7 replies to this topic

[assainator]

Hello all,

I'm working on a OpenGL project but I'm having troubles with the perspective. The meshes appear to be scaled up on the x-axis.
In the image below, you can see a sphere that is supposed to be, well, a sphere, round. Obviously it's not. What causes this behavior?



Thanks in advance.

[Brother Bob]

Likely an incorrect aspect ratio. That is, your projection assumes the width and the height of the window are the same, but in reality the window is wider, and so the image looks stretched.

[themean]

which opengl you use
if you use 2.1 may be i can help
i think your window is stretched and you dont calculate this

[SaTANO]

your projection matrix is not properly set for your rendering viewport

check glViewPort(x,y,width,height) for aspect ratio (you are probably not rendering 1:1)
than set/create projection matrix for correct values

[assainator]

I'm using OGL 2.0.

My code is:

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glViewport(0,0, Resolution.x, Resolution.y);
gluPerspective(90, (Resolution.x / Resolution.y), 1.0f, 5000.0f);
glMatrixMode(GL_MODELVIEW);

[mhagain]

Are resolution.x and resolution.y ints? If so you'll always* get an aspect of 1 when you divide them. Cast them to floats instead.

*: Unless height is greater than width, of course.

[assainator]

Are resolution.x and resolution.y ints? If so you'll always* get an aspect of 1 when you divide them. Cast them to floats instead.

*: Unless height is greater than width, of course.

Sometimes I just do not understand how I don't notice that kind of simple problems....

That, off course, fixed the problem.

[NickWiggill]

Haha, this just helped me out too. Thanks mhagain.