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OpenGL drawing filled disk

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hello.
I have created a little engine in 2d in opengl for qt.
I Would create a system for create a filled disk and a rectangle(for now) of different color ,positioned at the mouse x,y when i click.
The question is :
1)How i can create the disk? with the sine/cosine and a step angle and for the fill? but is better on the shader(GLSL) or on the cpu ?
2)i wish parametrize the color for ex.
If i create a vbo with the color attribute every time that the color must change i must change the vbo.
Is not better using a uniform var with the color and matrixes for the scale/translate/rotate for the entities?

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[quote name='giugio' timestamp='1350672851' post='4991864']
1)How i can create the disk? with the sine/cosine and a step angle and for the fill? but is better on the shader(GLSL) or on the cpu ?
[/quote]
As you will have about 100 vertices max, there is no reason to do it in GPU - calculate the positions (via sin/cos) on the CPU and store in VBO
[quote name='giugio' timestamp='1350672851' post='4991864']
2)i wish parametrize the color for ex.
If i create a vbo with the color attribute every time that the color must change i must change the vbo.
Is not better using a uniform var with the color and matrixes for the scale/translate/rotate for the entities?
[/quote]
You are already at correct path [img]http://public.gamedev.net//public/style_emoticons/default/wink.png[/img]

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