Computer Graphics

Environment mapping

Practice session 10

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Reflection

http://www.jholko.com/data/photos/641_1polar_bear_reflection_svalbard.jpg

In game screens

http://media1.gameinformer.com/imagefeed/screenshots/DeusExHumanRevolution/DeusExHumanRevolutionMedia/dx_hr_screenshot_hacking2.jpg

Other kind of in game screens

http://oyster.ignimgs.com/wordpress/stg.ign.com/2014/03/portal.jpg

User interfaces

Game engines

• Unity 3D - Render texture
• Unreal 4 - Render to texture toolset

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How-to

1. Render the scene to texture.
2. Render the scene again and blend the rendered material colors from lighting calculation together with colors sampled from texture.

Javascript exercise

A slight variation (c++ exercise)

1. Render the scene into framebuffer
2. Render the scene into framebuffer again and use glBlendFunc to blend with colors already in the framebuffer.

A slight variation - slightly less abstract

1. Create a stencil in stencil buffer for the reflective object.

Stencil buffer

In the simplest case, the stencil buffer is used to limit the area of rendering(stencling).

A slight variation - slightly less abstract

Except since we are only writing to stencil buffer.

A slight variation - slightly less abstract

2. Draw reflected area

Mirroring

xz plane as plane of reflection

glm::scale(model, glm::vec3(1.0, -1.0, 1.0));

http://image.tutorvista.com/cms/images/38/horizontal-and-vertical-reflection.jpg

A slight variation - slightly less abstract

3. Together with the stencil we created

A slight variation - slightly less abstract

Blend together with semi transparent floor and add rest of the scene without blending.