GLSL reusable / shared functions, common constants (OpenGL ES 2.0)?

Question

Short:

Is it possible to define a function that each shader can use? Or should I define it for each shader?

The whole story:

I want to create a lot of shaders designed to colorize input fragments with predefined ramps (for example, http://www.thinkboxsoftware.com/storage/krakatoa-support-images/krakatoa15_kcm_densitybyage_gradientrampmap.png ).
I want to define a gradient ramp constant for each shader (an array of vec4 color samples, where the alpha value holds the position of the gradient, see Pos in the figure above)
And I need a function that can return a color swatch from a given gradient for a specific coordinate position of the texture.

Thus, the ramps must be defined as ONCE per shader , and the function must be defined all at once , which each shader can use safely.

I have algorithms, the question is about sharing functions and defining constants in GLSL.

Is it possible? Or do I need to copy a function to each shader? Is there any precompilation option?

+5

Geri May 05, '12 at 16:58

1 answer

Mārtiņš Možeiko · Accepted Answer · 2012-05-05T19:57:02+0000

You can do it the same way as in C - you declare functions in the headers and define them in a common C file.

GLSL :

, , ( SHADER1):

float getCommonValue();
void main() { gl_Color = vec4(getCommonValue(), 0, 0, 0); }

glCompileShader COMMON shader GLuint -
glLinkProgram SHADER1, glAttachShader - COMMON SHADER1. , getCommonValue .
COMMON shader GLuint sahder (SHADER1, SHADER2,...).