GLUT02

GLUT02.cpp

#include <OpenGL/OpenGL.h>
#include <GLUT/GLUT.h>


void renderScene(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    
    glColor3f(1.0f, 0.0f, 0.0f);
    
    glRectf(-25.0f, 25.0f, 25.0f, -25.0f);
    
    
    glFlush();
}

void changeSize(GLsizei w, GLsizei h)
{
    GLfloat aspectRatio;
    
    if(h==0)
        h = 1;
    
    glViewport(0, 0, w, h);
    
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    
    aspectRatio = (GLfloat)w / (GLfloat)h;
    if(w <= h)
        glOrtho(-100, 100, -100/aspectRatio, 100/aspectRatio, 1.0, -1.0);
    else
        glOrtho(-100 * aspectRatio, 100*aspectRatio, -100.0, 100.0, 1.0, -1.0);
    
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

void setupRenderingContext(void)
{
    glClearColor(0.0, 0.0, 0.0, 1.0f);
}

int main(int argc, const char * argv[])
{
    glutInit(&argc, const_cast<char **>(argv));
    glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
    glutCreateWindow("Hello GLUT");
    glutReshapeFunc(changeSize);
    glutDisplayFunc(renderScene);
    setupRenderingContext();
    glutMainLoop();
    return 0;
}