Fix T76558: Decreasing Viewport Anti-Aliasing Samples Makes Scene Whiter

When setting the Viewport Anti-Aliasing samples in the user preferences
to a lower sample count the anti-aliasing was not reset. This lead to
incorrect result as the accum buffer would still hold the values of the
larger sample count.

This fix resets the TAA when the sample count is changed.

Reviewed By: Clément Foucault

Differential Revision: https://developer.blender.org/D7728

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_effect_antialiasing.c b/source/blender/draw/engines/workbench/workbench_effect_antialiasing.c
index 5c8730ac8f9..d2bd653a656 100644
--- a/source/blender/draw/engines/workbench/workbench_effect_antialiasing.c
+++ b/source/blender/draw/engines/workbench/workbench_effect_antialiasing.c
@@ -176,6 +176,14 @@ void workbench_antialiasing_engine_init(WORKBENCH_Data *vedata)
     }
   }
 
+  /* Reset the TAA when we have already draw a sample, but the sample count differs from previous
+   * time. This removes render artifacts when the viewport anti-aliasing in the user preferences is
+   * set to a lower value. */
+  if (wpd->taa_sample_len != wpd->taa_sample_len_previous) {
+    wpd->taa_sample = 0;
+    wpd->taa_sample_len_previous = wpd->taa_sample_len;
+  }
+
   if (wpd->view_updated) {
     wpd->taa_sample = 0;
     wpd->view_updated = false;