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// This code contains NVIDIA Confidential Information and is disclosed to you
// under a form of NVIDIA software license agreement provided separately to you.
//
// Notice
// NVIDIA Corporation and its licensors retain all intellectual property and
// proprietary rights in and to this software and related documentation and
// any modifications thereto. Any use, reproduction, disclosure, or
// distribution of this software and related documentation without an express
// license agreement from NVIDIA Corporation is strictly prohibited.
//
// ALL NVIDIA DESIGN SPECIFICATIONS, CODE ARE PROVIDED "AS IS.". NVIDIA MAKES
// NO WARRANTIES, EXPRESSED, IMPLIED, STATUTORY, OR OTHERWISE WITH RESPECT TO
// THE MATERIALS, AND EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF NONINFRINGEMENT,
// MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE.
//
// Information and code furnished is believed to be accurate and reliable.
// However, NVIDIA Corporation assumes no responsibility for the consequences of use of such
// information or for any infringement of patents or other rights of third parties that may
// result from its use. No license is granted by implication or otherwise under any patent
// or patent rights of NVIDIA Corporation. Details are subject to change without notice.
// This code supersedes and replaces all information previously supplied.
// NVIDIA Corporation products are not authorized for use as critical
// components in life support devices or systems without express written approval of
// NVIDIA Corporation.
//
// Copyright (c) 2013-2020 NVIDIA Corporation. All rights reserved.
#include "flexExt_dx_common.h"
#define kNumThreadsPerBlock 256
cbuffer consts : register(b0) { FlexExtConstParams gParams; };
namespace UpdateForceFields
{
StructuredBuffer<float4> positions : register(t0);
StructuredBuffer<FlexExtForceFieldD3D> forceFields : register(t1);
RWStructuredBuffer<float4> velocities : register(u0);
[numthreads(kNumThreadsPerBlock, 1, 1)] void execute(uint3 globalIdx : SV_DispatchThreadID)
{
const int i = globalIdx.x;
const int numParticles = gParams.kNumParticles;
const int numForceFields = gParams.kNumForceFields;
const float dt = gParams.kDt;
for (int f = 0; f < numForceFields; f++)
{
const FlexExtForceFieldD3D forceField = forceFields[f];
if (i < numParticles)
{
const int index = i;
float4 p = positions[index];
float3 v = velocities[index].xyz;
float3 localPos = float3(p.x, p.y, p.z) - float3(forceField.mPosition[0], forceField.mPosition[1], forceField.mPosition[2]);
float dist = length(localPos);
if (dist >= forceField.mRadius)
{
continue;
}
float3 fieldDir;
if (dist > 0.0f)
{
fieldDir = localPos / dist;
}
else
{
fieldDir = localPos;
}
// If using linear falloff, scale with distance.
float fieldStrength = forceField.mStrength;
if (forceField.mLinearFalloff)
{
fieldStrength *= (1.0f - (dist / forceField.mRadius));
}
// Apply force
float3 force = localPos * fieldStrength;
float unitMultiplier;
if (forceField.mMode == eNvFlexExtModeForce)
{
unitMultiplier = dt * p.w; // time/mass
}
else if (forceField.mMode == eNvFlexExtModeImpulse)
{
unitMultiplier = p.w; // 1/mass
}
else if (forceField.mMode == eNvFlexExtModeVelocityChange)
{
unitMultiplier = 1.0f;
}
float3 deltaVelocity = fieldDir * fieldStrength * unitMultiplier;
velocities[index] = float4(v + deltaVelocity, 0.0f);
}
}
}
}
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