I'm trying to set the color and alpha channel for volumetric lines.
How do I set the lines diffuse color and alpha channel?
I tried adding DWORD color; to the vertex structure and setting the FVF to:
static const DWORD FVF = D3DFVF_XYZ | D3DFVF_DIFFUSE | D3DFVF_NORMAL |
D3DFVF_TEX2 | // D3DFVF_TEX2 specifies we have two sets of texture coordinates.
D3DFVF_TEXCOORDSIZE4(0) | // This specifies that the first (0th) tex coord set has size 4 floats.
D3DFVF_TEXCOORDSIZE3(1); // Specifies that second tex coord set has size 2 floats.
D3DFVF_TEX2 | // D3DFVF_TEX2 specifies we have two sets of texture coordinates.
D3DFVF_TEXCOORDSIZE4(0) | // This specifies that the first (0th) tex coord set has size 4 floats.
D3DFVF_TEXCOORDSIZE3(1); // Specifies that second tex coord set has size 2 floats.
But, not working.
Vertex structure:
struct TVertex
{
D3DXVECTOR3 pos;
D3DXVECTOR3 otherPos;
D3DXVECTOR4 texOffset;
D3DXVECTOR3 thickness;
static const DWORD FVF = D3DFVF_XYZ | D3DFVF_NORMAL |
D3DFVF_TEX2 | // D3DFVF_TEX2 specifies we have two sets of texture coordinates.
D3DFVF_TEXCOORDSIZE4(0) | // This specifies that the first (0th) tex coord set has size 4 floats.
D3DFVF_TEXCOORDSIZE3(1); // Specifies that second tex coord set has size 2 floats.
};
Effect file:
//////////////////////
// Volume line shader. Based on the CG Volume Lines sample from NVidia.
float4x4 mWVP : WorldViewProjection;
float4x4 mWV : WorldView;
texture lineTexture;
sampler textureSampler = sampler_state
{
Texture = (lineTexture);
MipFilter = LINEAR;
MinFilter = LINEAR;
MagFilter = LINEAR;
};
struct TInputVertex
{
float4 pos : POSITION; // Position of this vertex
float4 otherPos : NORMAL; // Position of the other vertex at the other end of the line.
float4 texOffset : TEXCOORD0; // Tex coord offset.
float3 thickness : TEXCOORD1; // Thickness info.
};
struct TOutputVertex
{
float4 hPos : POSITION;
float blend : COLOR0;
float4 tex0 : TEXCOORD0;
float4 tex1 : TEXCOORD1;
};
TOutputVertex VolumeLineVS( TInputVertex IN )
{
TOutputVertex OUT = (TOutputVertex)0;
// World*View transformation.
float4 posStart = mul( IN.pos, mWV );
float4 posEnd = mul( IN.otherPos, mWV );
// Unit vector between eye and center of the line.
float3 middlePoint = normalize( (posStart.xyz + posEnd.xyz) / 2.0 );
// Unit vector of the line direction.
float3 lineOffset = posEnd.xyz - posStart.xyz;
float3 lineDir = normalize( lineOffset );
float lineLenSq = dot( lineOffset, lineOffset );
// Dot product to compute texture coef
float texCoef = abs( dot( lineDir, middlePoint ) );
// Change texture coef depending on line length: y=(Sz/(l^2))(x-1)+1
texCoef = max( ( (texCoef - 1) * (lineLenSq / IN.thickness.z ) ) + 1, 0 );
posStart = mul( IN.pos, mWVP );
posEnd = mul( IN.otherPos, mWVP );
// Project these points in screen space.
float2 startPos2D = posStart.xy / posStart.w;
float2 endPos2D = posEnd.xy / posEnd.w;
// Calculate 2D line direction.
float2 lineDir2D = normalize( startPos2D - endPos2D );
// Shift vertices along 2D projected line
posStart.xy += ((texCoef * IN.texOffset.x) * lineDir2D.xy);
// Shift vertex for thickness perpendicular to line direction.
lineDir2D *= IN.thickness.x;
posStart.x += lineDir2D.y;
posStart.y -= lineDir2D.x;
OUT.hPos = posStart;
// Compute tex coords depending on texCoef.
float4 tex;
tex.zw = float2(0,1);
tex.y = min(15.0/16.f, texCoef);
tex.x = modf(tex.y * 4.0, tex.y);
OUT.blend = modf(tex.x * 4.0, tex.x);
tex.xy = (tex.xy / 4.0) + (IN.texOffset).zw;
tex.y = 1-tex.y;
OUT.tex0 = tex;
// Now get the second texture coord : increment.
tex.y = min(texCoef + (1.0/16.f), 15.0/16.0 );
tex.x = modf(tex.y * 4.0, tex.y);
tex.x = floor(tex.x * 4.0);
tex.xy = (tex.xy / 4) + (IN.texOffset).zw;
tex.y = 1-tex.y;
OUT.tex1 = tex;
return OUT;
}
float4 VolumeLinePS( TOutputVertex IN ) : COLOR
{
float4 blendFactor = IN.blend;
float4 c0 = tex2D( textureSampler, IN.tex0 );
float4 c1 = tex2D( textureSampler, IN.tex1 );
return lerp( c0, c1, blendFactor );
}
technique VolumeLine
{
pass p0
{
CullMode = none;
AlphaBlendEnable = true;
SrcBlend = one;
DestBlend = one;
alpharef = 0.9;
alphafunc = GreaterEqual;
ZEnable = false;
VertexShader = compile vs_2_0 VolumeLineVS();
PixelShader = compile ps_2_0 VolumeLinePS();
}
}
