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Posted 23 September 2012 - 05:27 PM

First of all, I've never heard the term pre-vertex lighting so I assume you mixed it up somewhere with per-vertex lighting.

Second, you're overcomplicating matters by dragging in completely unrelated topics into the discussion, and I think you just have a completely wrong image of what the terms per-vertex and per-pixel lighting mean.

Here's a simple explanation:
Per-vertex and per-pixel lighting are both ways of evaluating a BRDF, mostly done in a shader. Per-vertex lighting evaluates your BRDF for each light for each vertex in your model, per-pixel lighting calculates the BRDF for each resulting pixel which makes up your model in your lighted image.
Per-vertex lighting is faster when the vertex density of your model is lower than the resulting pixel density but will generally give very low quality results for meshes with a low vertex density.
Per-pixel lighting will generally give better results than per-vertex lighting, but is more expensive to calculate in most of the cases, although this overhead is mostly negligible these days.

Techniques like sky lights, particle lights, atmospheric effects, etc. require you to make far tougher decisions than the decision of whether to choose per-vertex of per-pixel lighting, so it might be a good idea to read up on very basic lighting principle before you continue on to the advanced topics.

Posted 23 September 2012 - 05:27 PM

First of all, I've never heard the term pre-vertex lighting so I assume you mixed it up somewhere with per-vertex lighting.

Second, you're overcomplicating matters by dragging in completely unrelated topics into the discussion, and I think you just have a completely wrong image of what the terms per-vertex and per-pixel lighting mean.

Here's a simple explanation:
Per-vertex and per-pixel lighting are both ways of evaluating a BRDF, mostly done in a shader. Per-vertex lighting evaluates your BRDF for each light for each vertex in your model, per-pixel lighting calculates the BRDF for each resulting pixel which making up your model in your lighted image.
Per-vertex lighting is faster when the vertex density of your model is lower than the resulting pixel density but will generally give very low quality results for meshes with a low vertex density.
Per-pixel lighting will generally give better results than per-vertex lighting, but is more expensive to calculate in most of the cases, although this overhead is mostly negligible these days.

Techniques like sky lights, particle lights, atmospheric effects, etc. require you to make far tougher decisions than the decision of whether to choose per-vertex of per-pixel lighting, so it might be a good idea to read up on very basic lighting principle before you continue on to the advanced topics.

Posted 23 September 2012 - 05:26 PM

First of all, I've never heard the term pre-vertex lighting so I assume you mixed it up somewhere with per-vertex lighting.

Second, you're overcomplicating matters by dragging in completely unrelated topics into the matter, and I think you just have a completely wrong image of what the terms per-vertex and per-pixel lighting mean.

Here's a simple explanation:
Per-vertex and per-pixel lighting are both ways of evaluating a BRDF, mostly done in a shader. Per-vertex lighting evaluates your BRDF for each light for each vertex in your model, per-pixel lighting calculates the BRDF for each resulting pixel which making up your model in your lighted image.
Per-vertex lighting is faster when the vertex density of your model is lower than the resulting pixel density but will generally give very low quality results for meshes with a low vertex density.
Per-pixel lighting will generally give better results than per-vertex lighting, but is more expensive to calculate in most of the cases, although this overhead is mostly negligible these days.

Techniques like sky lights, particle lights, atmospheric effects, etc. require you to make far tougher decisions than the decision of whether to choose per-vertex of per-pixel lighting, so it might be a good idea to read up on very basic lighting principle before you continue on to the advanced topics.

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