等值面纹理问题

时间:2012-04-17 22:08:48

标签: camera directx pixel hlsl shader

我目前在使用行进四面体算法生成的网格纹理时遇到问题。代码位于.fx HLSL文件中。 问题的描述可能是纹理似乎根据相机的位置移动。因此,例如,如果相机左右扫射,纹理也会随之左右移动。左右摇摄相机时也会出现问题。

这是一个奇怪的效果,而且很难描述,所以我附上了一些图像,纹理AddressU和AddressV设置为Clamp,因此更容易证明问题​​。

http://i.imgur.com/JbyVZ.png

http://i.imgur.com/nDkB1.png

如您所见,向右移动相机也会将纹理向右移动。

我可能错过了一些完全明显的东西,比如乘以某个矩阵(我试过)。任何帮助都将不胜感激。

这是我的像素着色器代码。

float4 DiffusePS( SurfaceVertex IN ) : SV_Target

{

float4 AmbientColor = float4(0.2, 0.2, 0.2, 1);
float AmbientIntensity = 0.2;

float4 Kd = 0.5;
float4 diffuseLight = 0.5;

float4 Pos = GetWorldSpacePos( IN.Pos );
float3 N = normalize(IN.N);
float3 L1 = normalize(LightPos1 - Pos.xyz);
float3 L2 = normalize(LightPos2 - Pos.xyz);
float3 L3 = normalize(LightPos3 - Pos.xyz);

float NdotL1 = max(0, dot(N, L1));
float NdotL2 = max(0, dot(N, L2));
float NdotL3 = max(0, dot(N, L3));

float3 I = normalize(Pos.xyz);
float3 V = normalize(-Pos.xyz);

float4 vDiff = diffuseLight * Kd * NdotL1;
float4 vDiff2 = diffuseLight * Kd * NdotL2;
float4 vDiff3 = diffuseLight * Kd * NdotL3;

float3 Color = vDiff + vDiff2 + vDiff3;
float4 derp = rockTexture.Sample(RockSampler, IN.tex.xy);

return lerp(derp ,float4(Color, 1), 0.5);

感谢您的帮助

编辑:.fx文件的其余部分

#define MAX_METABALLS   400
#define IOR             2.5

#define PI 3.1415

Buffer<float4> SampleDataBuffer;

struct SampleData
{
    float4 Pos : SV_Position;
    float4 Field : TEXCOORD0;   // Gradient in .xyz, value in .w
};

struct SurfaceVertex
{
    float4 Pos : SV_Position;
    float3 N : NORMAL;
    float2 tex : TEXCOORD;
};

cbuffer constants
{
    float R0Constant = ((1.0 - (1.0/IOR)) * (1.0 - (1.0/IOR))) / ((1.0 + (1.0/IOR)) * (1.0 + (1.0/IOR)));
    float R0Inv = 1.0 - ((1.0 - (1.0/IOR)) * (1.0 - (1.0/IOR)))/((1.0 + (1.0/IOR)) * (1.0 + (1.0/IOR)));
};


cbuffer cb0 : register(b0)
{
    row_major float4x4 ProjInv;
    row_major float3x3 ViewIT;
    row_major float4x4 WorldViewProj;
    row_major float4x4 World;

    uint NumMetaballs;
    float4 Metaballs[MAX_METABALLS];    // .xyz -> metaball center, .w -> metaball squared radius

    float3 ViewportOrg;
    float3 ViewportSizeInv;

    float3 LightPos1;        // view-space light position 1
    float3 LightPos2;        // view-space light position 2
    float3 LightPos3;        // view-space light position 3


};

Texture2D rockTexture;

SamplerState RockSampler
{
    Filter = MIN_MAG_MIP_LINEAR;
    AddressU = Wrap;
    AddressV = Wrap;
};



float4 GetWorldSpacePos( float4 WindowPos )
{
    float4 ClipPos;
    ClipPos.x = (2 * ((WindowPos.x - ViewportOrg.x) * ViewportSizeInv.x) - 1);
    ClipPos.y = (-2 * ((WindowPos.y - ViewportOrg.y) * ViewportSizeInv.y) + 1);
    ClipPos.z = ((WindowPos.z - ViewportOrg.z) * ViewportSizeInv.z);
    ClipPos.w = 1;

    float4 Pos;
    Pos = mul(ClipPos, ProjInv);    // backtransform clipspace position to get viewspace position
    Pos.xyz /= Pos.w;               // re-normalize


    return Pos;
}


// Metaball function
// Returns metaball function value in .w and its gradient in .xyz
float4 Metaball(float3 Pos, float3 Center, float RadiusSq)
{
    float4 o;

    float3 d = Pos - Center;
    float DistSq = dot(d, d);
    float InvDistSq = 1 / DistSq;

    o.xyz = -2 * RadiusSq * InvDistSq * InvDistSq * d;
    o.w = RadiusSq * InvDistSq;

    return o;
}


SamplerState TriLinearSampler
{
    Filter = MIN_MAG_MIP_LINEAR;
    AddressU = WRAP;
    AddressV = WRAP;
};


