My opacity maps look strange!
--- This article concerns Corona Renderer 1.5. The behavior has been changed in Corona 1.6, and now the "Clip" option is off by default. ---
New "Clip" option in material settings is on by default in Corona Renderer 1.5. It greatly increases rendering performance, but it changes the way opacity maps are processed. With this option enabled, any smooth gradients or soft edges used in an opacity map will be missing, as the map will be clamped to pure black and white values only. This is useful for "cutout" materials such as leaves, grass blades, wire fences, and other objects with hard edges only. If you wish to keep smooth gradients and soft edges in your opacity map, simply disable the "Clip" option in the material editor under material settings > Opacity.
Opacity mapped materials - Corona 1.4 ("clip" option off)
Render time: 01:19
Note blurry edges and smooth gradients.
Opacity mapped materials - Corona 1.5 ("clip" option on)
Render time: 01:01
Note hard edges and no smooth gradients.