Merge pull request #5959 from Calinou/gles2-blend-shapes

Document blend shapes being supported in GLES2

tutorials/rendering/gles2_gles3_differences.rst

@@ -136,7 +136,10 @@ so if exporting to mobile using GLES2 make sure to set the project setting
 Blend shapes
 ------------
 
-Blend shapes are not supported in GLES2.
+In GLES2, blend shapes are implemented on the CPU instead of the GPU.
+Accordingly, they may not perform as well as blend shapes in GLES3. To avoid
+performance issues when using blend shapes in GLES2, try to minimize the number
+of blend shapes that are updated each frame.
 
 Shading language
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