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Bobboau

useing alpha as a color

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I want to use the alpha chanel in a spec map as a modulator for an environment map. how shal this be done? this is what I have currently
bool set_stage_for_env_mapped(){
	if(current_render_state == ENV)return true;
	if(SPECMAP < 0){
	//	Error(LOCATION, "trying to set stage when there is no specmap");

		return false;
	}

//	D3DXMATRIX world;


	D3DXMATRIX world(
		Eye_matrix.vec.rvec.xyz.x, Eye_matrix.vec.rvec.xyz.y, Eye_matrix.vec.rvec.xyz.z, 0,
		Eye_matrix.vec.uvec.xyz.x, Eye_matrix.vec.uvec.xyz.y, Eye_matrix.vec.uvec.xyz.z, 0,
		Eye_matrix.vec.fvec.xyz.x, Eye_matrix.vec.fvec.xyz.y, Eye_matrix.vec.fvec.xyz.z, 0,
		0, 0, 0, 1);

	GlobalD3DVars::lpD3DDevice->SetTransform(D3DTS_TEXTURE1, &world);

	d3d_SetTextureStageState( 2, D3DTSS_RESULTARG, D3DTA_CURRENT);
	d3d_SetTextureStageState( 1, D3DTSS_RESULTARG, D3DTA_CURRENT);
	d3d_SetTextureStageState( 0, D3DTSS_RESULTARG, D3DTA_CURRENT);


//	d3d_SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_SPECULAR);

	d3d_SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE);
	d3d_SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_SELECTARG1);
//	d3d_SetTexture(0, SPECMAP);


	d3d_SetTexture(1, cube_map);
	d3d_SetTextureStageState( 1, D3DTSS_RESULTARG, D3DTA_CURRENT);
	d3d_SetTextureStageState( 1, D3DTSS_TEXCOORDINDEX, D3DTSS_TCI_CAMERASPACEREFLECTIONVECTOR);

	d3d_SetTextureStageState( 1, D3DTSS_COLORARG1, D3DTA_CURRENT);
	d3d_SetTextureStageState( 1, D3DTSS_COLORARG2, D3DTA_TEXTURE);
	d3d_SetTextureStageState( 1, D3DTSS_COLOROP, D3DTOP_MODULATE2X);
//	d3d_SetTextureStageState( 1, D3DTSS_COLOROP, D3DTOP_PREMODULATE);


	d3d_SetTextureStageState( 2, D3DTSS_COLOROP, D3DTOP_DISABLE);
	d3d_SetTextureStageState( 3, D3DTSS_COLOROP, D3DTOP_DISABLE);
//D3DTOP_BLENDTEXTUREALPHA


	current_render_state = ENV;
	return true;
}
stage 0 has a spec map that has just been used in a multipass specular lighting thingy, stage 1 has a cube map, currently it''s modulateing the cube map with the color of the spec map , and I want to use the alpha of the spec map instead (also if there is a way to use the specmap''s color * it''s alpha to modulate the cube map I''d like to know that as well) Bobboau, bringing you products that work... in theory

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Take a look at D3DTA_ALPHAREPLICATE - it''s a texture argument modifier flag that copies what''s in the ALPHA channel into the R,G and B channels of COLOR.

Alternatively, when you have hardware support, there are operations such as D3DTOP_MODULATEALPHA_ADDCOLOR



Simon O''Connor
Game Programmer &
Microsoft DirectX MVP

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