Igloo threw this error after shamelessly copying everything.
"Uncaught Error: ERROR: 0:2: '' : No precision specified for (float)"

Fixed by adding these lines to the start of each fragment shader

ifdef GL_ES

precision mediump float;

endif

Hello. I am trying to convert an old cellular automata simulation I wrote in Processing to WebGL. Your example here was the first/best one that I could find that made use of swapping or pingponging of textures, which is necessary for CA simulations on the GPU. I am trying to just replace your frag shader with mine.

The problem I have is that my CA is complex and requires two separate textures to hold all the information about a cell's state. I am not able to figure out your Igloo API and I know nothing about WebGL. In fact I barely remember what I did in Processing years ago. I am hoping that only a few lines of code need to be changed. I think I will ultimately need two 'front' textures and two 'back' textures or maybe I just need two uniform's like state and state2?

All the guts of my old CA are written in GLSL and at the top I have uniform sampler2D src_tex_unit0, src_tex_unit1; which is how the two textures are passed in. And I have out vec4 outState, outEnergy;, which is the corresponding output values for the shader.