// Vertex shader calculates field contributions at each grid vertex
SampleData SampleFieldVS(float3 Pos : POSITION)
{
    SampleData o;

    float3 WorldPos = mul(float4(Pos, 1), World).xyz;

    // Sum up contributions from all metaballs

    o.Field = 0;

    for (uint i = 0; i<NumMetaballs; i++)
    {
        //o.Field += WorldPos.y;
        o.Field += Metaball(WorldPos, Metaballs[i].xyz, Metaballs[i].w);


    }
    // Transform position and normals


    o.Pos = mul(float4(Pos.xyz, 1), WorldViewProj);
    o.Field.xyz = -normalize(mul(o.Field.xyz, ViewIT));  // we want normals in view space


    // Generate in-out flags

    return o;
}



SampleData PassThroughVS(SampleData IN)
{
    SampleData OUT;
    OUT = IN;
    return OUT;
}

// Estimate where isosurface intersects grid edge with endpoints v0, v1
SurfaceVertex CalcIntersection(SampleData v0, SampleData v1)
{
    SurfaceVertex o;

    // We're taking special care to generate bit-exact results regardless of traversal (v0,v1) or (v1, v0)

    float t = (2.0 - (v0.Field.w + v1.Field.w)) / (v1.Field.w - v0.Field.w);

    o.Pos = 0.5 * (t * (v1.Pos - v0.Pos) + (v1.Pos + v0.Pos));
    o.N = 0.5 * (t * (v1.Field.xyz - v0.Field.xyz) + (v1.Field.xyz + v0.Field.xyz));    

    float4 worldPos = mul(World, o.Pos);
    o.tex = worldPos.xy;

    return o;
}

// This struct stores vertex indices of up to 4 edges from the input tetrahedron. The GS code below 
// uses these indices to index into the input vertex set for interpolation along those edges. 
// It basically encodes topology for the output triangle strip (of up to 2 triangles).
struct TetrahedronIndices 
{ 
    uint4 e0; 
    uint4 e1; 
};

[MaxVertexCount(4)]
void TessellateTetrahedraGS(lineadj SampleData In[4], inout TriangleStream<SurfaceVertex> Stream)
{
    // construct index for this tetrahedron
    uint index = (uint(In[0].Field.w > 1) << 3) | (uint(In[1].Field.w > 1) << 2) | (uint(In[2].Field.w > 1) << 1) | uint(In[3].Field.w > 1);


    // don't bother if all vertices out or all vertices in
    if (index > 0 && index < 15)
    {
        uint4 e0 = EdgeTableGS[index].e0;
        uint4 e1 = EdgeTableGS[index].e1;

        // Emit a triangle
        Stream.Append( CalcIntersection(In[e0.x], In[e0.y]) );
        Stream.Append( CalcIntersection(In[e0.z], In[e0.w]) );
        Stream.Append( CalcIntersection(In[e1.x], In[e1.y]) );

        // Emit additional triangle, if necessary
        if (e1.z != 0) {
            Stream.Append( CalcIntersection(In[e1.z], In[e1.w]) );
        }

    }
}

TextureCube EnvMap;

float FresnelApprox(float3 I, float3 N)
{
    return R0Constant + R0Inv * pow(1.0 - dot(I, N), 5.0);
}

float4 ShadeSurfacePS( SurfaceVertex IN ) : SV_Target
{
    float4 Pos = GetWorldSpacePos( IN.Pos );

    float3 N = normalize(IN.N);
    float3 L1 = normalize(LightPos1 - Pos.xyz);
    float3 L2 = normalize(LightPos2 - Pos.xyz);
    float3 L3 = normalize(LightPos3 - Pos.xyz);
    float3 I = normalize(Pos.xyz);

    float3 R = reflect(I, N);

    float4 Reflected = EnvMap.Sample( TriLinearSampler, mul(ViewIT, R ) );

    float NdotL1 = max(0, dot(N, L1));
    float NdotL2 = max(0, dot(N, L2));
    float NdotL3 = max(0, dot(N, L3));

    float3 Color = NdotL1 * float3(1, 1, 1) + pow(max(dot(R, L1), 0), 32)
                    + NdotL2 * float3(0.65, 0.6, 0.45) + pow(max(dot(R, L2), 0), 32)
                    + NdotL3 * float3(0.7, 0.7, 0.8) + pow(max(dot(R, L3), 0), 32);

    return lerp(EnvMap.Sample( TriLinearSampler, mul(ViewIT, R) ), float4(Color, 1), FresnelApprox(I, N) * 0.05 );

