:: Per-Vertex LIghting ::
April 12, 2001 02:05 AM
Hi,
What is Per-Vertex Lighting ?
Please tell me all about it!
-Thx
171
April 12, 2001 02:53 AM
quote: Original post by Crash_Kid
Hi,
What is Per-Vertex Lighting ?
Please tell me all about it!
-Thx
Also called smooth shading, this involves calculating light values at each vertex of a polygon and interpolating between them when rasterizing the polygon to provide output colors.
122
April 12, 2001 02:58 AM
hi,
from an nvidia''s white paper www.nvidia.com/Pages.nsf/Lookup/Nsr2/$file/Nsr.pdf
"Vertex Lighting
Vertex lighting, an alternative method to light maps, computes lighting values on-the-fly for each
polygon in a scene. All real-time 3D graphics are composed of triangular polygons that consist of three
vertices. Each vertex contains information about its position, color, lighting, texture, and other
parameters that, together, can be used to construct an image. Per-vertex lighting calculations
determine the level of light for every vertex of every object in a scene and then interpolate those
values across the face of each triangle to produce its color[...]Vertex lighting applies its effects at the triangle level, which is a much coarser-grained working
unit. As a result, unless a model consists of a large number of triangles, per-vertex lighting will result
in a faceted, coarse-grained appearance[...]Vertex lighting is a flexible, dynamic way of calculating light values for a 3D scene. Unlike light maps,
this scheme does not require artwork to be produced in advance for every possible lighting scenario.
And unlike light maps, it does not require multitexturing to produce sophisticated effects. But
unfortunately, vertex lighting is of limited use in some scenarios because its base unit is the triangle.
In situations where dense tessellation is undesirable, light maps provide higher quality light effects
because they are bit-mapped textures and provide pixel-level accuracy.
Developers have pushed the limits of both lighting schemes in an attempt to strike a difficult balance
between quality, flexibility, and performance. An ideal lighting technique would combine the
calculative, dynamic nature of vertex lighting with the pixel-level accuracy of light maps."
lunasol
from an nvidia''s white paper www.nvidia.com/Pages.nsf/Lookup/Nsr2/$file/Nsr.pdf
"Vertex Lighting
Vertex lighting, an alternative method to light maps, computes lighting values on-the-fly for each
polygon in a scene. All real-time 3D graphics are composed of triangular polygons that consist of three
vertices. Each vertex contains information about its position, color, lighting, texture, and other
parameters that, together, can be used to construct an image. Per-vertex lighting calculations
determine the level of light for every vertex of every object in a scene and then interpolate those
values across the face of each triangle to produce its color[...]Vertex lighting applies its effects at the triangle level, which is a much coarser-grained working
unit. As a result, unless a model consists of a large number of triangles, per-vertex lighting will result
in a faceted, coarse-grained appearance[...]Vertex lighting is a flexible, dynamic way of calculating light values for a 3D scene. Unlike light maps,
this scheme does not require artwork to be produced in advance for every possible lighting scenario.
And unlike light maps, it does not require multitexturing to produce sophisticated effects. But
unfortunately, vertex lighting is of limited use in some scenarios because its base unit is the triangle.
In situations where dense tessellation is undesirable, light maps provide higher quality light effects
because they are bit-mapped textures and provide pixel-level accuracy.
Developers have pushed the limits of both lighting schemes in an attempt to strike a difficult balance
between quality, flexibility, and performance. An ideal lighting technique would combine the
calculative, dynamic nature of vertex lighting with the pixel-level accuracy of light maps."
lunasol
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