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render unit sphere 2D, OpenGL

Hey people, I need help rendering a unit sphere to a 2d img. by using the setpixel f'n. It is a 256 x 256.

This below only helps by covering all pixels and shading it white...

for (int x=0; x < 256; x++) {
            for (int y = 0; y < 256; y++) {
              int Px = ((x/128) - 1);
              int Py = ((y/128) - 1);
              int Pz = sqrt(Px*Px);
       if (sqrt(Px*Px + Py*Py) < 1)
                  img.setPixel(x, y, Pixel(1.0, 1.0, 1.0));

            }

      }

I also have to do lighting to shade this to make it look 3D..
Any help will be greatly appreciated! Thanks!

jose_juan

Hi MANNYWOOD,

to simulate 2D render use a glOrtho proyection matrix, in any case, you must use 3D real objects to compund your scene.

Before scene are rendered then get all viewport pixels with glReadPixels.

I think you don't need a realtime execution, in other case, (this way not is bad but) better (and complex) methods are available.

Do you need a explained example?

Good luck!

MANNYWOOD

ASKER

I'm not too sure still...
The form/ skeleton is already given with the projection, viewing and drawing of the matrix.
I guess when I mean the below only helps by covering all pixels and shading it white, that is the top left box in openGL which has a 256x256 setting and also allows mouse controls to cover pixels in the area. I guess representing a circle really isn't that easy in openGL.

An explained example will defenitley help!, that is.. if you don't mind.
Thanks again jose_juan!

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jose_juan

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MANNYWOOD

ASKER

Thanks~ Hopefully I could understand this.