Switching Between Orthographic and Perspective Views

OpenGL OpenGL: Basic Coding
1

I am trying to enable my program to switch between orthographic and perspective modes. Here’s my code:

void reshape(int w, int h){
	cout << "
In Reshape";

	if(h == 0)
		h = 1;

	float ratio = 1.0* (float)w / (float)h;
	float ratio1 = 1.0* (float)h / (float)w;
	
	ww=w; wh=h;
	if(orthographic){
		cout << "
In Ortho";
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		
		// Set the viewport to be the entire window
		glViewport(0, 0, w, h);

		// Set the correct perspective.
		if(w<=h){
			glOrtho((-10), 4, ratio1*(-5), ratio1*9, 2, 20);
		}
		else{
			glOrtho(ratio*(-10), ratio*4, (-5), 9, 2, 20);
		}

		glMatrixMode(GL_MODELVIEW);
	}
	if(perspective){
		cout << "
In Persp";

		// Reset the coordinate system before modifying
		glMatrixMode(GL_PROJECTION);
		glLoadIdentity();
		
		// Set the viewport to be the entire window
		glViewport(0, 0, w, h);

		// Set the correct perspective.
		gluPerspective(90, ratio, 1, 30);
		glMatrixMode(GL_MODELVIEW);

	}

}

nothing happens when i call reshape and want the switches to be made. is there another way to do this?

2

do you then redraw the screen? Changing the projection matrix won’t suddenly change what has already been drawn; you have to repaint the screen to see any new effect.

cheers
John