in unity/Assets/PostProcessingV2/Runtime/Monitors/WaveformMonitor.cs [48:106]
internal override void Render(PostProcessRenderContext context)
{
// Waveform show localized data, so width depends on the aspect ratio
float ratio = (context.width / 2f) / (context.height / 2f);
int width = Mathf.FloorToInt(height * ratio);
CheckOutput(width, height);
exposure = Mathf.Max(0f, exposure);
int count = width * height;
if (m_Data == null)
{
m_Data = new ComputeBuffer(count, sizeof(uint) << 2);
}
else if (m_Data.count < count)
{
m_Data.Release();
m_Data = new ComputeBuffer(count, sizeof(uint) << 2);
}
var compute = context.resources.computeShaders.waveform;
var cmd = context.command;
cmd.BeginSample("Waveform");
var parameters = new Vector4(
width,
height,
RuntimeUtilities.isLinearColorSpace ? 1 : 0,
0f
);
// Clear the buffer on every frame
int kernel = compute.FindKernel("KWaveformClear");
cmd.SetComputeBufferParam(compute, kernel, "_WaveformBuffer", m_Data);
cmd.SetComputeVectorParam(compute, "_Params", parameters);
cmd.DispatchCompute(compute, kernel, Mathf.CeilToInt(width / (float)m_ThreadGroupSizeX), Mathf.CeilToInt(height / (float)m_ThreadGroupSizeY), 1);
// For performance reasons, especially on consoles, we'll just downscale the source
// again to reduce VMEM stalls. Eventually the whole algorithm needs to be rewritten as
// it's currently pretty naive.
cmd.GetTemporaryRT(ShaderIDs.WaveformSource, width, height, 0, FilterMode.Bilinear, context.sourceFormat);
cmd.BlitFullscreenTriangle(ShaderIDs.HalfResFinalCopy, ShaderIDs.WaveformSource);
// Gather all pixels and fill in our waveform
kernel = compute.FindKernel("KWaveformGather");
cmd.SetComputeBufferParam(compute, kernel, "_WaveformBuffer", m_Data);
cmd.SetComputeTextureParam(compute, kernel, "_Source", ShaderIDs.WaveformSource);
cmd.SetComputeVectorParam(compute, "_Params", parameters);
cmd.DispatchCompute(compute, kernel, width, Mathf.CeilToInt(height / (float)m_ThreadGroupSize), 1);
cmd.ReleaseTemporaryRT(ShaderIDs.WaveformSource);
// Generate the waveform texture
var sheet = context.propertySheets.Get(context.resources.shaders.waveform);
sheet.properties.SetVector(ShaderIDs.Params, new Vector4(width, height, exposure, 0f));
sheet.properties.SetBuffer(ShaderIDs.WaveformBuffer, m_Data);
cmd.BlitFullscreenTriangle(BuiltinRenderTextureType.None, output, sheet, 0);
cmd.EndSample("Waveform");
}