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010.c
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010.c
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#include "screencasts.h"
/* Poor man's approximation of PI */
#define PI 3.1415926535898
/* Macro for sin & cos in degrees */
#define Cos(th) cos(PI/180*(th))
#define Sin(th) sin(PI/180*(th))
/* D degrees of rotation */
#define DEF_D 5
/* Globals */
double dim=5.0; /* dimension of orthogonal box */
char *windowName = "OpenGL screenscasts 10: Push and Pop Matrix and complex objects";
int windowWidth=500;
int windowHeight=450;
/* Various global state */
int toggleAxes = 1; /* toggle axes on and off */
int toggleValues = 1; /* toggle values on and off */
int toggleMode = 0; /* projection mode */
int th = 340; /* azimuth of view angle */
int ph = 30; /* elevation of view angle */
int fov = 55; /* field of view for perspective */
int asp = 1; /* aspect ratio */
/* Cube vertices */
GLfloat vertA[3] = { 0.5, 0.5, 0.5};
GLfloat vertB[3] = {-0.5, 0.5, 0.5};
GLfloat vertC[3] = {-0.5,-0.5, 0.5};
GLfloat vertD[3] = { 0.5,-0.5, 0.5};
GLfloat vertE[3] = { 0.5, 0.5,-0.5};
GLfloat vertF[3] = {-0.5, 0.5,-0.5};
GLfloat vertG[3] = {-0.5,-0.5,-0.5};
GLfloat vertH[3] = { 0.5,-0.5,-0.5};
/*
* project()
* ------
* Sets the projection
*/
void project()
{
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (toggleMode) {
/* perspective */
gluPerspective(fov,asp,dim/4,4*dim);
}
else {
/* orthogonal projection*/
glOrtho(-dim*asp,+dim*asp, -dim,+dim, -dim,+dim);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
/*
* setEye()
* ------
* Set the eye position
*/
void setEye()
{
if (toggleMode) {
double Ex = -2*dim*Sin(th)*Cos(ph);
double Ey = +2*dim *Sin(ph);
double Ez = +2*dim*Cos(th)*Cos(ph);
/* camera/eye position, aim of camera lens, up-vector */
gluLookAt(Ex,Ey,Ez , 0,0,0 , 0,Cos(ph),0);
}
/* Orthogonal - set world orientation */
else {
glRotatef(ph,1,0,0);
glRotatef(th,0,1,0);
}
}
/*
* drawAxes()
* ------
* Draw the axes
*/
void drawAxes()
{
if (toggleAxes) {
/* Length of axes */
double len = 2.0;
glColor3f(1.0,1.0,1.0);
glBegin(GL_LINES);
glVertex3d(0,0,0);
glVertex3d(len,0,0);
glVertex3d(0,0,0);
glVertex3d(0,len,0);
glVertex3d(0,0,0);
glVertex3d(0,0,len);
glEnd();
/* Label axes */
glRasterPos3d(len,0,0);
print("X");
glRasterPos3d(0,len,0);
print("Y");
glRasterPos3d(0,0,len);
print("Z");
}
}
/*
* drawValues()
* ------
* Draw the values in the lower left corner
*/
void drawValues()
{
if (toggleValues) {
glColor3f(0.8,0.8,0.8);
printAt(5,5,"View Angle (th, ph) =(%d, %d)", th,ph);
printAt(5,25,"Projection mode =(%s)", toggleMode?"Perspective":"Orthogonal");
}
}
/*
* cube
* ------
* Draw a cube
* at (x,y,z)
* dimensions (dx,dy,dz)
* rotated th about the y axis
*/
void cube(double x,double y,double z,
double dx,double dy,double dz,
double th)
{
glPushMatrix();
/* Transform cube */
glTranslated(x,y,z);
glRotated(th,0,1,0);
glScaled(dx,dy,dz);
/* Cube */
glBegin(GL_QUADS);
/* front => ABCD yellow */
glColor3f(1.0,1.0,0.0);
glVertex3fv(vertA);
glVertex3fv(vertB);
glVertex3fv(vertC);
glVertex3fv(vertD);
/* back => FEHG red */
glColor3f(1.0,0.0,0.0);
glVertex3fv(vertF);
glVertex3fv(vertE);
glVertex3fv(vertH);
glVertex3fv(vertG);
/* right => EADH green */
glColor3f(0.0,1.0,0.0);
glVertex3fv(vertE);
glVertex3fv(vertA);
glVertex3fv(vertD);
glVertex3fv(vertH);
/* left => BFGC blue */
glColor3f(0.0,0.0,1.0);
glVertex3fv(vertB);
glVertex3fv(vertF);
glVertex3fv(vertG);
glVertex3fv(vertC);
/* top => EFBA turquoise */
glColor3f(0.0,1.0,1.0);
glVertex3fv(vertE);
glVertex3fv(vertF);
glVertex3fv(vertB);
glVertex3fv(vertA);
/* bottom => DCGH pink */
glColor3f(1.0,0.0,1.0);
glVertex3fv(vertD);
glVertex3fv(vertC);
glVertex3fv(vertG);
glVertex3fv(vertH);
glEnd();
glPopMatrix();
}
/*
* cone
* ------
* Draws a cone
* at (x,y,z)
* with radius r and height h
* with 360/deg sides
*/
void cone(double x,double y,double z,
double r,double h,int deg)
{
int k;
glPushMatrix();
/* Transformation */
glTranslated(x,y,z);
glScaled(r,h,r);
glRotated(-90,1,0,0);
/* sides */
glBegin(GL_TRIANGLES);
