Fix T66100: WorkBench Banding Issues

Color banding issues can appear, as result of the 8 bitdepth RGBA that
is used in the viewport.

This change will use `GPU_RGBA16F` for final renderings and for drawing textures. This
allows displaying HDRI textures. Vertex Colors uses `GPU_RGBA16` to resolve
color banding issues. All other modes use `GPU_RGBA8` to reduce
bandwidth and gpu memory.

Reviewed By: fclem, brecht

Differential Revision: https://developer.blender.org/D5179

1 files changed, 24 insertions, 0 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_private.h b/source/blender/draw/engines/workbench/workbench_private.h
index 17144c4dc10..cb9a97878e2 100644
--- a/source/blender/draw/engines/workbench/workbench_private.h
+++ b/source/blender/draw/engines/workbench/workbench_private.h
@@ -381,6 +381,30 @@ BLI_INLINE bool workbench_is_matdata_pass_enabled(WORKBENCH_PrivateData *wpd)
          workbench_is_in_texture_paint_mode();
 }
 
+/**
+ * Get the default texture format to be used by the color and history buffers.
+ *
+ * Use GPU_RGBA16F for final renderings and for drawing textures. This
+ * allows displaying HDRI textures. Vertex Colors uses GPU_RGBA16 to resolve
+ * color banding issues (T66100). All other modes use GPU_RGBA8 to reduce
+ * bandwidth and gpu memory.
+ */
+BLI_INLINE const eGPUTextureFormat workbench_color_texture_format(const WORKBENCH_PrivateData *wpd)
+{
+  eGPUTextureFormat result;
+  if (DRW_state_is_image_render() || workbench_is_in_texture_paint_mode() ||
+      TEXTURE_DRAWING_ENABLED(wpd)) {
+    result = GPU_RGBA16F;
+  }
+  else if (VERTEX_COLORS_ENABLED(wpd)) {
+    result = GPU_RGBA16;
+  }
+  else {
+    result = GPU_RGBA8;
+  }
+  return result;
+}
+
 /* workbench_deferred.c */
 void workbench_deferred_engine_init(WORKBENCH_Data *vedata);
 void workbench_deferred_engine_free(void);