I am trying to create a car game with along with obstacles. I want to add collision so every time my object hits one of the obstacles, obstacle changes color and we know there has been a collision. I also want there to be a collision around my screen so that my object can not leave the view port?
--void 'draw car' is my movable object
#include "include\freeglut.h" // OpenGL toolkit - in the local shared folder
#include <cmath>
#include <iostream>
//set up some constants
#define X_CENTRE 0.0 /* centre point of square */
#define Y_CENTRE 0.0
#define LENGTH 5.0 /* lengths of sides of square */
//forward declaration - best in the header
void drawStar(GLfloat radius, GLfloat x, GLfloat y);
void drawSquare(GLfloat length, GLfloat x, GLfloat y);
void drawRect(GLfloat lengthX, GLfloat lengthY, GLfloat x, GLfloat y);
void drawCar(GLfloat length, GLfloat x, GLfloat y);
GLfloat red = 1.0, green = 1.0, blue = 1.0;
GLint xmove = -12.0, ymove = -12.5, zmove = 0.0;
/* reshape callback function
executed when window is moved or resized. This function should be used in Tutorial 1 */
void reshape(int width, int height)
{
GLfloat aspect = (GLfloat)width / (GLfloat)height;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION); // To operate on the Projection matrix
glLoadIdentity();
// glOrtho(-10.0, 10.0, -10.0, 10.0, -1.0, 1.0); //sets the x,y,z plane from -1 to 1
if (width <= height) //if aspect is less or equal to 1
glOrtho(-10.0, 10.0, -10.0/aspect, 10.0/aspect, -1.0, 1.0);
else // aspect is greater than 1
glOrtho(-10.0 * aspect, 10.0* aspect, -10.0 , 10.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
}
/* display callback function
called whenever contents of window need to be re-displayed */
//this is the all important drawing method - all drawing code goes in here
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT); /* clear window */
/*glColor3f(1.0, 1.0, 1.0); /* white drawing objects */
glColor3f(0.0, 0.0, 1.0); /* blue drawing objects */
/* define object to be drawn as a square polygon */
glColor3f(0.3, -3.0, 4.0);
drawSquare(2, -3, 8);
glColor3f(0.3, -1.0, 2.0);
drawSquare(2, -3, 8);
glColor3f(1.0, 0.0, 0.0);
drawSquare(2, -5, -6);
glColor3f(0.0, 1.0, 0.0);
drawSquare(2, 0.0, 0.0);
glColor3f(2.0, 3.0, 1.1);
drawSquare(2, 6.0, 0.0);
glColor3f(0.3, -1.0, 2.0);
drawSquare(2, -6, 5);
glColor3f(0.7, -1.0, 2.0);
drawSquare(2, 5, -5);
glColor3f(0.0, 0.0, 1.0);
drawSquare(2, 5, 8);
glColor3f(0.75, 0.5, 0.25);
drawCar(1,0,0);
glFlush(); /* execute drawing commands in buffer */
}
void drawCar(GLfloat length, GLfloat x, GLfloat y) {
glPushMatrix();
glTranslatef(xmove, ymove, zmove);
//glBegin(GL_TRIANGLES);
////specify the vertices (points in 3D space) of the shape - note that these are 2D points
//glVertex2f(X_CENTRE - LENGTH / 3, Y_CENTRE - LENGTH / 3);
//glVertex2f(X_CENTRE - LENGTH / 3, Y_CENTRE + LENGTH / 3);
//glVertex2f(X_CENTRE + LENGTH / 3, Y_CENTRE + LENGTH / 3);
//glVertex2f(X_CENTRE + LENGTH / 3, Y_CENTRE - LENGTH / 3);
//glEnd();
glRectf(3, 4, 6, 2);
glPopMatrix();
glFlush();
}