for (k=0;k<=360;k+=deg){
glColor3f(0.0,0.0,1.0);
glVertex3f(0,0,1);
glColor3f(0.0,1.0,1.0);
glVertex3f(Cos(k),Sin(k),0);
glColor3f(1.0,0.0,1.0);
glVertex3f(Cos(k+deg),Sin(k+deg),0);
}
glEnd();
/* bottom circle */
/* rotate back */
glRotated(90,1,0,0);
glBegin(GL_TRIANGLES);
glColor3f(1.0,1.0,0.0);
for (k=0;k<=360;k+=deg) {
glVertex3f(0,0,0);
glVertex3f(Cos(k),0,Sin(k));
glVertex3f(Cos(k+deg),0,Sin(k+deg));
}
glEnd();
glPopMatrix();
}
/*
* spike
* ------
* Draw a spike
* at (x, y, z)
* radius r, height h, with 360/deg sides
* rotated ox around the x axis
* rotated oy around the y axis
* rotated oz around the z axis
*/
void spike(double x, double y, double z,
double r,double h,int deg,
double ox,double oy,double oz)
{
glPushMatrix();
glRotated(oz,0,0,1);
glRotated(oy,0,1,0);
glRotated(ox,1,0,0);
cone(x,y,z, r,h,deg);
glPopMatrix();
}
/*
* towers
* ------
* Draw a tower
* at (x,y,z)
* dimensions (dx,dy,dz)
* rotated th about the y axis
*/
void tower(double x,double y,double z,
double dx,double dy,double dz,
double th)
{
glPushMatrix();
/* Transformation */
glTranslated(x,y,z);
glRotated(th,0,1,0);
glScaled(dx,dy,dz);
cube(0,1.5,0, 1,3,1, 0);
cube(0,3.5,0, 2,1,2, 45);
spike(0,1,-3.5, 0.5,1, 90, 90,0,0);
spike(0,1,3.5, 0.5,1, 90, -90,0,0);
spike(-3.5,1,0, 0.5,1, 90, 0,0,-90);
spike(3.5,1,0, 0.5,1, 90, 0,0,90);
glPopMatrix();
}
/*
* display()
* ------
* Display the scene
*/
void display()
{
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glEnable(GL_DEPTH_TEST);
glLoadIdentity();
/* setup functions */
setEye();
/* draw */
drawAxes();
drawValues();
/* magic here */
/*
cube(1,0,1, 1,1,1, 0);
cube(-1,0,1, 1,1,1, 0);
cone(0,1,0, 1,1,DEF_D);
cone(0,-1,0, 1,1,90);
*/
/* a 'tower' */
/*
cube(0,1.5,0, 1,3,1, 0);
cube(0,3.5,0, 2,1,2, 45);
spike(0,1,-3.5, 0.5,1, 90, 90,0,0);
spike(0,1,3.5, 0.5,1, 90, -90,0,0);
spike(-3.5,1,0, 0.5,1, 90, 0,0,-90);
spike(3.5,1,0, 0.5,1, 90, 0,0,90);
*/
tower(0,0,0, 1,1,1, 0);
tower(4,0,0, 1,1,1.5, 30);
glFlush();
glutSwapBuffers();
}
/*
* reshape()
* ------
* GLUT calls this routine when the window is resized
*/
void reshape(int width,int height)
{
asp = (height>0) ? (double)width/height : 1;
glViewport(0,0, width,height);
project();
}
/*
* windowKey()
* ------
* GLUT calls this routine when a non-special key is pressed
*/
void windowKey(unsigned char key,int x,int y)
{
/* Exit on ESC */
if (key == 27) exit(0);
else if (key == 'a' || key == 'A') toggleAxes = 1-toggleAxes;
else if (key == 'v' || key == 'V') toggleValues = 1-toggleValues;
else if (key == 'm' || key == 'M') toggleMode = 1-toggleMode;
/* Change field of view angle */
else if (key == '-' && key>1) fov--;
else if (key == '+' && key<179) fov++;
/* Change dimensions */
else if (key == 'D') dim += 0.1;
else if (key == 'd' && dim>1) dim -= 0.1;
project();
glutPostRedisplay();
}
/*
* windowSpecial()
* ------
* GLUT calls this routine when an arrow key is pressed
*/
void windowSpecial(int key,int x,int y)
{
/* Right arrow key - increase azimuth by 5 degrees */
if (key == GLUT_KEY_RIGHT) th += 5;
/* Left arrow key - decrease azimuth by 5 degrees */
else if (key == GLUT_KEY_LEFT) th -= 5;
/* Up arrow key - increase elevation by 5 degrees */
else if (key == GLUT_KEY_UP) ph += 5;
/* Down arrow key - decrease elevation by 5 degrees */
else if (key == GLUT_KEY_DOWN) ph -= 5;
/* Keep angles to +/-360 degrees */
th %= 360;
ph %= 360;
project();
glutPostRedisplay();
}
/*
* windowMenu
* ------
* Window menu is the same as the keyboard clicks
*/
void windowMenu(int value)
{
windowKey((unsigned char)value, 0, 0);
}
/*
* main()
* ----
* Start up GLUT and tell it what to do
*/
int main(int argc,char* argv[])
{
glutInit(&argc,argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(windowWidth,windowHeight);
glutCreateWindow(windowName);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(windowKey);
glutSpecialFunc(windowSpecial);
glutCreateMenu(windowMenu);
glutAddMenuEntry("Toggle Axes [a]",'a');
glutAddMenuEntry("Toggle Values [v]",'v');
glutAddMenuEntry("Toggle Mode [m]",'m');
glutAttachMenu(GLUT_RIGHT_BUTTON);
glutMainLoop();
return 0;
}