Cubemap normalization

I'm trying to get my normalmapping shader with blinn-phong specular to work on ps 1.1. I have to normalize the halfangle vector in the pixel shader but because I can't afford another normalize() (max 10 instructions..), I think I'll have to use cubemap normalization.

What I have is this:
Code:

---

c-script:
bmap NormalizeCubeMap = "normalize.dds";
..
material abc
{
   skin1 = NormalizeCubeMap;
   ..
}
..
bmap_to_cubemap(abc.skin1);

hlsl:
texture mtlSkin1;
samplerCUBE NormalizationCubeMapSampler = sampler_state
{
	Texture = <mtlSkin1>;
	MinFilter = Linear;
	MagFilter = Linear;
	MipFilter = Linear;
	AddressU  = Clamp;
	AddressV  = Clamp;
};

pixel shader:
InHalf = 2 * texCUBE(NormalizationCubeMapSampler,2 * InHalf - 1) - 1;

---

Explanation:
I first define a bitmap that contains the normalized vectors. The sides are in the following order: x, -x, y, -y, z, -z (I found this image on the web). Then I assign that bitmap as the first material skin. Then I use bmap_to_cubemap to convert the bitmap to a cubemap, I'm not sure this is needed so I also tried without that instruction and it doesn't work either. I then set up the texture and sampler in hlsl. In the pixelshader I try to normalize the vector InHalf. InHalf has been shifted to the range [0..1] so I have to shift it back to [-1..1] by 2 * InHalf - 1. Then I use that as the 3d coordinate to lookup in the cubemap. I then shift the resulting vector from [0..1] to [-1..1].

The results are wrong. It's not just inacurate it just gives incorrect results. I'm pretty sure the normalize.dds is correct (atleast it contains normalized vectors, I checked that) but I'm not too sure about the order of the sides.. Can anyone spot the mistake here?

btw, my shader works fine when I use normalize() and ps_2_0 as compile target.

Can you show your shader code where you try to normalize using the lookup? I might be able to figure it out..

btw, why do you need ps 1_1?

Hi Matt,

I use the blinn-phong algorithm that uses a halfway vector between the view and light directions.
Here is the code:
Code:

---

float4 BumpSpec_PS(	in float2 InTexN	: TEXCOORD0,
			in float3 InHalfVec	: TEXCOORD1,
			in float  InShadow	: TEXCOORD2)	: COLOR
{
	float3 BumpNormal = 2 * tex2D(NormalMapSampler, InTexN.xy) - 1.0;
	
	// Normalize halfway vector with cubemap:
//	InHalfVec = 2 * texCUBE(NormalizationCubeMapSampler,2 * InHalfVec.xyz - 1) - 1; // doesn't work..

	// Ordinary normalize:
	InHalfVec = normalize(2 * InHalfVec - 1); // Works only in ps_2_0
	
	// Calculate specular:
	float Specular = pow(saturate(dot(BumpNormal, InHalfVec)), SpecPower);
	
	// For debugging you can output the would-be normalized half vector:
//	return float4(normalize(2 * InHalfVec - 1).xyz, 1);  // How it should look
//	return 2 * texCUBE(NormalizationCubeMapSampler, 2 * InHalfVec - 1) - 1; // How it looks with cubemap normalization.
	
	return Specular.xxxx * InShadow * SpecularCoef;
}

---

Thanks for lookin into it. I could also post the whole shader, or even a demo implementation, if you can't find the error this way and you have the time to look at it..

I want my game to support ps_1_1 hardware and I'd like to enable normalmapping for the first LOD on those cards, so thats why I need ps_1_1 support.

Quote:

---

// InHalfVec = 2 * texCUBE(NormalizationCubeMapSampler,2 * InHalfVec.xyz - 1) - 1; // doesn't work..

---

EDIT:
I'm not sure but I think you cant do this kind of texture read in Ps 1_1 .. why not try doing your half vector calculation (2*half-1) in the vertex shader, then just do the normalize and expansion in the pixel shader? In other words, this is a dependent read because you are changing the texture coords in the pixel shader before loading the texture. this can only be done via some specifc instructions in versions lower than 1.4 (i could be wrong, i dont really understand this very well)

Can you post some screens or something showing with and without cubemap normalization? Also post a jpg of your cubemap, it may be set up wrong for A6; i had that problem myself.

Are you mip-mapping your cubemap? that can cause visual errors..