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POHow do I set up my openGL blending so that I can draw on only the opaque areas on a CCRenderTexture using a CCSprite that has some transparency?
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copied!<p>I'm having trouble drawing to a CCRenderTexture with a texture that includes transparency due to the blending that I've used.</p> <p>The sprite that I am drawing with has a blending function of:</p> <p><code>glBlendFunc(GL_DST_ALPHA, GL_ONE_MINUS_DST_ALPHA)</code>.</p> <p>The render texture that it is drawing to has the blending function:</p> <p><code>glBlendFuncSeparate(GL_DST_COLOR, GL_ONE_MINUS_SRC_ALPHA, GL_SRC_COLOR, GL_ONE_MINUS_SRC_ALPHA)</code>.</p> <p>The render texture is set up with it being mostly transparent with some completely opaque areas on it. The above blend functions allow me to draw with a completely solid sprite on the solid areas while it not drawing on the transparent areas.</p> <p>Trouble arises when I try to change the sprite that I draw with to include some transparency. It tends to "erase" the opaque areas on the render texture. Ideally I would like the transparent areas on the sprite that I draw with to have no effect. I was wondering if an openGL blending guru was able to give me some guidance?</p> <p>To clarify, the final effect that I am trying to achieve is to be able draw a sprite that includes some transparent areas to my render texture. The transparent areas of the sprite should not draw to my render texture. The opaque areas of the sprite should only draw to the render texture if they are over an opaque area on the render texture.</p>

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