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source: data/data_extern/programs/Cg/varianceshadowcasterfp.cg @ 12294

Last change on this file since 12294 was 12115, checked in by wiesep, 6 years ago

Changed folder structure, deletet some unused files and cleaned up code

File size: 2.6 KB
Line 
1/////////////////////////////////////////////////////////////////////////////////
2//
3// shadowcasterfp.cg
4//
5// Hamilton Chong
6// (c) 2006
7//
8// This is an example fragment shader for shadow caster objects. 
9//
10/////////////////////////////////////////////////////////////////////////////////
11
12
13// Define outputs from vertex shader.
14struct VertexOut
15{
16  float4 position   : POSITION;     // can't rely on access to this
17  float4 pos        : TEXCOORD0;    // position of fragment (in homogeneous coordinates)
18  float4 normal     : TEXCOORD1;    // un-normalized normal in object space
19  float4 modelPos   : TEXCOORD2;    // coordinates of model in object space at this point
20};
21
22struct FragmentOut
23{
24    float4 color  : COLOR0;
25};
26
27FragmentOut main( VertexOut        In,                     // fragment to process
28                  uniform float    uDepthOffset,           // offset amount (constant in eye space)
29                  uniform float4x4 uProjection             // projection matrix
30              )
31{
32    FragmentOut Out;
33
34    // compute the "normalized device coordinates" (no viewport applied yet)
35    float4 postproj = In.pos / In.pos.w;
36
37    // get the normalized normal of the geometry seen at this point
38    float4 normal = normalize(In.normal);
39
40
41    // -- Computing Depth Bias Quantities -----------------------------
42
43    // We now compute the change in z that would signify a push in the z direction
44    // by 1 unit in eye space.  Note that eye space z is related in a nonlinear way to
45    // screen space z, so this is not just a constant. 
46    // ddepth below is how much screen space z at this point would change for that push.
47    // NOTE: computation of ddepth likely differs from OpenGL's glPolygonOffset "unit"
48    //  computation, which is allowed to be vendor specific.
49    float4 dpwdz = mul(uProjection, float4(0.0, 0.0, 1.0, 0.0));
50    float4 dpdz = (dpwdz - (postproj * dpwdz.w)) / In.pos.w;
51    float  ddepth = abs(dpdz.z);
52
53    // -- End depth bias helper section --------------------------------   
54
55    // We now compute the depth of the fragment.  This is the actual depth value plus
56    // our depth bias.  The depth bias depends on how uncertain we are about the z value
57    // plus some constant push in the z direction.  The exact coefficients to use are
58    // up to you, but at least it should be somewhat intuitive now what the tradeoffs are.
59    float depthval = postproj.z /* + (0.5 * dzlen)*/ + (uDepthOffset * ddepth);
60    depthval = (0.5 * depthval) + 0.5; // put into [0,1] range instead of [-1,1]
61
62   
63    Out.color = float4(depthval, depthval * depthval, depthval, 0.0);
64    return Out;
65}
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