Quote:
Original post by Jason Z
Thanks a bunch for the demo - I will have to dig into the code later on tomorrow. Did you ever adapt your method to be able to render ridges and valleys as well? This was one of the main drivers behind my implementation - to be able to render ridges, valley, and silhouettes all at once.
Thanks again for the post, I'll give you some feedback on it as soon as I can.
Quote:Is this directed to me or to rick appleton?
Original post by edwinnie
I ran the demo and I noticed that there are some internal lines being marked as edges. Probably if its only for edges though, but seriously, these "lines" are not some of the type of silhouettes that some algorithms actually needed.
For example, there are 2 beams in the demo that forms a corner. Because the algorithm tries to follow the actual silhouette definition, the surfaces between the 2 beams that form the corner will have a line marked. But those surfaces have approximately the same surface normals since I could see that the surfaces try to touch each other.
So far, I am using the per-pixel method but with an Early-Z pass to kill off >98% of the fragments before executing a very expensive silhouette detection filter.
There are 2 other things I tried to look out in your algorithm (which I needed):
a)Are silhouettes marked only on occluding surfaces?
b)Is a there a way to directly compute a silhouette tangent?
Edwin
//-----------------------------------------------------------------------------// Edge_Mesh.fx////-----------------------------------------------------------------------------//-----------------------------------------------------------------------------// Parameters//-----------------------------------------------------------------------------float4x4 Transform : WorldViewProjection;float4x4 ModelWorld : World;float4 CamPosition : ViewPosition;float4 scale : ViewParm0 = float4(0.1,0.1,0.1,0.1); //-----------------------------------------------------------------------------// Structures//-----------------------------------------------------------------------------struct vertex{ float3 position : POSITION; float3 normal : NORMAL; float3 tangent : TANGENT; float ridge : TEXCOORD0;};//-----------------------------------------------------------------------------struct fragment{ float4 position : POSITION; float4 color : COLOR;};//-----------------------------------------------------------------------------struct pixel{ float4 color : COLOR;};//-----------------------------------------------------------------------------//-----------------------------------------------------------------------------// Vertex shaders//-----------------------------------------------------------------------------fragment VS( vertex IN ){ fragment OUT; float4 WorldPos = mul( float4(IN.position, 1), ModelWorld ); float3 P = WorldPos.xyz; float3 N = mul(IN.normal, (float3x3)ModelWorld); // world space face 1 normal float3 T = mul(IN.tangent, (float3x3)ModelWorld); // world space face 2 normal float3 E = P - CamPosition.xyz; // un-normalized world space eye to position OUT.color = 0; float EdotN = dot(E,N); // positive for forward facing, negative for back facing float EdotT = dot(E,T); // positive for forward facing, negative for back facing //float extend = 0.1 * (length(E) / 75); float extend = scale.x * (length(E) / 75); float3 newPos = IN.position + IN.normal * extend; if ( ( EdotN * EdotT ) < 0 ) // silhouette detection { OUT.color.a = 1; // make this visible OUT.color.rgb = float3( 0, 1, 0 ); if ( EdotN > 0 ) // extend only the front facing vertices { // in the opposite direction newPos = IN.position-IN.normal*extend; } } OUT.color.a += IN.ridge; // set visibility for ridges and valleys (pre-computed) OUT.position = mul( float4( newPos, 1), Transform ); // output the final vertex position return OUT;}//-----------------------------------------------------------------------------//-----------------------------------------------------------------------------// Pixel Shader//-----------------------------------------------------------------------------pixel PS( fragment IN ){ pixel OUT; OUT.color = IN.color; return OUT;}//-----------------------------------------------------------------------------// Techniques//-----------------------------------------------------------------------------technique EdgeMesh{ pass P0 { AlphaTestEnable = true; AlphaRef = 0x00000001; AlphaFunc = Greater; VertexShader = compile vs_1_1 VS(); PixelShader = compile ps_1_1 PS(); }}//-----------------------------------------------------------------------------
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