Dear All, I'm just picking up osgShadow, and have a couple of questions that I would appreciate some advice on. The intention is to use one of the ShadowMap type methods.
Case1 : Shadow casters already have expensive fragment shaders In the case where the objects that are casting shadows have expensive fragment shaders, I would prefer to turn these shaders off so that we just get a quick depth only pass. Fortunately my expensive shaders sit above the object's scenegraph, and so I can envisage an approach in which my unshaded object has two parent nodes (say A and B), which are both children of the shadow node. A would have the castsShadow mask and a cheap shader, and B would have the receivesShadow mask and the expensive shader. Does this sound like an acceptable approach? I have read things about using uniforms passed into the shader to control whether it is operating or not, but the above seemed a little simpler. Does this already happen via the shadow camera's use of GL_DEPTH Case2 : Shadow receivers musn't be children of the shadow node. For good architectural reasons, I can not place one of my desired shadow receiving items underneath the shadow node. Hence I would like access to the shadow texture, so that it can bind it explicitly. Would allowing the ShadowTechnique classes to expose their RTT shadow texture so that something else can also bind it be a problem in general? At the moment its protected. Is this something worth submitting or should I just subclass/rewrite? Case3 : Multitextured shadow receivers I realise that multitextured items aren't really supported by the out-of-the-box shadow techniques, but at the moment the handling of the shadow texture units and "base" texture units seems a little clumsy, and difficult to extend. Does anybody else have any experience of using shadows with objects that are already multitextured (e.g. diffuse and normal mapped)? It looks to me that if you have any other shaders knocking around your scenegraph, you need to subclass ShadowTechnique to support your usage model. Is that what people have done in the past? Thanks, David
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