}

float4 SimplePS( SurfaceVertex IN, uniform float4 color ) : SV_Target
{
    return color;
}

float4 DiffusePS( SurfaceVertex IN ) : SV_Target
{

    float4 AmbientColor = float4(0.2, 0.2, 0.2, 1);
    float AmbientIntensity = 0.2;

    float4 Kd = 0.5;
    float4 diffuseLight = 0.5;

    float4 Pos = GetWorldSpacePos( IN.Pos );
    float3 N = normalize(IN.N);
    float3 L1 = normalize(LightPos1 - Pos.xyz);
    float3 L2 = normalize(LightPos2 - Pos.xyz);
    float3 L3 = normalize(LightPos3 - Pos.xyz);

    float NdotL1 = max(0, dot(N, L1));
    float NdotL2 = max(0, dot(N, L2));
    float NdotL3 = max(0, dot(N, L3));

    float3 I = normalize(Pos.xyz);
    float3 V = normalize(-Pos.xyz);

    float4 vDiff = diffuseLight * Kd * NdotL1;
    float4 vDiff2 = diffuseLight * Kd * NdotL2;
    float4 vDiff3 = diffuseLight * Kd * NdotL3;

    float3 Color = vDiff + vDiff2 + vDiff3;
    float4 derp = rockTexture.Sample(RockSampler, IN.tex.xy);

    return lerp(derp ,float4(Color, 1), 0.5);
    //return lerp(NoiseTexture.Sample( NoiseSampler, IN.tex ), float4(Color, 1), FresnelApprox(V, N) * 0.05 );

    //return saturate(vDiff+vDiff2+vDiff3 + AmbientColor * AmbientIntensity);


}

DepthStencilState EnableDepthDSS
{
    DepthEnable = true;
    DepthWriteMask = 1;
};

RasterizerState WireFrameRS
{
    MultiSampleEnable = True;
    CullMode = None;
    FillMode = WireFrame;
};

RasterizerState SolidRS
{
    MultiSampleEnable = True;
    CullMode = None;
    FillMode = Solid;
};


technique10 MarchingTetrahedraWireFrame
{
    pass P0
    {
        SetRasterizerState( WireFrameRS );
        SetDepthStencilState( EnableDepthDSS, 0 );

        SetVertexShader( CompileShader( vs_4_0, SampleFieldVS() ) );
        SetGeometryShader( CompileShader( gs_4_0, TessellateTetrahedraGS() ) );
        SetPixelShader( CompileShader( ps_4_0, SimplePS( float4( 0.7, 0.7, 0.7, 1 ) ) ) );
    }
}

// Tessellate isosurface in a single pass
technique10 MarchingTetrahedraSinglePassGS
{
    pass P0
    {
        SetRasterizerState( SolidRS );
        SetDepthStencilState( EnableDepthDSS, 0 );

        SetVertexShader( CompileShader( vs_4_0, SampleFieldVS() ) );
        SetGeometryShader( CompileShader( gs_4_0, TessellateTetrahedraGS() ) );
        SetPixelShader( CompileShader( ps_4_0, DiffusePS() ) );
    }
}

// Tessellate isosurface in two passes, streaming out VS results in-between
GeometryShader StreamOutGS = ConstructGSWithSO( CompileShader( vs_4_0, PassThroughVS() ), "SV_Position.xyzw; TEXCOORD0.xyzw" );

technique10 MarchingTetrahedraMultiPassGS
{
    pass P0
    {
        SetVertexShader( CompileShader( vs_4_0, SampleFieldVS() ) );
        SetGeometryShader( StreamOutGS );
        SetPixelShader( NULL );
    }

    pass P1
    {

        SetRasterizerState( SolidRS );
        SetDepthStencilState( EnableDepthDSS, 0 );

        SetVertexShader( CompileShader ( vs_4_0, PassThroughVS() ) );
        SetGeometryShader( CompileShader( gs_4_0, TessellateTetrahedraGS() ) );
        SetPixelShader( CompileShader( ps_4_0, DiffusePS() ) );
    }
}

1 个答案:

答案 0 :(得分:0)

当前通过将顶点位置乘以世界矩阵生成纹理坐标:

CalcIntersection()
....
    float4 worldPos = mul(World, o.Pos);
    o.tex = worldPos.xy;
....

因此,摄像机平移必须改变其中一个输入。猜测它可能是世界矩阵(即摄像机平移实际上是被移动的对象),尝试切换到不依赖于世界矩阵的纹理坐标生成方法。 e.g:

CalcIntersection()
...
    o.tex = o.Pos.xy;
...


编辑:由于这不起作用,它必须是摄像机平移修改的位置,并且看着SampleFieldVS()有一条似乎在做的行:

o.Pos = mul(float4(Pos.xyz, 1), WorldViewProj);

因此,您需要做的是在修改之前保存位置。您必须将它保存在SampleData中,因此请在SampleData结构的末尾添加它:

float2 tex1 : TEXCOORD1;

然后在SampleFieldVS()

的末尾添加保存行
o.tex1 = mul(float4(Pos.xyz, 0), World).xy;

最后删除' float4 worldPos = mul(World,o.Pos); o.tex = worldPos.xy; '在CalcIntersection()的末尾并替换为:

o.tex = 0.5 * (t * (v1.tex1 - v0.tex1) + (v1.tex1 + v0.tex1));