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ComputeTangent()

Started by Bulma Jul 14, 2004 at 9:17 AM 1 replies 1.5k views

Original Post

Jul 14, 2004 at 9:17 AM

Hopefully I`ll get some answers here ;) I have a typical mesh with Position, Normal and Texture coordinates... I have code that goes like this:


Mesh original = Mesh.FromFile(...)
VertexElement[] decl = original.Declaration;
decl[3] = new VertexElement(0, 32, DeclarationType.Float3,
DeclarationMethod.Default, DeclarationUsage.Tangent, 0);
decl[4] = new VertexElement(0, 44, DeclarationType.Float3,
DeclarationMethod.Default, DeclarationUsage.BiNormal, 0);
decl[5] = VertexElement.VertexDeclarationEnd;
bumpMappedMesh = original.Clone(MeshFlags.Managed, decl, original.Device );
bumpMappedMesh.ComputeTangent(0, 0, 0, 0);

In my shader i have:


VS_OUTPUT VS( float4 Pos : POSITION, float3 Norm : NORMAL, float2 Tex :
TEXCOORD0, float3 Tangent : TANGENT0, float3 Binormal : BINORMAL0 )
{
    VS_OUTPUT Out = (VS_OUTPUT)0;
    ....

I checked with shader debugger and I get all values for Tangent and Binormal = (0,0,0); Other values (position, normal, tex) are ok... I tried with different objects too... What am I doing wrong? No errors with maximum validation...

IFooBar

Jul 14, 2004 at 9:44 AM

not quite sure this will work, but try to change your code to:

decl[3] = new VertexElement(0, 32, DeclarationType.Float3,DeclarationMethod.Default, DeclarationUsage.Tangent, 1);decl[4] = new VertexElement(0, 44, DeclarationType.Float3,DeclarationMethod.Default, DeclarationUsage.BiNormal, 2);

and then call Compute Tangent as:

bumpMappedMesh.ComputeTangent(0, 1, 2, 1);

[edit]

Actually, yeah, that *should* work. Because if you specify 0 as the tangentIndex and 0 as the binormalIndex, then ComputeTangent doesnt touch the tangent and binormal data. But you also have to change the usage index of your declarations to match teh new usage indices of the tangent and binormal data

[/edit]

Bulma

Jul 14, 2004 at 4:09 PM

I tried that, but it still doesn`t work... Still zeros for binormal and tangent :(

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