I'd like to have normalmapping on terrain. Has anyone got experience with this? It seems the tangents are not correct/cannot be used with terrains. The manual says:

Quote:

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Tangent
Calculates the u tangents for the 3rd texture coordinate set (TEXCOORD2). This way tangents can be used for model or level geometry shaders. The binormal vector (v tangent) can be calculated by the vertex shader from the cross product of the vertex normal and the u tangent. On animated models the tangents have to be recalculated every frame, affecting the frame rate, so don't use this flag unnecessarily.

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Does anyone know if it is possible to use normalmapping for terrains anyway?

terrains are passed to shaders just as models are...

We were talking about this in that other thread, but I guess it's moved here now, which is a better place for it anyways.

I might work on such a shader. My one question was, should there be one normal map for the whole terrain, normal maps for each texture, or both?

What do you say? single choice
	One for whole terrain
	One for each texture
	Both!
Votes accepted starting: 04/08/07 21:48 You must vote before you can view the results of this poll.

i voted for both because i could see that if you had a medium machine, you wouldnt want to use all 8 textures that'd be required for a tiled version of it, but if you do have the computing power the developer should be able to choose to use it.

I've got the shader done, but I need some textures to test it with. If you can send any of these it would be helpful...

1) grass diffuse, normal
2) dirt diffuse, normal
3) rock diffuse, normal
4) sand diffuse, normal
5) heightmap, [some kind of] normal mpa that fits it...

Eh, I'm not getting such good results.

I got the muulti-texture, and importing all the textures to the shader, that was the easy part.

I'm having trouble getting the normals to react to light correctly. The dot product of the normals gives me results, but when moving the sun, it's as if the sun never moved. they stay the same, but the lighting of the face adjusts.

Not sure why this is, I'm gonna go do more testing...

I'm using the "tangent, binormal, normal" system that I've sen many times before. And it's the same system I used in the "Best VSPS shader"...

Any ideas?

I'll send you the code I've done tomorrow... (Which is actually later today, lol)...

yeah, I'm out for tonight. but I'm still not sure why the shader isn't working. It is a strange result, and hard to explain without showing. it worked in the normal mapping shader I posted, but not in this one. With a model terrain too! why?


Code:

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{
    Vertex Shader:
	float3x3 worldToTangentSpace;
	worldToTangentSpace[0] = mul(inTangent, matWorld);
	worldToTangentSpace[1] = mul(cross(inTangent, inNormal), matWorld);
	worldToTangentSpace[2] = mul(inNormal, matWorld);

	Out.Sun = mul(worldToTangentSpace, -vecSunDir);


    Pixel Shader:
	float4 output = saturate(dot(bumpNormal, In.Sun))l
	return output;
}

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I'm out for the night. Sorry. Too much "Russian mineral water"...

I've just verified it again: the tangent passed to a terrain entity is always 0,0,0. Try outputting it as a color in the pixel shader..

I think you can calculate the tangent and binormal from only the normal because you know that it's a regular grid (u and v always pointing in xz direction).

So you'd take the cross of the normal and a (unit?) vector pointing in x (or z?) direction to get the tangent and then cross that with the normal to get the binormal or something..

PS. I'm talking about the directX coordinate system here, so z = y.


EDIT: I was creating this shader for a client who is using 6.31.4. I just tried it in 6.50, and it does give some kind of a tangent there, but I'm getting the impression it's still not quite right..

EDIT2: Yes I'm now convinced that in 6.50, the tangents are wrong. Try outputting the tangent as a color on a terrain and then convert that terrain to a mdl and do it again. The tangents look somewhat like they should be, but there are some strange things.. I guess it's a bug, or we're not supposed to use them with terrains (and have to calculate them from the normal).

EDIT3:
Ok, I can calculate the tangent and binormal from the normal on a terrain. This works on a model terrain, but when I use it on a terrain, I get the SAME tangents as when I use the tangent flag.. Seems like the problem is related to the normals then..
worldToTangentSpace[0] = cross(InNorm, float3(0.0f, 0.0f, 1.0f));
worldToTangentSpace[1] = cross(worldToTangentSpace[0], InNorm);
worldToTangentSpace[2] = InNorm;

EDIT4: Ok, after calling ent_fixnormals everything works fine.. Strange!
I would advise you to use the above way of calculating the tangent and not use the tangent flag, because it is faster on the GPU. Ofcourse it only works for terrains. EDIT: it's not faster