Uploaded September 2016 | Updated September 2026, 1 week ago

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After playing mobile racing game "Need for speed no limits", I decided to create this demo to test if this kind of graphics is practical using Unity.The main focus of this demo is realtime cubemap reflection on mobile, which appears on the car & road's wet surface.The method I used allows both car & road sample the same cubemap render result, although the reflection on the car is not correct(only the road's reflection is correct), but I found that it is faster & still acceptable in a racing game

This demo runs @ stable 30FPS on HTC desire 805(GPU=Adreno 305, opengles3, 720p),

if using a lower resolution framebuffer & lower resolution realtime cubemap, it can run @ stable 60FPS.

One important optimization is pushing world space reflection vertor's calculation from fragment shader to vertex shader, it requires pre-tessellated mesh(road & car) to calculate acceptable reflection, but since the road cover large portion of the screen, the time saved from fragment shader's reflection vector calculation is huge.

Also cubemap rendering using a lower resolution can increase performance a lot.

see how the reflection probe(realtime cube map)'s position affect the final reflection result:
imgur.com/l4AGakl