GteFluid2AdjustVelocity.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/GteFluid2AdjustVelocity.h>
#include <Graphics/GteGraphicsEngine.h>
#include <Graphics/GteProgramFactory.h>
using namespace gte;

Fluid2AdjustVelocity::Fluid2AdjustVelocity(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)
{
    int i = factory->GetAPI();
    factory->PushDefines();
    factory->defines.Set("NUM_X_THREADS", numXThreads);
    factory->defines.Set("NUM_Y_THREADS", numYThreads);

    mAdjustVelocity = factory->CreateFromSource(*msSource[i]);
    if (mAdjustVelocity)
    {
        mAdjustVelocity->GetCShader()->Set("Parameters", parameters);
    }

    factory->PopDefines();
}

void Fluid2AdjustVelocity::Execute(std::shared_ptr<GraphicsEngine> const& engine,
    std::shared_ptr<Texture2> const& inState,
    std::shared_ptr<Texture2> const& poisson,
    std::shared_ptr<Texture2> const& outState)

{
    std::shared_ptr<ComputeShader> cshader = mAdjustVelocity->GetCShader();
    cshader->Set("inState", inState);
    cshader->Set("poisson", poisson);
    cshader->Set("outState", outState);
    engine->Execute(mAdjustVelocity, mNumXGroups, mNumYGroups, 1);
}


std::string const Fluid2AdjustVelocity::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 inState;\n"
"layout(r32f) uniform readonly image2D poisson;\n"
"layout(rgba32f) uniform writeonly image2D outState;\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(inState);\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 the state at (x,y).\n"
"    vec4 state = imageLoad(inState, c);\n"
"\n"
"    // Sample Poisson values at immediate neighbors of (x,y).\n"
"    float poisPZ = imageLoad(poisson, ivec2(xp, y)).x;\n"
"    float poisMZ = imageLoad(poisson, ivec2(xm, y)).x;\n"
"    float poisZP = imageLoad(poisson, ivec2(x, yp)).x;\n"
"    float poisZM = imageLoad(poisson, ivec2(x, ym)).x;\n"
"\n"
"    vec4 diff = vec4(poisPZ - poisMZ, poisZP - poisZM, 0.0f, 0.0f);\n"
"    imageStore(outState, c, state + halfDivDelta*diff);\n"
"}\n";

std::string const Fluid2AdjustVelocity::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> inState;\n"
"Texture2D<float> poisson;\n"
"RWTexture2D<float4> outState;\n"
"\n"
"[numthreads(NUM_X_THREADS, NUM_Y_THREADS, 1)]\n"
"void CSMain(uint2 c : SV_DispatchThreadID)\n"
"{\n"
"    uint2 dim;\n"
"    inState.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 the state at (x,y).\n"
"    float4 state = inState[c];\n"
"\n"
"    // Sample Poisson values at immediate neighbors of (x,y).\n"
"    float poisPZ = poisson[int2(xp, y)];\n"
"    float poisMZ = poisson[int2(xm, y)];\n"
"    float poisZP = poisson[int2(x, yp)];\n"
"    float poisZM = poisson[int2(x, ym)];\n"
"\n"
"    float4 diff = float4(poisPZ - poisMZ, poisZP - poisZM, 0.0f, 0.0f);\n"
"    outState[c] = state + halfDivDelta*diff;\n"
"}\n";

std::string const* Fluid2AdjustVelocity::msSource[] =
{
    &msGLSLSource,
    &msHLSLSource
};