1 | /* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */ |
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2 | /* |
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3 | * Copyright (c) 2004-2013 HUBzero Foundation, LLC |
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4 | * |
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5 | * Authors: |
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6 | * Wei Qiao <qiaow@purdue.edu> |
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7 | */ |
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8 | |
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9 | // constrain particle to be outside volume of a sphere |
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10 | void SphereConstraint(inout float3 x, float3 center, float r) |
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11 | { |
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12 | float3 delta = x - center; |
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13 | float dist = length(delta); |
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14 | if (dist < r) { |
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15 | x = center + delta*(r / dist); |
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16 | } |
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17 | } |
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18 | |
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19 | // constrain particle to be above floor |
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20 | void FloorConstraint(inout float3 x, float level) |
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21 | { |
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22 | if (x.y < level) { |
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23 | x.y = level; |
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24 | } |
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25 | } |
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26 | |
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27 | // constrain particle to heightfield stored in texture |
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28 | void TerrainConstraint(inout float3 pos, uniform sampler2D terrain_tex, |
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29 | float3 scale, float3 offset) |
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30 | { |
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31 | float2 uv = (pos.xz - offset.xz) / scale.xz; |
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32 | float h = tex2D(terrain_tex, uv).r*scale.y + offset.y; |
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33 | if (pos.y < h) { |
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34 | pos.y = h; |
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35 | } |
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36 | } |
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37 | |
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38 | void SphereCollide(inout float3 x, inout float3 vel, float3 center, float r, |
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39 | float3 sphere_vel, float friction, inout float3 force) |
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40 | { |
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41 | float3 delta = x - center; |
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42 | float dist = length(delta); |
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43 | if (dist < r) { |
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44 | // x = center + delta*(r / dist); |
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45 | vel += (delta / dist) * friction; |
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46 | vel += sphere_vel; |
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47 | } |
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48 | } |
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49 | |
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50 | void FloorCollide(inout float3 x, inout float3 vel, float level, |
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51 | float friction, inout float3 force) |
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52 | { |
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53 | if (x.y < level) { |
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54 | // x.y = level; |
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55 | // force.y += -vel.y*friction; |
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56 | vel.y += -vel.y*friction; |
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57 | } |
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58 | } |
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59 | |
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60 | void Gravitation(float3 pos, float3 mass_pos, inout float3 force, float epsilon) |
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61 | { |
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62 | float3 delta = mass_pos - pos; |
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63 | float dist = length(delta); |
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64 | float3 dir = delta / dist; |
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65 | force += dir * (1.0 / (epsilon + dist*dist)); |
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66 | } |
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67 | |
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68 | void TerrainCollide(float3 pos, inout float3 vel, uniform sampler2D terrain_tex, |
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69 | float3 scale, float3 offset, float friction) |
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70 | { |
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71 | const float2 texelSize = float2( 1.0 / 256.0, 1.0 / 256.0 ); |
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72 | float2 uv = (pos.xz - offset.xz) / scale.xz; |
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73 | float h0 = tex2D(terrain_tex, uv).r; |
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74 | float h = h0*scale.y + offset.y; |
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75 | if (pos.y < h) { |
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76 | // calculate normal (could precalc this) |
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77 | float h1 = tex2D(terrain_tex, uv + texelSize*float2(1, 0) ).r; |
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78 | float h2 = tex2D(terrain_tex, uv + texelSize*float2(0, 1) ).r; |
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79 | float3 N = cross(float3(scale.x*texelSize.x, (h1-h0)*scale.y, 0), |
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80 | float3(0, (h2-h0)*scale.y, scale.z*texelSize.y)); |
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81 | N = normalize(N); |
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82 | vel = reflect(vel, N); |
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83 | vel *= friction; |
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84 | } |
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85 | } |
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86 | |
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87 | struct a2v |
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88 | { |
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89 | //For semantics, see pages 230-240 of Cg_Toolkit.pdf |
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90 | float4 Position : POSITION; |
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91 | float4 TexCoord : TEXCOORD0; |
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92 | }; |
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93 | |
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94 | struct v2f |
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95 | { |
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96 | float4 HPosition: HPOS; //Clip space pos. Not readable in frag prog |
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97 | float4 TexCoord : TEXCOORD0; |
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98 | float3 EyeVector: TEXCOORD1; //world space eye vector |
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99 | float3 Light : TEXCOORD2; //world space light vector |
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100 | }; |
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101 | |
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102 | struct PixelOut { |
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103 | float4 Color: COLOR0; |
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104 | //float Depth: DEPTH; |
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105 | }; |
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