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 | // update velocity and position in a single pass using MRT |
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10 | |
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11 | #include "common.cg" |
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12 | |
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13 | void main(in float2 uv : TEXCOORD0, |
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14 | uniform samplerRECT pos_tex, |
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15 | uniform samplerRECT vel_tex, |
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16 | uniform sampler2D terrain_tex, |
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17 | uniform float timestep = 0.01, |
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18 | uniform float damping = 0.99, |
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19 | uniform float3 gravity = float3(0, -1, 0), |
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20 | uniform float3 spherePos, |
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21 | uniform float3 sphereVel, |
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22 | out float4 new_pos : COLOR0, |
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23 | out float4 new_vel : COLOR1) |
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24 | { |
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25 | const float3 terrain_scale = float3(8.0, 2.0, 8.0); |
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26 | const float3 terrain_offset = float3(-4.0, 0.01, -4.0); |
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27 | |
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28 | float3 pos = texRECT(pos_tex, uv).xyz; |
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29 | float3 vel = texRECT(vel_tex, uv).xyz; |
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30 | |
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31 | float3 pos_next = pos + vel * timestep; // predicted position next timestep |
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32 | |
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33 | // update velocity |
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34 | float3 force = gravity; |
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35 | // float3 force = 0.0; |
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36 | // Gravitation(pos, spherePos, force, 0.1); |
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37 | |
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38 | SphereCollide(pos_next, vel, spherePos, 1.0, sphereVel, 0.5, force); |
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39 | // FloorCollide(pos_next, vel, 0.0, 0.5, force); |
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40 | TerrainCollide(pos_next, vel, terrain_tex, terrain_scale, terrain_offset, 0.5); |
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41 | |
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42 | const float inv_mass = 1.0; |
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43 | vel += force * inv_mass * timestep; // F = ma |
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44 | vel *= damping; |
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45 | |
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46 | // update position |
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47 | SphereConstraint(pos, spherePos, 1.0f); |
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48 | // FloorConstraint(pos, 0.0f); |
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49 | TerrainConstraint(pos, terrain_tex, terrain_scale, terrain_offset); |
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50 | |
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51 | pos += vel * timestep; |
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52 | |
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53 | new_vel = float4(vel, 1); |
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54 | new_pos = float4(pos, 1); |
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55 | } |
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