gl-state
Version:
Saves WebGL context state
344 lines (321 loc) • 9.98 kB
JavaScript
"use strict"
module.exports = createGLStateStack
var uniq = require("uniq")
function createGLStateStack(gl, variables) {
//By default SAVE EVERYTHING
if(!variables) {
variables = [
gl.ACTIVE_TEXTURE,
gl.ARRAY_BUFFER_BINDING,
gl.BLEND,
gl.BLEND_COLOR,
gl.BLEND_SRC_ALPHA,
gl.BLEND_SRC_RGB,
gl.BLEND_DST_ALPHA,
gl.BLEND_DST_RGB,
gl.BLEND_EQUATION_ALPHA,
gl.BLEND_EQUATION_RGB,
gl.COLOR_WRITEMASK,
gl.COLOR_CLEAR_VALUE,
gl.CULL_FACE,
gl.CULL_FACE_MODE,
gl.CURRENT_PROGRAM,
gl.DEPTH_CLEAR_VALUE,
gl.DEPTH_FUNC,
gl.DEPTH_RANGE,
gl.DEPTH_WRITEMASK,
gl.DITHER,
gl.ELEMENT_ARRAY_BUFFER_BINDING,
gl.FRAMEBUFFER_BINDING,
gl.FRONT_FACE,
gl.GENERATE_MIPMAP_HINT,
gl.LINE_WIDTH,
gl.PACK_ALIGNMENT,
gl.POLYGON_OFFSET_FACTOR,
gl.POLYGON_OFFSET_FILL,
gl.POLYGON_OFFSET_UNITS,
gl.RENDERBUFFER_BINDING,
gl.SAMPLE_COVERAGE,
gl.SAMPLE_COVERAGE_INVERT,
gl.SAMPLE_COVERAGE_VALUE,
gl.SCISSOR_BOX,
gl.SCISSOR_TEST,
gl.STENCIL_BACK_FAIL,
gl.STENCIL_BACK_FUNC,
gl.STENCIL_BACK_PASS_DEPTH_FAIL,
gl.STENCIL_BACK_PASS_DEPTH_PASS,
gl.STENCIL_BACK_REF,
gl.STENCIL_BACK_VALUE_MASK,
gl.STENCIL_BACK_WRITEMASK,
gl.STENCIL_CLEAR_VALUE,
gl.STENCIL_FAIL,
gl.STENCIL_FUNC,
gl.STENCIL_PASS_DEPTH_FAIL,
gl.STENCIL_PASS_DEPTH_PASS,
gl.STENCIL_REF,
gl.STENCIL_TEST,
gl.STENCIL_VALUE_MASK,
gl.STENCIL_WRITEMASK,
gl.TEXTURE,
gl.UNPACK_ALIGNMENT,
gl.UNPACK_COLORSPACE_CONVERSION_WEBGL,
gl.UNPACK_FLIP_Y_WEBGL,
gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL,
gl.VIEWPORT
]
}
var ctorBody = [
"'use strict'\nfunction StateStack(gl){this.gl=gl;"
]
var pushBody = [
"proto.push=function(){var gl=this.gl;"
]
var popBody = [
"proto.pop=function(){var gl=this.gl;"
]
//Compute a collection of state variables
var nvariables = variables.slice()
nvariables.sort(function(a,b) {
return a-b
})
uniq(nvariables, undefined, true)
//Check if texture state needs to be saved
var textureTypes = [gl.TEXTURE,
gl.TEXTURE_2D,
gl.TEXTURE_CUBE_MAP,
gl.TEXTURE_BINDING_2D,
gl.TEXTURE_BINDING_CUBE_MAP]
if(textureTypes.some(function(v) {
return nvariables.indexOf(v) >= 0
})) {
//Generate code for saving texture state
var numTextures = gl.getParameter(gl.MAX_TEXTURE_IMAGE_UNITS)
ctorBody.push("this.textures=[];")
//Generate save state for textures
pushBody.push("var curTex=gl.getParameter(", gl.ACTIVE_TEXTURE, "),texState=new Array(",numTextures,");")
for(var i=0; i<numTextures; ++i) {
pushBody.push("gl.activeTexture(", gl.TEXTURE0+i, ");texState[",i,"]=[gl.getParameter(",
gl.TEXTURE_BINDING_2D, "),gl.getParameter(",
gl.TEXTURE_BINDING_CUBE_MAP, ")];")
}
pushBody.push("this.textures.push(texState);gl.activeTexture(curTex);")
