matTangent

Typ:

Bemerkungen:

• Der binormale Vektor lässt sich vom Vertex-Shader aus dem Kreuzprodukt von Vertex-Normale und Tangente berechnen.
• Bei animierten Modellen müssen die Tangenten mit jedem Frame neu berechnet werden, was die Framerate beeinflusst. Setzen Sie die Tangenten-Matrix daher mit Bedacht ein.

Edition:

Beispiel:

// normal mapping effect for vs 1.1 / ps 1.1
texture entSkin1;	// texture
texture entSkin2;	// normal map

sampler sBaseTex = sampler_state { Texture = <entSkin1>; };
sampler sBump = sampler_state { Texture = <entSkin2>; };

float4 vecSunDir;
float4x4 matWorldViewProj;
float3x3 matTangent;	// hint for the engine to create tangents in TEXCOORD2

// create a matrix for conversion to tangent space
void CreateTangents(float3 inNormal,float3 inTangent)
{
	matTangent[0] = mul(inTangent,matWorld);
	matTangent[1] = mul(cross(inTangent,inNormal),matWorld);	// binormal
	matTangent[2] = mul(inNormal,matWorld);
}

struct out_bump
{
 	float4 Pos:     POSITION;
 	float2 Tex:   	TEXCOORD0;
 	float2 Bump:   	TEXCOORD1;
 	float3 Light:	TEXCOORD2;
};

out_bump vs_bump(
	in float4 inPos: 	POSITION, 
	in float3 inNormal:	NORMAL,
	in float2 inTex: 	TEXCOORD0,
	in float3 inTangent: TEXCOORD2)
{
	out_bump Out;
	Out.Pos	= mul(inPos,matWorldViewProj);
	Out.Tex	= inTex;
	Out.Bump = inTex;	// must be different coordinates for ps_1_1
		
	CreateTangents(inNormal,inTangent);
// convert the sun vector to tangent space
// and transform the output values to the 0..1 range 
// that is required for passing them to the pixel shader 
	Out.Light = normalize(mul(matTangent,-vecSunDir)) * 0.5 + 0.5;
	return Out;		
}

float4 ps_bump(out_bump In): COLOR
{
	float4 texture = tex2D(sBaseTex,In.Tex);
	float3 bumpNormal = tex2D(sBump,In.Bump);
// transform values back to the -1..+1 range 
	float diffuse = saturate(dot(In.Light*2 - 1,bumpNormal*2 - 1));
	return texture * diffuse;
}

technique NormalMapping
{
	pass One
	{		
		VertexShader = compile vs_1_1 vs_bump();
		PixelShader = compile ps_1_1 ps_bump();
	}
}

Siehe auch:

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