Frame buffer object wrapper for WebGL
npm install gl-fbogl-fbo
======
WebGL framebuffer object wrapper
Try this in your browser if you have WebGL
``javascript
var shell = require("gl-now")()
var createFBO = require("gl-fbo")
var glslify = require("glslify")
var ndarray = require("ndarray")
var fill = require("ndarray-fill")
var fillScreen = require("a-big-triangle")
var createUpdateShader = glslify({
vertex: "\
attribute vec2 position;\
varying vec2 uv;\
void main() {\
gl_Position = vec4(position,0.0,1.0);\
uv = 0.5 * (position+1.0);\
}",
fragment: "\
precision mediump float;\
uniform sampler2D buffer;\
uniform vec2 dims;\
varying vec2 uv;\
void main() {\
float n = 0.0;\
for(int dx=-1; dx<=1; ++dx)\
for(int dy=-1; dy<=1; ++dy) {\
n += texture2D(buffer, uv+vec2(dx,dy)/dims).r;\
}\
float s = texture2D(buffer, uv).r;\
if(n > 3.0+s || n < 3.0) {\
gl_FragColor = vec4(0,0,0,1);\
} else {\
gl_FragColor = vec4(1,1,1,1);\
}\
}",
inline: true
})
var createDrawShader = glslify({
vertex: "\
attribute vec2 position;\
varying vec2 uv;\
void main() {\
gl_Position = vec4(position,0.0,1.0);\
uv = 0.5 * (position+1.0);\
}",
fragment: "\
precision mediump float;\
uniform sampler2D buffer;\
varying vec2 uv;\
void main() {\
gl_FragColor = texture2D(buffer, uv);\
}",
inline: true
})
var state, updateShader, drawShader, current = 0
shell.on("gl-init", function() {
var gl = shell.gl
//Turn off depth test
gl.disable(gl.DEPTH_TEST)
//Initialize shaders
updateShader = createUpdateShader(gl)
drawShader = createDrawShader(gl)
//Allocate buffers
state = [ createFBO(gl, [512, 512]), createFBO(gl, [512, 512]) ]
//Initialize state buffer
var initial_conditions = ndarray(new Uint8Array(5125124), [512, 512, 4])
fill(initial_conditions, function(x,y,c) {
if(c === 3) {
return 255
}
return Math.random() > 0.9 ? 255 : 0
})
state[0].color[0].setPixels(initial_conditions)
//Set up vertex pointers
drawShader.attributes.position.location = updateShader.attributes.position.location = 0
})
shell.on("tick", function() {
var gl = shell.gl
var prevState = state[current]
var curState = state[current ^= 1]
//Switch to state fbo
curState.bind()
//Run update shader
updateShader.bind()
updateShader.uniforms.buffer = prevState.color[0].bind()
updateShader.uniforms.dims = prevState.shape
fillScreen(gl)
})
shell.on("gl-render", function(t) {
var gl = shell.gl
//Render contents of buffer to screen
drawShader.bind()
drawShader.uniforms.buffer = state[current].color[0].bind()
fillScreen(gl)
})
`
Result:

Install using npm:
npm install gl-fbo
* gl is a handle to a WebGL contextshape
* is a length 2 array encoding the [width, height] of the frame bufferoptions
* is an object containing the following optional properties:
+ options.preferFloat Upgrade to floating point if available, otherwise fallback to 8bit. (default false)options.float
+ Use floating point textures (default false)options.color
+ The number of color buffers to create (default 1)options.depth
+ If fbo has a depth buffer (default: true)options.stencil
+ If fbo has a stencil buffer (default: false)
`javascript`
//Bind the drawing buffer
gl.bindFramebuffer(gl.FRAMEBUFFER, null)
`javascript`
fbo.shape = [ newWidth, newHeight ]
objects representing the buffers. . If not present, is null`.Credits
=======
(c) 2013-2014 Mikola Lysenko. MIT License