bezier.cpp

/* Libraries */

#ifdef __APPLE__
#include <GLUT/glut.h>
#include <OpenGL/gl.h>
#include <OpenGL/glu.h>
#else
#include <GL/glut.h>
#include <GL/glu.h>
#include <GL/gl.h>
#endif
#include <iostream>
#include <math.h>

#define WINDOW_WIDTH 1400
#define WINDOW_HEIGHT 800

double t = 0;
int x, y, beizer_timer=0;
int p0[2], p1[2], p2[2], p3[2];
bool movement_reverse = false;


int* bezier(float t, int* p0,int* p1,int* p2,int* p3) {
    int res[2];
    res[0]=pow((1-t),3)*p0[0]+3*t*pow((1-t),2)*p1[0]+3*pow(t,2)*(1-t)*p2[0]+pow(t,3)*p3[0];
    res[1]=pow((1-t),3)*p0[1]+3*t*pow((1-t),2)*p1[1]+3*pow(t,2)*(1-t)*p2[1]+pow(t,3)*p3[1];
    return res;
}


void display() {
    start:
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    
    glColor3f(1.0, 0.0, 0.0);
    glBegin(GL_POLYGON);
        glVertex2f(x, y);
        glVertex2f(x + 100, y);
        glVertex2f(x + 100, y + 100);
        glVertex2f(x, y + 100);
    glEnd();

    
    glFlush();
    glutSwapBuffers();
    glutPostRedisplay();
}

void timer(int value) {

    beizer_timer += 30;
    if(beizer_timer > 100) {
        beizer_timer = 0;
        t += (0.01);
    }
    if(t > 1) {
        p1[0] += 50;
        p1[1] += 50;
        
        p2[0] += 50;
        p2[1] += 50;

        t = 0;
    }

    int *res = bezier(t, p0, p1, p2, p3);
    
    x = res[0];
    y = res[1];
    // std::cout<<"X: "<<x<<"Y: "<<y<<"T: "<<t<<"\n";
    glutTimerFunc(0, timer, 0);
    glutPostRedisplay();

}

// -----------------------------------
//               Main
// -----------------------------------
int main(int argc, char** argv) {
    /* Initializers */
    srand((unsigned)time(0));
    glutInit(&argc, argv);
    glutInitWindowSize(WINDOW_WIDTH, WINDOW_HEIGHT);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowPosition(50, 50);
    glutCreateWindow("Kayid - Space Invaders");
    
    t = 0;

    p0[0]=WINDOW_WIDTH / 4;
    p0[1]=WINDOW_WIDTH / 4 + 100;
    
    p1[0]=WINDOW_WIDTH / 4;
    p1[1]=WINDOW_WIDTH / 4 + 400;
    
    p2[0]=WINDOW_WIDTH / 4 + 800;
    p2[1]=WINDOW_WIDTH / 4 + 400;
    
    p3[0]=WINDOW_WIDTH / 4 + 800;
    p3[1]=WINDOW_WIDTH / 4 + 100;

    x = WINDOW_WIDTH / 2;
    y = WINDOW_HEIGHT / 2;
    
    /* Callbacks */
    glutDisplayFunc(display);
    glutTimerFunc(0, timer, 0);
    
    glClearColor(1, 1, 1, 0);
    gluOrtho2D(0, WINDOW_WIDTH, 0, WINDOW_HEIGHT);
    
    /* Main loop */
    glutMainLoop();
    return 0;
}