一些shader相關網站

Formulas for Photoshop blending modes
講解一些Blend mode的公式
http://www.deepskycolors.com/archive/2010/04/21/formulas-for-Photoshop-blending-modes.html

Photoshop Blendmodi in GLSL
同上, 但是主要針對GLSL
http://renderingpipeline.com/2012/06/photoshop-blendmodi-glsl/

ANDROID LESSON FIVE: AN INTRODUCTION TO BLENDING
講解OpenGL中的BlendFunc的計算公式
http://www.learnopengles.com/tag/additive-blending/

GLSL : common mistakes
常見的GLSL錯誤
https://www.opengl.org/wiki/GLSL_:_common_mistakes