1 | #version 150 |
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2 | |
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3 | // Ogre port of Nvidia's IsoSurf.cg file |
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4 | // Modified code follows. See http://developer.download.nvidia.com/SDK/10/opengl/samples.html for original |
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5 | // |
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6 | // Cg port of Yury Uralsky's metaball FX shader |
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7 | // |
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8 | // Authors: Simon Green and Yury Urlasky |
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9 | // Email: sdkfeedback@nvidia.com |
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10 | // |
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11 | // Copyright (c) NVIDIA Corporation. All rights reserved. |
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12 | //////////////////////////////////////////////////////////////////////////////////////////////////// |
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13 | |
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14 | uniform float IsoValue = 1.0; |
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15 | uniform mat4 WorldViewProj; |
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16 | uniform mat4 origWorldViewIT; |
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17 | |
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18 | // Size of the sampling grid |
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19 | const ivec3 SizeMask = ivec3( 63, 63, 63 ); |
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20 | const ivec3 SizeShift = ivec3( 0, 6, 12 ); |
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21 | uniform vec4 Metaballs[2] = vec4[](vec4( -0.5, 0, 0, 0.2 ), vec4( 0.6, 0, 0, 0.1 )); |
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22 | |
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23 | in vec4 vertex; |
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24 | |
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25 | out VertexData { |
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26 | vec3 N; |
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27 | vec2 Field; |
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28 | } VertexOut; |
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29 | |
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30 | // Metaball function |
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31 | // Returns metaball function value in .w and its gradient in .xyz |
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32 | |
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33 | vec4 Metaball(vec3 Pos, vec3 Center, float RadiusSq) |
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34 | { |
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35 | const float epsilon = 0.001; |
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36 | |
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37 | vec3 Dist = Pos - Center; |
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38 | float InvDistSq = 1 / (dot(Dist, Dist) + epsilon); |
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39 | |
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40 | vec4 o; |
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41 | o.xyz = -2 * RadiusSq * InvDistSq * InvDistSq * Dist; |
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42 | o.w = RadiusSq * InvDistSq; |
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43 | return o; |
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44 | } |
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45 | |
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46 | void main() |
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47 | { |
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48 | // Sum up contributions from all metaballs |
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49 | /* vec4 Field; |
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50 | for (int i = 0; i<2; i++) |
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51 | { |
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52 | Field += Metaball(vertex.xyz, Metaballs[i].xyz, Metaballs[i].w); |
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53 | } |
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54 | |
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55 | mat3 WorldViewIT = mat3(origWorldViewIT[0].xyz, origWorldViewIT[1].xyz, origWorldViewIT[2].xyz); |
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56 | |
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57 | // Transform position and normals |
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58 | gl_Position = WorldViewProj * vertex; |
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59 | VertexOut.N = WorldViewIT * Field.xyz; // we want normals in world space |
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60 | VertexOut.Field.x = Field.w; |
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61 | |
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62 | // Generate in-out flags |
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63 | VertexOut.Field.y = (Field.w < 1.0) ? 1 : 0; |
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64 | */ |
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65 | vec3 Pos; |
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66 | |
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67 | // Generate sampling point position based on its index |
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68 | Pos.x = float((gl_VertexID >> SizeShift.x) & SizeMask.x) / (SizeMask.x + 1); |
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69 | Pos.y = float((gl_VertexID >> SizeShift.y) & SizeMask.y) / (SizeMask.y + 1); |
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70 | Pos.z = float((gl_VertexID >> SizeShift.z) & SizeMask.z) / (SizeMask.z + 1); |
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71 | Pos = Pos*2 - 1; |
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72 | |
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73 | // Sum up contributions from all metaballs |
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74 | vec4 Field; |
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75 | for (int i = 0; i<2; i++) |
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76 | Field += Metaball(Pos, Metaballs[i].xyz, Metaballs[i].w); |
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77 | |
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78 | // Transform position and normals |
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79 | gl_Position = WorldViewProj * vec4(Pos, 1); |
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80 | VertexOut.N = mat3(origWorldViewIT) * Field.xyz; // we want normals in world space |
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81 | VertexOut.Field.x = Field.w; |
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82 | |
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83 | // Generate in-out flags |
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84 | VertexOut.Field.y = (Field.w < IsoValue) ? 1 : 0; |
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85 | |
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86 | // o.Color = (Field*0.5+0.5) * (Field.w / 10.0); |
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87 | } |
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