Bloom Effect

A bloom effect makes the bright area of image has a 'hazy' around.  To achieve bloom effect, you need:

1. Bright-pass image to produce the bright pattern.

use the bright_pass.sha shader to filter out bright area to a texture ( 256 x 256 size is suitable).

 

2. Blurring the bright pattern and down scale it.

use the blur_4x_tex.sha or blur_2x2.sha shader to blurring & down-scale bright pattern to a small texture (64 x 64 size is suitable).
A example flow path:
    blur_2x2_256.sha ( output to 128 x 128 image ) blur_2x2_128.sha ( output to 64 x 64 image ) blur_2x2_64.sha ( output to 64 x 64 image ) more blurring if needed...

3. Combine the original scene image and the final bright pattern

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use the present_bloom.sha shader cover bright pattern to the original scene image.