texbeml (Pixel Shader)

Apply a fake bump environment-map transform with luminance correction. This is accomplished by modifying the texture address data of the destination register, using address perturbation data (du,dv), a 2-D bump environment matrix, and luminance.

Syntax

texbeml (Pixel Shader) dest, src

Registers

dest

Destination register.

src

Input source register.

Remarks

Pixel shader versions	1_1	1_2	1_3	1_4	2_0	2_x	2_sw	3_0	3_sw
texbeml	x	x	x

The red and green color data in the src register is interpreted as the perturbation data (du,dv). The blue color data in the src register is interpreted as the luminance data.

This instruction transforms the red and green components in the source register using the 2-D bump environment mapping matrix. The result is added to the texture coordinate set corresponding to the destination register number. A luminance correction is applied using the luminance value and the bias texture stage values. The result is used to sample the current texture stage.

This can be used for a variety of techniques based on address perturbation such as fake per-pixel environment mapping.

This operation always interprets du and dv as signed quantities. For versions 1_0 and 1_1, the Signed Scaling input modifier (_bx2) is not permitted on the input argument.

This instruction produces defined results when input textures contain mixed format data. For more information about surface formats, see D3DFORMAT.

// When using this instruction, texture registers must follow 
//   the following sequence.
// The texture assigned to stage tn contains the (du,dv) data.
// The texture assigned to stage t(m) is sampled.
tex     t(n)					
texbeml t(m),  t(n)      where m > n

This example shows the calculations done within the instruction.

// 1. New values for texture addresses (u',v') are calculated.
// 2. Sample the texture using (u',v').
// 3. Luminance correction is applied.

u' = TextureCoordinates(stage m)u + 
	D3DTSS_BUMPENVMAT00(stage m)*t(n)R +
	D3DTSS_BUMPENVMAT10(stage m)*t(n)G
	  
v' = TextureCoordinates(stage m)v + 
	D3DTSS_BUMPENVMAT01(stage m)*t(n)R +
	D3DTSS_BUMPENVMAT11(stage m)*t(n)G

t(m)RGBA = TextureSample(stage m) using (u',v') as coordinates.

t(m)RGBA = t(m)RGBA*
	[(t(n)B * D3DTSS_BUMPENVLSCALE(stage m)) + 
		D3DTSS_BUMPENVLOFFSET(stage m)]

Register data that has been read by a texbem or texbeml (Pixel Shader) instruction cannot be read later, except by another texbem or texbeml (Pixel Shader).

// This example demonstrates the validation error caused by 
//   t0 being reread.
ps_1_1
tex t0
texbem t1, t0
add r0, t1, t0

(Instruction Error) (Statement 4) Register data that has been read by 
texbem or texbeml instruction cannot be read by other instructions.

Examples

Here is an example shader with the texture maps identified and the texture stages identified.

ps_1_1
tex t0              ; define t0 to get a 2-tuple DuDv
texbeml t1, t0      ; compute (u',v')
                    ; apply luminance correction                    
                    ; sample t1 using (u',v')
mov r0, t1          ; output result

This example requires the following textures in the following texture stages.

Stage 0 is assigned a bump map with (du, dv) perturbation data.

Stage 1 is assigned a texture map with color data.

texbeml (Pixel Shader) sets the matrix data on the texture stage that is sampled.

This is different from the functionality of the fixed function pipeline where the perturbation data and the matrices occupy the same texture stage.

Instruction Information

Minimum operating systems	Windows 98