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Update comment in GrDrawState.h to reflect renaming changes and expansion of the scope of effects.

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Review URL: https://codereview.appspot.com/6777059

git-svn-id: http://skia.googlecode.com/svn/trunk@6138 2bbb7eff-a529-9590-31e7-b0007b416f81
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bsalomon@google.com 2012-10-26 13:41:59 +00:00
parent 070d354d51
commit 1322134a3a
1 changed files with 19 additions and 16 deletions
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35
src/gpu/GrDrawState.h
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@ -26,23 +26,26 @@ public:
SK_DECLARE_INST_COUNT(GrDrawState)
/**
* Number of effect stages. Each stage takes as input a color and
* 2D texture coordinates. The color input to the first enabled stage is the
* per-vertex color or the constant color (setColor/setAlpha) if there are
* no per-vertex colors. For subsequent stages the input color is the output
* color from the previous enabled stage. The output color of each stage is
* the input color modulated with the result of a texture lookup. Texture
* lookups are specified by a texture a sampler (setSamplerState). Texture
* coordinates for each stage come from the vertices based on a
* GrVertexLayout bitfield. The output fragment color is the output color of
* the last enabled stage. The presence or absence of texture coordinates
* for each stage in the vertex layout indicates whether a stage is enabled
* or not.
* Total number of effect stages. Each stage can host a GrEffect. A stage is enabled if it has a
* GrEffect. The effect produces an output color in the fragment shader. It's inputs are the
* output from the previous enabled stage and a position. The position is either derived from
* the interpolated vertex positions or explicit per-vertex coords, depending upon the
* GrVertexLayout used to draw.
*
* Stages 0 through GrPaint::kTotalStages-1 are reserved for setting up
* the draw (i.e., textures and filter masks). Stages GrPaint::kTotalStages
* through kNumStages-2 are earmarked for use by GrTextContext and
* GrPathRenderer-derived classes. kNumStages-1 is earmarked for clipping
* The stages are divided into two sets, color-computing and coverage-computing. The final color
* stage produces the final pixel color. The coverage-computing stages function exactly as the
* color-computing but the output of the final coverage stage is treated as a fractional pixel
* coverage rather than as input to the src/dst color blend step.
*
* The input color to the first enabled color-stage is either the constant color or interpolated
* per-vertex colors, depending upon GrVertexLayout. The input to the first coverage stage is
* either a constant coverage (usually full-coverage), interpolated per-vertex coverage, or
* edge-AA computed coverage. (This latter is going away as soon as it can be rewritten as a
* GrEffect).
*
* Stages 0 through GrPaint::kTotalStages-1 are reserved for stages copied from the client's
* GrPaint. Stages GrPaint::kTotalStages through kNumStages-2 are earmarked for use by
* GrTextContext and GrPathRenderer-derived classes. kNumStages-1 is earmarked for clipping
* by GrClipMaskManager.
*/
enum {