Blending modes

Defines blending mode.

Rendering mode :

0 - normal
1 - additive

Diffusion target :

0 - modulation (out = in * color)
2 - addition   (out = in + color)
4 - smooth addition (out = in + color - in * color)
6 - 2x modulation (out = in * color * 2)
8 - signed addition (out = in + color - 0.5)

Special :

32 - disable alpha blending.

Combine flags by OR-ing "|" or adding.