1. Modulated shadows don’t work without Mobile HDR.
Mobile HDR needs to be enabled for modulated shadowing to work and also requires a stationary directional light. It will not work with other mobilities.
2. When the same directional light is set to “Static” (and lighting is built), only the static cylinder casts shadows and the moving one does not, in both the viewport and Mobile PIE
This is 100% expected behavior when using static lighting. Shadows cannot be cast since only precomputed lighting has been used.
3. Modulated Shadows works for movable but not static actors. However, in the Mobile PIE, no red shadow is shown on the moving cylinder, but a black shadow shows on the static one.
Modulated Shadows are only expected to work for movable actors. It’s a cheaper dynamic shadowing method that was added a while back to get dynamic shadowing for movable actors. With some of the newer phones and chipsets releasing it’s getting closer to a possibility of implementing more dynamic shadowing options for mobile, as can be seen over the last couple of releases, like CSM shadows for Stationary Directional Light on mobile.
Looking at my test map, the black shadows for the dynamic light is expected because dynamic lights do not produce any bounce light (Global Illumination).
4. The “Shader Complexity” viewmode (shortcut ALT-8) in the Editor shows bright red for everything, while the “Shader Complexity” viewmode (shortcut F5) shows a dark maroon,
Shader complexity can be a good metric but it should be more a guideline and not taken as the strict truth of how well your shaders are performing. Also keep in mind the differences between PIE and Editor could be something as simple as a toggle has been turned off for some specific post process or option under the viewport > Show flags.
continued next post…