私は現在、directx9 で作業しており、通常のマッピングには次のコードがあります。
(頂点シェーダー):
float4x4 gWorldMatrix;
float4x4 gWorldViewProjectionMatrix;
float4 gWorldLightPosition;
float4 gWorldCameraPosition;
struct VS_INPUT
{
float4 mPosition : POSITION;
float3 mNormal: NORMAL;
float3 mTangent: TANGENT;
float3 mBinormal: BINORMAL;
float2 mUV: TEXCOORD0;
};
struct VS_OUTPUT
{
float4 mPosition : POSITION;
float2 mUV: TEXCOORD0;
float3 mLightDir: TEXCOORD1;
float3 mViewDir: TEXCOORD2;
float3 T: TEXCOORD3;
float3 B: TEXCOORD4;
float3 N: TEXCOORD5;
};
VS_OUTPUT vs_main( VS_INPUT Input )
{
VS_OUTPUT Output;
Output.mPosition = mul( Input.mPosition, gWorldViewProjectionMatrix );
Output.mUV = Input.mUV;
float4 worldPosition = mul( Input.mPosition, gWorldMatrix );
float3 lightDir = worldPosition.xyz - gWorldLightPosition.xyz;
Output.mLightDir = normalize( lightDir );
float3 viewDir = normalize( worldPosition.xyz - gWorldCameraPosition.xyz );
Output.mViewDir = viewDir;
//object space=>world space
float3 worldNormal = mul( Input.mNormal, (float3x3)gWorldMatrix );
Output.N = normalize( worldNormal );
float3 worldTangent = mul( Input.mTangent, (float3x3)gWorldMatrix );
Output.T = normalize( worldTangent );
float3 worldBinormal = mul( Input.mBinormal, (float3x3)gWorldMatrix );
Output.B = normalize( worldBinormal);
return Output;
}
(ピクセルシェーダー)
struct PS_INPUT
{
float2 mUV : TEXCOORD0;
float3 mLightDir: TEXCOORD1;
float3 mViewDir: TEXCOORD2;
float3 T: TEXCOORD3;
float3 B: TEXCOORD4;
float3 N: TEXCOORD5;
};
sampler2D DiffuseSampler;
sampler2D SpecularSampler;
sampler2D NormalSampler;
float3 gLightColor;
float4 ps_main(PS_INPUT Input) : COLOR
{
//read normal from tex
float3 tangentNormal = tex2D( NormalSampler, Input.mUV ).xyz;
tangentNormal = normalize( tangentNormal * 2 - 1 ); //convert 0~1 to -1~+1.
//read from vertex shader
float3x3 TBN = float3x3( normalize(Input.T), normalize(Input.B),
normalize(Input.N) ); //transforms world=>tangent space
TBN = transpose( TBN ); //transform tangent space=>world
float3 worldNormal = mul( TBN, tangentNormal ); //note: mat * scalar
//(since TBN is row matrix)
float3 lightDir = normalize( Input.mLightDir );
float3 diffuse = saturate( dot(worldNormal, -lightDir) );
float4 albedo = tex2D( DiffuseSampler, Input.mUV );
diffuse = gLightColor * albedo.rgb * diffuse;
float3 specular = 0;
if ( diffuse.x > 0 )
{
float3 reflection = reflect( lightDir, worldNormal );
float3 viewDir = normalize( Input.mViewDir );
specular = saturate( dot(reflection, -viewDir) );
specular = pow( specular, 20.0f );
//further adjustments to specular (since texture is 2D)
float specularIntensity = tex2D( SpecularSampler, Input.mUV );
specular *= specularIntensity * gLightColor;
}
float3 ambient = float3(0.1f, 0.1f, 0.1f) * albedo;
return float4(ambient + diffuse + specular, 1);
}
コードは機能しますが、なぜ実行する必要があるのか よくわかりません
TBN = transpose( TBN );
ピクセルシェーダーで。
Vertex Shader を介して渡した TBN 値はワールド空間のものです (したがって、gWorldMatrix を乗算した理由)。
float3x3 TBN = float3x3( normalize(Input.T), normalize(Input.B),
normalize(Input.N) );
ワールド=>タンジェント(サーフェス)空間を変換します。
どうしてこれなの?