Intel® 815 Chipset: Graphics Controller PRM, Rev 1.0

R

13.12.GFXRENDERSTATE_MAP_COLOR_BLEND_STAGES

The Rendering Engine supports three map color blend stages for the red, green, and blue channels. Any of these stages may perform an operation utilizing up to two texels from the Mapping Engine, the iterated face color, the iterated alpha and/or a constant color.

Figure 39. State Variable Relationships

Coordinate Sets

Map Information

Texels

Blending Stages

The following equations are supported by each blending stage.

Blend Equation

Description

 

 

Colorout = Arg1

Select Arg1

 

 

Colorout = Arg2

Select Arg2

 

 

Colorout = Arg1 * Arg2

Modulate

 

 

Colorout = Arg1 * Arg2 * 2

Modulate and Multiply by 2

 

 

Colorout = Arg1 * Arg2 * 4

Modulate and Multiply by 4

 

 

Colorout = Arg1 + Arg2

Add

 

 

Colorout = Arg1 - Arg2

Subtract

 

 

Colorout = Arg1 + Arg2 - 0.5

Add Signed (Excess 128)

 

 

Colorout = αIterated * Arg1 + (1 - αIterated) * Arg2

Linearly Blend using Iterated Alpha

 

 

Colorout = αFactor * Arg1 + (1 - αFactor) * Arg2

Linearly Blend using Alpha Factor

 

 

Colorout = αTexel0 * Arg1 + (1 - αTexel0) * Arg2

Linearly Blend using Texel0’s Alpha

 

 

Colorout = αTexel1 * Arg1 + (1 - αTexel1) * Arg2

Linearly Blend using Texel1’s Alpha

 

 

Colorout = ColorTexel0 * Arg1 + (1 - ColorTexel0) * Arg2

Linearly Blend using Texel0’s Color

 

 

Colorout = ColorTexel1 * Arg1 + (1 - ColorTexel1) * Arg2

Linearly Blend using Texel1’s Color

 

 

The settings for these stages are specified in the following instruction. When enable a stage for color operation, the corresponding alpha stage will also be enabled. The arguments and operation fields of the corresponding alpha stage must be programmed accordingly.

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Intel 815 manual Gfxrenderstatemapcolorblendstages, Blend Equation Description