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Structure

OpenGL Help recreating an effect on restricted hardware (img inc)

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Structure    240
Hi, Im interested in peoples opinions on if this effect could be recreated efficiently using fixed function hardware with no stencil buffer, ie opengl|es 1.0 (with hardware restrictions) There’s a video here to better see the effect. I can do toon shading but this is slightly different as it relies more on shadowing to create depth, and also edge drawing (I think). Would it be possible to pre-bake the background as I would not need dynamic lighting? Any ideas appreciated.

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Nik02    4348
The cartoon shading can be achieved by using a simple per-vertex logic - compute the dot product of the vertex normal and the light direction clamped to 0...1 to a texture coordinate, and use it to sample a 2-color texture with the color bands in it. This can be done in your app or in a vertex shader, depending on the hardware capabilities. Also, edge drawing can be done similarly by using the eye direction instead of the light direction when performing the dot product.

You could pre-bake the background shadows, if they are formed from static geometry. However, dynamic shadows are usually difficult on a restricted hardware. Does the OGL ES 1.0 support render target textures? You could render the shadow caster silhouettes to a texture from the light's point of view and project that texture to the shadow receivers. Note that this technique could also be used in pre-processing if the quality is good enough for your purpose.

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