Render accumulation

Author: jkulhanek

diff_gaussian_rasterization/__init__.py

@@ -95,10 +95,24 @@ def forward(
         ctx.raster_settings = raster_settings
         ctx.num_rendered = num_rendered
         ctx.save_for_backward(colors_precomp, means3D, scales, rotations, cov3Ds_precomp, radii, sh, geomBuffer, binningBuffer, imgBuffer)
-        return color, radii
+
+        accumulation = None
+        if raster_settings.return_accumulation:
+            alignment = 128
+            offset = (alignment - imgBuffer.data_ptr()) % alignment
+            total_size = raster_settings.image_height * raster_settings.image_width * 4
+            accumulation = (
+                imgBuffer[offset: offset + total_size]
+                .view(torch.float32)
+                .clone()
+                .mul_(-1)
+                .add_(1)
+                .view((raster_settings.image_height, raster_settings.image_width))
+            )
+        return color, radii, accumulation
 
     @staticmethod
-    def backward(ctx, grad_out_color, _):
+    def backward(ctx, grad_out_color, _1, _2):
 
         # Restore necessary values from context
         num_rendered = ctx.num_rendered
@@ -167,6 +181,7 @@ class GaussianRasterizationSettings(NamedTuple):
     campos : torch.Tensor
     prefiltered : bool
     debug : bool
+    return_accumulation : bool
 
 class GaussianRasterizer(nn.Module):
     def __init__(self, raster_settings):