Pelota Rebote

Código

#include <gl/glut.h>
#include <Math.h>
#define PI 3.14159265f

char title[] = "Rebote de una Pelota";
int windowWidth = 640;
int windowHeight = 480;
int windowPosX = 50;
int windowPosY = 50;

GLfloat ballRadius = 0.2f;
GLfloat xPos = 0.0f;
GLfloat yPos = 0.0f;
GLfloat xPosMax, xPosMin, yPosMax, yPosMin;
GLdouble xLeft, xRight, yBottom, yTop;
GLfloat xSpeed = 0.02f;
GLfloat ySpeed = 0.007f;
int refreshMillis = 10;

void initGL() {
glClearColor( 0.0, 0.0, 0.0, 0.0);
}

void display() {
glClear(GL_COLOR_BUFFER_BIT);

glLoadIdentity();
glTranslatef(xPos, yPos, 0.0f);

glBegin(GL_TRIANGLE_FAN);
glColor3f(1.0f, 0.0f, 1.0f);
glVertex2f(0.0f, 0.0f);
int numSegments = 100;
GLfloat angle;
for (int i = 0; i <= numSegments; i++) {
angle = i * 2.0f * PI / numSegments;
glVertex2f(cos(angle) * ballRadius, sin(angle) * ballRadius);
}
glEnd();

glutSwapBuffers();


xPos += xSpeed;
yPos += ySpeed;

if (xPos > xPosMax) {
xPos = xPosMax;
xSpeed = -xSpeed;
} else if (xPos < xPosMin) {
xPos = xPosMin;
xSpeed = -xSpeed;
}
if (yPos > yPosMax) {
yPos = yPosMax;
ySpeed = -ySpeed;
} else if (yPos < yPosMin) {
yPos = yPosMin;
ySpeed = -ySpeed;
}
}

void reshape(GLsizei weight, GLsizei height) {
if (height == 0) height = 1;
GLfloat aspect = (GLfloat)weight / height;

glViewport(0, 0, weight, height);


glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (weight <= height) {
xLeft = -1.0;
xRight = 1.0;
yBottom = -1.0 / aspect;
yTop = 1.0 / aspect;
} else {
xLeft = -1.0 * aspect;
xRight = 1.0 * aspect;
yBottom = -1.0;
yTop = 1.0;
}
gluOrtho2D(xLeft, xRight, yBottom, yTop);


yPosMin = yBottom + ballRadius;
yPosMax = yTop - ballRadius;


glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

void Timer(int value) {
glutPostRedisplay();
glutTimerFunc(refreshMillis, Timer, 0);
}

int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE);
glutInitWindowSize(windowWidth, windowHeight);
glutInitWindowPosition(windowPosX, windowPosY);
glutCreateWindow(title);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutTimerFunc(0, Timer, 0);
initGL();
glutMainLoop();
return 0;
}