Method Particles

GTE/Graphics/Particles.cpp:14–71

using namespace gte;

Particles::Particles(std::vector<Vector4<float>> const& positionSize,
    float sizeAdjust, VertexFormat const& vformat)
    :
    mPositionSize(positionSize),
    mSizeAdjust(sizeAdjust),
    mNumActive(static_cast<uint32_t>(positionSize.size()))
{
    uint32_t texOffset = IsValid(vformat);
    if (texOffset == std::numeric_limits<uint32_t>::max())
    {
        // IsValid(...) will generate logging messages depending on the
        // specific failure condition.
        return;
    }

    uint32_t numParticles = mNumActive;
    uint32_t numVertices = 4 * numParticles;
    mVBuffer = std::make_shared<VertexBuffer>(vformat, numVertices);
    mVBuffer->SetUsage(Resource::Usage::DYNAMIC_UPDATE);
    uint32_t vertexSize = vformat.GetVertexSize();
    int32_t index = vformat.GetIndex(VASemantic::TEXCOORD, 0);
    uint32_t offset = vformat.GetOffset(index);
    char* tcoords = mVBuffer->GetData() + offset;
    std::array<Vector2<float>, 4> commonTCD =
    {
        Vector2<float>{ 0.0f, 0.0f },
        Vector2<float>{ 1.0f, 0.0f },
        Vector2<float>{ 1.0f, 1.0f },
        Vector2<float>{ 0.0f, 1.0f }
    };
    for (uint32_t i = 0; i < numParticles; ++i)
    {
        for (uint32_t j = 0; j < 4; ++j)
        {
            Vector2<float>& tcoord = *reinterpret_cast<Vector2<float>*>(tcoords);
            tcoord = commonTCD[j];
            tcoords += vertexSize;
        }
    }

    mIBuffer = std::make_shared<IndexBuffer>(IP_TRIMESH, 2 * numParticles, sizeof(uint32_t));
    auto* indices = mIBuffer->Get<uint32_t>();
    for (uint32_t i = 0; i < numParticles; ++i)
    {
        uint32_t iFI = 4 * i;
        uint32_t iFIp1 = iFI + 1;
        uint32_t iFIp2 = iFI + 2;
        uint32_t iFIp3 = iFI + 3;
        *indices++ = iFI;
        *indices++ = iFIp1;
        *indices++ = iFIp2;
        *indices++ = iFI;
        *indices++ = iFIp2;
        *indices++ = iFIp3;
    }

    UpdateModelBound();
}