static unsafe void RunCompute(Sample sample, bool indirectSupported)
{
// build vertex layouts
var quadLayout = new VertexLayout();
quadLayout.Begin()
.Add(VertexAttributeUsage.Position, 2, VertexAttributeType.Float)
.End();
var computeLayout = new VertexLayout();
computeLayout.Begin()
.Add(VertexAttributeUsage.TexCoord0, 4, VertexAttributeType.Float)
.End();
// static quad data
var vb = new VertexBuffer(MemoryBlock.FromArray(QuadVertices), quadLayout);
var ib = new IndexBuffer(MemoryBlock.FromArray(QuadIndices));
// create compute buffers
var currPositionBuffer0 = new DynamicVertexBuffer(1 << 15, computeLayout, BufferFlags.ComputeReadWrite);
var currPositionBuffer1 = new DynamicVertexBuffer(1 << 15, computeLayout, BufferFlags.ComputeReadWrite);
var prevPositionBuffer0 = new DynamicVertexBuffer(1 << 15, computeLayout, BufferFlags.ComputeReadWrite);
var prevPositionBuffer1 = new DynamicVertexBuffer(1 << 15, computeLayout, BufferFlags.ComputeReadWrite);
// load shaders
var particleProgram = ResourceLoader.LoadProgram("vs_particle", "fs_particle");
var initInstancesProgram = ResourceLoader.LoadProgram("cs_init_instances");
var updateInstancesProgram = ResourceLoader.LoadProgram("cs_update_instances");
// indirect rendering support
var indirectProgram = SharpBgfx.Program.Invalid;
var indirectBuffer = IndirectBuffer.Invalid;
bool useIndirect = false;
if (indirectSupported)
{
indirectProgram = ResourceLoader.LoadProgram("cs_indirect");
indirectBuffer = new IndirectBuffer(2);
useIndirect = true;
}
// setup params uniforms
var paramData = new ParamsData {
TimeStep = 0.0157f,
DispatchSize = 32,
Gravity = 0.109f,
Damping = 0.25f,
ParticleIntensity = 0.64f,
ParticleSize = 0.279f,
BaseSeed = 57,
ParticlePower = 3.5f,
InitialSpeed = 3.2f,
InitialShape = 1,
MaxAccel = 100.0f
};
// have the compute shader run initialization
var u_params = new Uniform("u_params", UniformType.Vector4, 3);
Bgfx.SetUniform(u_params, ¶mData, 3);
Bgfx.SetComputeBuffer(0, prevPositionBuffer0, ComputeBufferAccess.Write);
Bgfx.SetComputeBuffer(1, currPositionBuffer0, ComputeBufferAccess.Write);
Bgfx.Dispatch(0, initInstancesProgram, MaxParticleCount / ThreadGroupUpdateSize);
// start the frame clock
var clock = new Clock();
clock.Start();
// main loop
while (sample.ProcessEvents(ResetFlags.Vsync))
{
// tick the clock
var elapsed = clock.Frame();
var time = clock.TotalTime();
// write some debug text
Bgfx.DebugTextClear();
Bgfx.DebugTextWrite(0, 1, DebugColor.White, DebugColor.Blue, "SharpBgfx/Samples/24-NBody");
Bgfx.DebugTextWrite(0, 2, DebugColor.White, DebugColor.Cyan, "Description: N-body simulation with compute shaders using buffers.");
Bgfx.DebugTextWrite(0, 3, DebugColor.White, DebugColor.Cyan, "Frame: {0:F3} ms", elapsed * 1000);
// fill the indirect buffer if we're using it
if (useIndirect)
{
Bgfx.SetUniform(u_params, ¶mData, 3);
Bgfx.SetComputeBuffer(0, indirectBuffer, ComputeBufferAccess.Write);
Bgfx.Dispatch(0, indirectProgram);
}
// update particle positions
Bgfx.SetComputeBuffer(0, prevPositionBuffer0, ComputeBufferAccess.Read);
Bgfx.SetComputeBuffer(1, currPositionBuffer0, ComputeBufferAccess.Read);
Bgfx.SetComputeBuffer(2, prevPositionBuffer1, ComputeBufferAccess.Write);
Bgfx.SetComputeBuffer(3, currPositionBuffer1, ComputeBufferAccess.Write);
Bgfx.SetUniform(u_params, ¶mData, 3);
if (useIndirect)
{
Bgfx.Dispatch(0, updateInstancesProgram, indirectBuffer, 1);
}
else
{
Bgfx.Dispatch(0, updateInstancesProgram, paramData.DispatchSize);
}
// ping-pong the buffers for next frame
Swap(ref currPositionBuffer0, ref currPositionBuffer1);
Swap(ref prevPositionBuffer0, ref prevPositionBuffer1);
// view transforms for particle rendering
var viewMatrix = Matrix4x4.CreateLookAt(new Vector3(0.0f, 0.0f, -45.0f), -Vector3.UnitZ, Vector3.UnitY);
var projMatrix = Matrix4x4.CreatePerspectiveFieldOfView((float)Math.PI / 4, (float)sample.WindowWidth / sample.WindowHeight, 0.1f, 10000.0f);
Bgfx.SetViewTransform(0, &viewMatrix.M11, &projMatrix.M11);
Bgfx.SetViewRect(0, 0, 0, sample.WindowWidth, sample.WindowHeight);
// draw the particles
Bgfx.SetVertexBuffer(vb);
Bgfx.SetIndexBuffer(ib);
Bgfx.SetInstanceDataBuffer(currPositionBuffer0, 0, paramData.DispatchSize * ThreadGroupUpdateSize);
Bgfx.SetRenderState(RenderState.ColorWrite | RenderState.BlendAdd | RenderState.DepthTestAlways);
if (useIndirect)
{
Bgfx.Submit(0, particleProgram, indirectBuffer);
}
else
{
Bgfx.Submit(0, particleProgram);
}
// done with frame
Bgfx.Frame();
}
// cleanup
if (indirectSupported)
{
indirectProgram.Dispose();
indirectBuffer.Dispose();
}
u_params.Dispose();
currPositionBuffer0.Dispose();
currPositionBuffer1.Dispose();
prevPositionBuffer0.Dispose();
prevPositionBuffer1.Dispose();
updateInstancesProgram.Dispose();
initInstancesProgram.Dispose();
particleProgram.Dispose();
ib.Dispose();
vb.Dispose();
}
