GteFluid2UpdateState.cpp

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// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2017
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// File Version: 3.0.0 (2016/06/19)

#include <GTEnginePCH.h>
#include <Physics/GteFluid2UpdateState.h>
#include <Graphics/GteGraphicsEngine.h>
#include <Graphics/GteProgramFactory.h>
using namespace gte;

Fluid2UpdateState::Fluid2UpdateState(std::shared_ptr<ProgramFactory> const& factory,
    int xSize, int ySize, int numXThreads, int numYThreads,
    std::shared_ptr<ConstantBuffer> const& parameters)
    :
    mNumXGroups(xSize/numXThreads),
    mNumYGroups(ySize/numYThreads)
{
    mUpdateState = std::make_shared<Texture2>(DF_R32G32B32A32_FLOAT, xSize, ySize);
    mUpdateState->SetUsage(Resource::SHADER_OUTPUT);

    mAdvectionSampler = std::make_shared<SamplerState>();
    mAdvectionSampler->filter = SamplerState::MIN_L_MAG_L_MIP_P;
    mAdvectionSampler->mode[0] = SamplerState::CLAMP;
    mAdvectionSampler->mode[1] = SamplerState::CLAMP;

    // Create the shader for generating velocity from vortices.
    int i = factory->GetAPI();
    factory->PushDefines();
    factory->defines.Set("NUM_X_THREADS", numXThreads);
    factory->defines.Set("NUM_Y_THREADS", numYThreads);

    mComputeUpdateState = factory->CreateFromSource(*msSource[i]);
    if (mComputeUpdateState)
    {
        std::shared_ptr<ComputeShader> cshader =  mComputeUpdateState->GetCShader();
        cshader->Set("Parameters", parameters);
#if defined(GTE_DEV_OPENGL)
        cshader->Set("stateTm1", mAdvectionSampler);
#else
        cshader->Set("advectionSampler", mAdvectionSampler);
#endif
        cshader->Set("updateState", mUpdateState);
    }

    factory->PopDefines();
}

void Fluid2UpdateState::Execute(std::shared_ptr<GraphicsEngine> const& engine,
    std::shared_ptr<Texture2> const& source,
    std::shared_ptr<Texture2> const& stateTm1,
    std::shared_ptr<Texture2> const& stateT)
{
    std::shared_ptr<ComputeShader> cshader = mComputeUpdateState->GetCShader();
    cshader->Set("source", source);
    cshader->Set("stateTm1", stateTm1);
    cshader->Set("stateT", stateT);
    engine->Execute(mComputeUpdateState, mNumXGroups, mNumYGroups, 1);
}


std::string const Fluid2UpdateState::msGLSLSource =
"uniform Parameters\n"
"{\n"
"    vec4 spaceDelta;    // (dx, dy, 0, 0)\n"
"    vec4 halfDivDelta;  // (0.5/dx, 0.5/dy, 0, 0)\n"
"    vec4 timeDelta;     // (dt/dx, dt/dy, 0, dt)\n"
"    vec4 viscosityX;    // (velVX, velVX, 0, denVX)\n"
"    vec4 viscosityY;    // (velVX, velVY, 0, denVY)\n"
"    vec4 epsilon;       // (epsilonX, epsilonY, 0, epsilon0)\n"
"};\n"
"\n"
"layout(rgba32f) uniform readonly image2D source;\n"
"layout(rgba32f) uniform readonly image2D stateT;\n"
"uniform sampler2D stateTm1;\n"
"layout(rgba32f) uniform writeonly image2D updateState;\n"
"\n"
"layout (local_size_x = NUM_X_THREADS, local_size_y = NUM_Y_THREADS, local_size_z = 1) in;\n"
"void main()\n"
"{\n"
"    ivec2 c = ivec2(gl_GlobalInvocationID.xy);\n"
"    ivec2 dim = imageSize(stateT);\n"
"\n"
"    int x = int(c.x);\n"
"    int y = int(c.y);\n"
"    int xm = max(x - 1, 0);\n"
"    int xp = min(x + 1, dim.x - 1);\n"
"    int ym = max(y - 1, 0);\n"
"    int yp = min(y + 1, dim.y - 1);\n"
"\n"
"    // Sample states at (x,y), (x+dx,y), (x-dx,y), (x,y+dy), (x,y-dy).\n"
"    vec4 stateZZ = imageLoad(stateT, c);\n"
"    vec4 statePZ = imageLoad(stateT, ivec2(xp, y));\n"
"    vec4 stateMZ = imageLoad(stateT, ivec2(xm, y));\n"
"    vec4 stateZP = imageLoad(stateT, ivec2(x, yp));\n"
"    vec4 stateZM = imageLoad(stateT, ivec2(x, ym));\n"
"\n"
"    // Sample the source state at (x,y).\n"
"    vec4 src = imageLoad(source, c);\n"
"\n"
"    // Estimate second-order derivatives of state at (x,y).\n"
"    vec4 stateDXX = statePZ - 2.0f*stateZZ + stateMZ;\n"
"    vec4 stateDYY = stateZP - 2.0f*stateZZ + stateZM;\n"
"\n"
"    // Compute advection.\n"
"    vec2 tcd = spaceDelta.xy*(c.xy - timeDelta.xy*stateZZ.xy + 0.5f);\n"
"    vec4 advection = textureLod(stateTm1, tcd, 0.0f);\n"
"\n"
"    // Update the state.\n"
"    imageStore(updateState, c, advection +\n"
"        (viscosityX*stateDXX + viscosityY*stateDYY + timeDelta.w*src));\n"
"}\n";

