1 | /*
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2 | * ======================================================================
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3 | * AUTHOR: Wei Qiao <qiaow@purdue.edu>
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4 | * Purdue Rendering and Perceptualization Lab (PURPL)
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5 | *
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6 | * Copyright (c) 2004-2006 Purdue Research Foundation
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7 | *
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8 | * See the file "license.terms" for information on usage and
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9 | * redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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10 | * ======================================================================
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11 | */
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12 |
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13 | // update velocity based on acceleration
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14 |
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15 | #include "common.cg"
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16 |
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17 | float4 main(in float2 uv : TEXCOORD0,
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18 |
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19 | uniform samplerRECT pos_tex,
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20 | uniform samplerRECT vel_tex,
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21 | uniform sampler2D terrain_tex,
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22 |
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23 | uniform float timestep = 0.01,
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24 | uniform float damping = 0.99,
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25 | uniform float3 gravity = float3(0, -1, 0),
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26 | uniform float3 spherePos,
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27 | uniform float3 sphereVel
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28 | ) : COLOR
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29 | {
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30 | const float3 terrain_scale = float3(8.0, 2.0, 8.0);
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31 | const float3 terrain_offset = float3(-4.0, 0.01, -4.0);
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32 |
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33 | float3 pos = texRECT(pos_tex, uv).xyz;
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34 | float3 vel = texRECT(vel_tex, uv).xyz;
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35 |
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36 | float3 pos_next = pos + vel * timestep; // predicted position next timestep
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37 |
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38 | float3 force = gravity;
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39 | // float3 force = 0.0;
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40 | // Gravitation(pos, spherePos, force, 0.1);
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41 |
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42 | SphereCollide(pos_next, vel, spherePos, 1.0, sphereVel, 0.5, force);
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43 | // FloorCollide(pos_next, vel, 0.0, 0.5, force);
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44 | TerrainCollide(pos_next, vel, terrain_tex, terrain_scale, terrain_offset, 0.5);
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45 |
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46 | const float inv_mass = 1.0;
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47 | vel += force * inv_mass * timestep; // F = ma
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48 | vel *= damping;
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49 |
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50 | return float4(vel, 1.0);
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51 | }
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