11fa2e8b43
See also http://code.google.com/p/bullet/issues/detail?id=390 Added Demos/DX11ClothDemo (an OpenCL cloth demo will follow soon)
91 lines
2.8 KiB
Common Lisp
91 lines
2.8 KiB
Common Lisp
MSTRINGIFY(
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/*#define float3 float4
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float dot3(float3 a, float3 b)
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{
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return a.x*b.x + a.y*b.y + a.z*b.z;
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}*/
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float3 projectOnAxis( float3 v, float3 a )
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{
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return (a*dot(v, a));
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}
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__kernel void
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ApplyForcesKernel(
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const uint numNodes,
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const float solverdt,
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const float epsilon,
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__global int * g_vertexClothIdentifier,
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__global float4 * g_vertexNormal,
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__global float * g_vertexArea,
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__global float * g_vertexInverseMass,
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__global float * g_clothLiftFactor,
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__global float * g_clothDragFactor,
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__global float4 * g_clothWindVelocity,
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__global float4 * g_clothAcceleration,
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__global float * g_clothMediumDensity,
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__global float4 * g_vertexForceAccumulator,
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__global float4 * g_vertexVelocity)
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{
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unsigned int nodeID = get_global_id(0);
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if( nodeID < numNodes )
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{
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int clothId = g_vertexClothIdentifier[nodeID];
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float nodeIM = g_vertexInverseMass[nodeID];
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if( nodeIM > 0.0f )
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{
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float3 nodeV = g_vertexVelocity[nodeID].xyz;
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float3 normal = g_vertexNormal[nodeID].xyz;
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float area = g_vertexArea[nodeID];
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float3 nodeF = g_vertexForceAccumulator[nodeID].xyz;
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// Read per-cloth values
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float3 clothAcceleration = g_clothAcceleration[clothId].xyz;
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float3 clothWindVelocity = g_clothWindVelocity[clothId].xyz;
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float liftFactor = g_clothLiftFactor[clothId];
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float dragFactor = g_clothDragFactor[clothId];
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float mediumDensity = g_clothMediumDensity[clothId];
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// Apply the acceleration to the cloth rather than do this via a force
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nodeV += (clothAcceleration*solverdt);
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g_vertexVelocity[nodeID] = (float4)(nodeV, 0.f);
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float3 relativeWindVelocity = nodeV - clothWindVelocity;
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float relativeSpeedSquared = dot(relativeWindVelocity, relativeWindVelocity);
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if( relativeSpeedSquared > epsilon )
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{
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// Correct direction of normal relative to wind direction and get dot product
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normal = normal * (dot(normal, relativeWindVelocity) < 0 ? -1.f : 1.f);
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float dvNormal = dot(normal, relativeWindVelocity);
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if( dvNormal > 0 )
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{
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float3 force = (float3)(0.f, 0.f, 0.f);
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float c0 = area * dvNormal * relativeSpeedSquared / 2.f;
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float c1 = c0 * mediumDensity;
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force += normal * (-c1 * liftFactor);
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force += normalize(relativeWindVelocity)*(-c1 * dragFactor);
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float dtim = solverdt * nodeIM;
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float3 forceDTIM = force * dtim;
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float3 nodeFPlusForce = nodeF + force;
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// m_nodesf[i] -= ProjectOnAxis(m_nodesv[i], force.normalized())/dtim;
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float3 nodeFMinus = nodeF - (projectOnAxis(nodeV, normalize(force))/dtim);
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nodeF = nodeFPlusForce;
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if( dot(forceDTIM, forceDTIM) > dot(nodeV, nodeV) )
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nodeF = nodeFMinus;
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g_vertexForceAccumulator[nodeID] = (float4)(nodeF, 0.0f);
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}
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}
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}
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}
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}
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); |