Monday, February 29, 2016

More Reflections

I can't get enough reflections in 3DWorld. They really bring life to the scenes. I recently added reflective surface support for horizontal "floor" polygons of imported models. The fragment shader enables reading from the reflection texture for fragments with z-values within the z-range of the reflection plane. Other than that change, the rest of the reflection texture creation works like I explained in my previous post.

Here is a screenshot showing the reflective marble floor from the Crytek Sponza atrium scene. You can see the reflected colored curtains and fire in the floor.

Realtime reflections on the shiny marble floor of the Crytek Sponza atrium.

I also added support for multiple reflective z-planes so that more than one floor can be reflective. The active reflective surface is selected as the one with z-value closest to the camera position from the visible surfaces below the camera. Surfaces above the camera are ignored because the system assumes only the top of the objects are reflective. Here is a screenshot showing reflections on the upper floor of the Sponza atrium with some moving dynamic light sources.

Reflections of the scene and some colored lights on the upper level of the Sponza scene.

I made the marble floor of the museum scene reflective as well. It makes the scene look much more realistic. Take a look at the way the windows look reflected from the floor.

Reflections on the marble floor of the museum scene.

Here is the museum scene shown from a different viewpoint where the dinosaur skeletons are visible.

Another view of the museum scene showing the reflective floor.

I'm currently working on cube map reflections for small placed reflective objects such as the golden dragon in the office building scene. Cube map reflections are more difficult than planar reflections because they need to be rendered from all six sides of a cube rather than a single reflection plane. It's probably too slow to generate all six cube face images each frame for large scenes, so other tricks need to be played. For example, if the scene is static (no moving objects), the reflection images can be rendered once as preprocessing rather than per-frame. I'll make another post if/when I get this working correctly.

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