void keyInput(unsigned char key, int x, int y)
{
switch (key)
{
case 'w':
ymove++;
if (ymove >= 10) ymove = 3.0;
break;
case 's':
ymove--;
// if (ymove <= -5) ymove = 0.0;
break;
case 'd':
xmove++;
// if (xmove >= 5) xmove = 0.0;
break;
case 'a':
xmove--;
// if (xmove <= -5) xmove = 0.0;
break;
}
glutPostRedisplay();
}
void drawSquare(GLfloat length, GLfloat x, GLfloat y)
{
//x1,y1 is the top left-hand corner coordinate
GLfloat x1, y1, x2, y2, x3, y3, x4, y4;
//glColor3f(0.1, 1.0, 0.2);
x1 = x - length / 2;
y1 = y + length / 2;
x2 = x + length / 2;
y2 = y + length / 2;
x3 = x + length / 2;
y3 = y - length / 2;
x4 = x - length / 2;
y4 = y - length / 2;
glBegin(GL_POLYGON);
glVertex2f(x1, y1);
glVertex2f(x2, y2);
glVertex2f(x3, y3);
glVertex2f(x4, y4);
glEnd();
glFlush();
}
void drawRect(GLfloat lengthX, GLfloat lengthY, GLfloat x, GLfloat y)
{
//x1,y1 is the top left-hand corner coordinate
GLfloat x1, y1, x2, y2, x3, y3, x4, y4;
//This example is for a rectangle
x1 = x - lengthX / 2;
y1 = y + lengthY / 2;
x2 = x + lengthX / 2;
y2 = y + lengthY / 2;
x3 = x + lengthX / 2;
y3 = y - lengthY / 2;
x4 = x - lengthX / 2;
y4 = y - lengthY / 2;
glBegin(GL_POLYGON);
glVertex2f(x1, y1);
glVertex2f(x2, y2);
glVertex2f(x3, y3);
glVertex2f(x4, y4);
glEnd();
glFlush();
}
//Draws a 5 pointed star using lines
void drawStar(GLfloat radius, GLfloat x, GLfloat y)
{
//x1,y1 is the top coordinate
//glColor3f(0.0, 1.0, 1.0);
GLfloat x1, y1, x2, y2, x3, y3, x4, y4, x5, y5;
x1 = x;
y1 = y + radius;
x2 = x + 0.90 * radius;
y2 = y + 0.40 * radius;
x3 = x + 0.65 * radius;
y3 = y - 0.55 * radius;
x4 = x - 0.65 * radius;
y4 = y - 0.55 * radius;
x5 = x - 0.90 * radius;
y5 = y + 0.40 * radius;
glLineWidth(1.0);
glBegin(GL_LINES);
glVertex2f(x1, y1);
glVertex2f(x3, y3);
glVertex2f(x1, y1);
glVertex2f(x4, y4);
glVertex2f(x2, y2);
glVertex2f(x4, y4);
glVertex2f(x2, y2);
glVertex2f(x5, y5);
glVertex2f(x3, y3);
glVertex2f(x5, y5);
glEnd();
glFlush();
}
/* graphics initialisation */
void init(void)
{
glClearColor(0.0, 0.0, 0.0, 0.0); //Setting up the background color
}
int main(int argc, char** argv)
{
/* window management code ... */
/* initialises GLUT and processes any command line arguments */
glutInit(&argc, argv);
/* use single-buffered window and RGBA colour model */
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA);
/* window width = 400 pixels, height = 400 pixels */
/* window width = 640 pixels, height = 480 pixels for a 4:3 ascpect ratio */
/* window width = 1024 pixels, height = 576 pixels for a 16:9 ascpect ratio */
glutInitWindowSize(750, 750);
/* window upper left corner at (100, 100) */
glutInitWindowPosition(100, 100);
/* creates an OpenGL window with command argument in its title bar */
glutCreateWindow("Example 1");
glutKeyboardFunc(keyInput);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
Keep track of your window size (750, 750), and your orthographic projection multiplier (10.0), then you should be able to tell when a certain world space coordinate is at the edge of the screen from these two.