Aspect Ratio Stretching in OpenGL -

i having trouble full screen mode. can set window 800x600, when full screen resolution, stretches. assume because of change in aspect ratio. how can fix this?

edit #1

here's screen shot of see happening.

left: 800x600

right: 1366x768

edit #2

my initgraphics function gets called every time re-size window (wm_size).

void initgraphics(int width, int height) {     float aspect = (float)width / (float)height;     glviewport(0, 0, width, height);     glenable(gl_texture_2d);     glenable(gl_blend); //enable alpha blending     glblendfunc(gl_src_alpha, gl_one_minus_src_alpha);     glclearcolor(0.0, 0.0, 0.0, 1.0);     glmatrixmode(gl_projection);     glloadidentity();     gluortho2d(0.0, width, height * aspect, 0.0);     glmatrixmode(gl_modelview); } 

solution: real problem ended being misusing gluortho2d function. instead of using this:

gluortho2d(0.0, width, height * aspect, 0.0); 

you needed switch correct form this:

gluortho2d(0.0, width, 0.0, height); 

the latter creates 2d orthographic projection, fills entire width , height of viewport, no stretching occurs.

original answer:

you need modify projection in order account new aspect ratio.

make sure first of set glviewport new window size. after viewport set need switch matrix mode projection call glmatrixmode , calculate new aspect ratio width / height , pass new aspect ratio gluperspective. can use straight glfrustum instead of gluperspective can find source gluperspective achieve same effect glfrustum.

something this:

    float aspectratio = width / height;     glmatrixmode(gl_projection_matrix);     glloadidentity();     gluperspective(fov, aspectratio, near, far);