Making Custom GeckoLib Mobs Cast Correct Shadows Without Losing Animation

Why Shadows and Animations Fight

GeckoLib renders mobs by deforming a model through a bone hierarchy each frame. Shaderpacks that draw entity shadows often render the model a second time from the light's point of view. Without the compat mod, that second pass reads the model in its bind pose, so you get either a frozen shadow, a shadow that lags behind the animation, or a shadow that flickers as the two passes disagree.

Getting Both at Once

1. Keep entity shadows enabled in your shader settings — the compat mod exists precisely so you do not have to sacrifice them.

2. Verify the mob is actually a GeckoLib entity. Vanilla mobs and mobs from mods using vanilla model rendering are unaffected and will not benefit.

3. Watch the mob from several angles in daylight. The shadow should track the animated pose, including raised arms and tail swings, rather than staying in a T-pose.

4. If the shadow is correct but blurry, raise shadow resolution in the shader options; if it is correct but expensive, reduce shadow distance instead.

Tuning Performance

Animated shadows cost more than static ones because the model is skinned twice. On large modpacks with many GeckoLib mobs, cap the number of entities that cast shadows if your shaderpack exposes that option, and keep shadow distance modest. This preserves the visual fix while protecting your framerate in crowded areas.