot = 0;
#define PAN 1
#define ROT 2
void
pan(const int x, const int y) {
transx += (x-ox)/5.;
transy -= (y-oy)/5.;
ox = x; oy = y;
glutPostRedisplay();
}
void
rotate(const int x, const int y) {
rotx += x-ox;
if (rotx > 360.) rotx -= 360.;
else if (rotx < -360.) rotx += 360.;
roty += y-oy;
if (roty > 360.) roty -= 360.;
else if (roty < -360.) roty += 360.;
ox = x; oy = y;
glutPostRedisplay();
}
void
motion(int x, int y) {
if (mot == PAN) pan(x, y);
else if (mot == ROT) rotate(x,y);
}
void
mouse(int button, int state, int x, int y) {
if(state == GLUT_DOWN) {
switch(button) {
case GLUT_LEFT_BUTTON:
mot = PAN;
motion(ox = x, oy = y);
break;
case GLUT_MIDDLE_BUTTON:
mot = ROT;
motion(ox = x, oy = y);
break;
case GLUT_RIGHT_BUTTON:
break;
}
} else if (state == GLUT_UP) {
mot = 0;
}
}
#define stripeImageWidth 32
GLubyte stripeImage[4*stripeImageWidth];
void makeStripeImage(void) {
int j;
for (j = 0; j < stripeImageWidth; j++) {
stripeImage[4*j] = (GLubyte) ((j<=4) ? 255 : 0);
stripeImage[4*j+1] = (GLubyte) ((j>4) ? 255 : 0);
stripeImage[4*j+2] = (GLubyte) 0;
stripeImage[4*j+3] = (GLubyte) 255;
}
}
void
hsv_to_rgb(float h,float s,float v,float *r,float *g,float *b)
{
int i;
float f, p, q, t;
h *= 360.0;
if (s==0) {
*r = v;
*g = v;
*b = v;
} else {
if (h==360)
h = 0;
h /= 60;
i = floorf(h);
f = h - i;
p = v*(1.0-s);
q = v*(1.0-(s*f));
t = v*(1.0-(s*(1.0-f)));
switch (i) {
case 0 :
*r = v;
*g = t;
*b = p;
break;
case 1 :
*r = q;
*g = v;
*b = p;
break;
case 2 :
*r = p;
*g = v;
*b = t;
break;
case 3 :
*r = p;
*g = q;
*b = v;
break;
case 4 :
*r = t;
*g = p;
*b = v;
break;
case 5 :
*r = v;
*g = p;
*b = q;
break;
}
}
}
GLubyte rainbow[4*stripeImageWidth];
void makeRainbow(void) {
int j;
for (j = 0; j < stripeImageWidth; j++) {
float r, g, b;
hsv_to_rgb((float)j/(stripeImageWidth-1.f), 1.0, 1.0, &r, &g, &b);
rainbow[4*j] = r*255;
rainbow[4*j+1] = g*255;
rainbow[4*j+2] = b*255;
rainbow[4*j+3] = (GLubyte) 255;
}
}
/* planes for texture coordinate generation */
static GLfloat xequalzero[] = {1.0, 0.0, 0.0, 0.0};
static GLfloat slanted[] = {1.0, 1.0, 1.0, 0.0};
static GLfloat *currentCoeff;
static GLenum currentPlane;
static GLint currentGenMode;
void init(void) {
glClearColor (0.0, 0.0, 0.0, 0.0);
glEnable(GL_DEPTH_TEST);
glShadeModel(GL_SMOOTH);
makeStripeImage();
makeRainbow();
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage1D(GL_TEXTURE_1D, 0, 4, stripeImageWidth, 0,
GL_RGBA, GL_UNSIGNED_BYTE, stripeImage);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
currentCoeff = xequalzero;
currentGenMode = GL_OBJECT_LINEAR;
currentPlane = GL_OBJECT_PLANE;
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
glTexGenfv(GL_S, currentPlane, currentCoeff);
glEnable(GL_TEXTURE_GEN_S);
glEnable(GL_TEXTURE_1D);
glEnable(GL_CULL_FACE);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_AUTO_NORMAL);
glEnable(GL_NORMALIZE);
glFrontFace(GL_CW);
glCullFace(GL_BACK);
glMaterialf (GL_FRONT, GL_SHININESS, 64.0);
}
void tfunc(void) {
static int state;
if (state ^= 1) {
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage1D(GL_TEXTURE_1D, 0, 4, stripeImageWidth, 0,
GL_RGBA, GL_UNSIGNED_BYTE, rainbow);
} else {
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexImage1D(GL_TEXTURE_1D, 0, 4, stripeImageWidth, 0,
GL_RGBA, GL_UNSIGNED_BYTE, stripeImage);
}
glutPostRedisplay();
}
void display(void) {
#if 0
static GLUquadricObj *q = NULL;
#endif
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPushMatrix();
glTranslatef(0., 0., transx);
glRotatef(rotx, 1.0, 0.0, 0.0);
glRotatef(45.0, 0.0, 0.0, 1.0);
glutSolidTeapot(2.0);
#if 0
if (!q) q = gluNewQuadric();
gluQuadricTexture(q, GL_TRUE);
gluCylinder(q, 1.0, 2.0, 3.0, 10, 10);
#endif
glPopMatrix();
glutSwapBuffers();
}
void reshape(int w, int h) {
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w <= h)
glOrtho (-3.5, 3.5, -3.5*(GLfloat)h/(GLfloat)w,
3.5*(GLfloat)h/(GLfloat)w, -3.5, 3.5);
else
glOrtho (-3.5*(GLfloat)w/(GLfloat)h,
3.5*(GLfloat)w/(GLfloat)h, -3.5, 3.5, -3.5, 3.5);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
/*ARGSUSED1*/
void keyboard (unsigned char key, int x, int y) {
switch (key) {
case 'e':
case 'E':
currentGenMode = GL_EYE_LINEAR;
currentPlane = GL_EYE_PLANE;
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
glTexGenfv(GL_S, currentPlane, currentCoeff);
glutPostRedisplay();
break;
case 'o':
case 'O':
currentGenMode = GL_OBJECT_LINEAR;
currentPlane = GL_OBJECT_PLANE;
glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, currentGenMode);
glTexGenfv(GL_S, currentPlane, currentCoeff);
glutPostRedisplay();
break;
case 's':
case 'S':
currentCoeff = slanted;
glTexGenfv(GL_S, currentPlane, currentCoeff);
glutPostRedisplay();
break;
case 'x':
case 'X':
currentCoeff = xequalzero;
glTexGenfv(GL_S, currentPlane, currentCoeff);
glutPostRedisplay();
break;
case 't': tfunc(); break;
case 27:
exit(0);
break;
default:
break;
}
}
int main(int argc, char*argv[]) {
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(256, 256);
glutInitWindowPosition(100, 100);
glutInit(&argc, argv);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMouseFunc(mouse);
glutMotionFunc(motion);
glutMainLoop();
return 0;
}
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