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View Full Version : about projection ! could you tell me the difference....



release
11-27-2003, 10:24 PM
I projection vertex thange (x,y,z) to x [0,1] y [0,1] z [0,1] by my myselef like this
x = (x-xmin)/(xmax-xmin);
y = (y-ymin)/(ymax-ymin);
z = (z-zmin)/(zmax-zmin);

glMatrixMode(GL_PROJECTION)
glLoadIdentity();
gluPerspective(90,aspect,1,5)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity();
glTranslated(0,0,-3)
drawScene();

above code does work;
But i let gl projection (x,y,z) to x [0,1] y [0,1] z [0,1] code like this
glMatrixMode(GL_PROJECTION)
glLoadIdentity();
gluPerspective(90,aspect,1,5)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity();
glTranslated(-xMin,-yMin,-zMin)
glScaled(1.0f/(xMax-xMin),1.0f/(yMax-yMin),1.0f/(zMax-zMin)
glTranslated(0,0,-3)
drawScene();

it does not work as i like.Somebody help me!