std::string const Fluid2UpdateState::msHLSLSource =
"cbuffer Parameters\n"
"{\n"
"    float4 spaceDelta;    // (dx, dy, 0, 0)\n"
"    float4 halfDivDelta;  // (0.5/dx, 0.5/dy, 0, 0)\n"
"    float4 timeDelta;     // (dt/dx, dt/dy, 0, dt)\n"
"    float4 viscosityX;    // (velVX, velVX, 0, denVX)\n"
"    float4 viscosityY;    // (velVX, velVY, 0, denVY)\n"
"    float4 epsilon;       // (epsilonX, epsilonY, 0, epsilon0)\n"
"};\n"
"\n"
"Texture2D<float4> source;\n"
"Texture2D<float4> stateTm1;\n"
"Texture2D<float4> stateT;\n"
"SamplerState advectionSampler;  // bilinear, clamp\n"
"RWTexture2D<float4> updateState;\n"
"\n"
"[numthreads(NUM_X_THREADS, NUM_Y_THREADS, 1)]\n"
"void CSMain(uint2 c : SV_DispatchThreadID)\n"
"{\n"
"    uint2 dim;\n"
"    stateT.GetDimensions(dim.x, dim.y);\n"
"\n"
"    int x = int(c.x);\n"
"    int y = int(c.y);\n"
"    int xm = max(x - 1, 0);\n"
"    int xp = min(x + 1, dim.x - 1);\n"
"    int ym = max(y - 1, 0);\n"
"    int yp = min(y + 1, dim.y - 1);\n"
"\n"
"    // Sample states at (x,y), (x+dx,y), (x-dx,y), (x,y+dy), (x,y-dy).\n"
"    float4 stateZZ = stateT[int2(x, y)];\n"
"    float4 statePZ = stateT[int2(xp, y)];\n"
"    float4 stateMZ = stateT[int2(xm, y)];\n"
"    float4 stateZP = stateT[int2(x, yp)];\n"
"    float4 stateZM = stateT[int2(x, ym)];\n"
"\n"
"    // Sample the source state at (x,y).\n"
"    float4 src = source[int2(x, y)];\n"
"\n"
"    // Estimate second-order derivatives of state at (x,y).\n"
"    float4 stateDXX = statePZ - 2.0f*stateZZ + stateMZ;\n"
"    float4 stateDYY = stateZP - 2.0f*stateZZ + stateZM;\n"
"\n"
"    // Compute advection.\n"
"    float2 tcd = spaceDelta.xy*(c - timeDelta.xy*stateZZ.xy + 0.5f);\n"
"    float4 advection = stateTm1.SampleLevel(advectionSampler, tcd, 0.0f);\n"
"\n"
"    // Update the state.\n"
"    updateState[c] = advection +\n"
"        (viscosityX*stateDXX + viscosityY*stateDYY + timeDelta.w*src);\n"
"}\n";

std::string const* Fluid2UpdateState::msSource[] =
{
    &msGLSLSource,
    &msHLSLSource
};