//Generate restore state for textures
popBody.push("var texState=this.textures.pop();")
var restoreActive = nvariables.indexOf(gl.ACTIVE_TEXTURE) < 0
if(restoreActive) {
popBody.push("var curTex=gl.getParameter(", gl.ACTIVE_TEXTURE, ");")
}
for(var i=0; i<numTextures; ++i) {
popBody.push(
"gl.activeTexture(", gl.TEXTURE0+i, ");",
"gl.bindTexture(", gl.TEXTURE_2D, ",texState[", i, "][0]);",
"gl.bindTexture(", gl.TEXTURE_CUBE_MAP, ",texState[", i, "][1]);")
}
if(restoreActive) {
popBody.push("gl.activeTexture(curTex);")
}
}
//Multiparameter state functions
var specialVars = {
blendEquationSeparate: [
gl.BLEND_EQUATION_ALPHA,
gl.BLEND_EQUATION_RGB
],
blendFuncSeparate: [
gl.BLEND_SRC_RGB,
gl.BLEND_DST_RGB,
gl.BLEND_SRC_ALPHA,
gl.BLEND_DST_ALPHA
],
sampleCoverage: [
gl.SAMPLE_COVERAGE_INVERT,
gl.SAMPLE_COVERAGE_VALUE
],
polygonOffset: [
gl.POLYGON_OFFSET_FACTOR,
gl.POLYGON_OFFSET_UNITS
],
stencilFuncSeparate_FRONT: [
gl.STENCIL_FUNC,
gl.STENCIL_REF,
gl.STENCIL_VALUE_MASK
],
stencilFuncSeparate_BACK: [
gl.STENCIL_BACK_FUNC,
gl.STENCIL_BACK_REF,
gl.STENCIL_BACK_VALUE_MASK
],
stencilOpSeparate_FRONT: [
gl.STENCIL_FAIL,
gl.STENCIL_PASS_DEPTH_FAIL,
gl.STENCIL_PASS_DEPTH_PASS
],
stencilOpSeparate_BACK: [
gl.STENCIL_BACK_FAIL,
gl.STENCIL_BACK_PASS_DEPTH_FAIL,
gl.STENCIL_BACK_PASS_DEPTH_PASS
]
}
//Decorate all multiparameter fields
for(var id in specialVars) {
var params = specialVars[id]
var variables = []
var snippets = []
for(var i=0; i<params.length; ++i) {
var name = "v" + params[i]
var snip = [name, "=gl.getParameter(", params[i], ");"].join("")
variables.push(name)
snippets.push(snip)
}
specialVars[id] = {
present: false,
variables: variables,
snippets: snippets,
parameters: params
}
}
main_loop:
for(var i=0; i<nvariables.length; ++i) {
var type = nvariables[i]
//Textures handled separately
if(textureTypes.indexOf(type) >= 0) {
continue
}
var stateStack = "this[" + type + "]"
ctorBody.push(stateStack, "=[];")
//Generate save code
switch(type) {
case gl.SAMPLE_COVERAGE:
//HACK: This is broken in the webgl specification
pushBody.push(stateStack, ".push(gl.isEnabled(", gl.SAMPLE_COVERAGE, "));")
break
default:
pushBody.push(stateStack, ".push(gl.getParameter(", type, "));")
break
}
//Generate restore code
var sv = stateStack + ".pop()"
switch(type) {
case gl.ACTIVE_TEXTURE:
popBody.push("gl.activeTexture(", sv, ");")
break
case gl.ARRAY_BUFFER_BINDING:
popBody.push("gl.bindBuffer(", gl.ARRAY_BUFFER, ",", sv, ");")
break
case gl.BLEND_COLOR:
popBody.push("var c=", sv, ";gl.blendColor(c[0], c[1], c[2], c[3]);")
break
case gl.COLOR_CLEAR_VALUE:
popBody.push("var c=", sv, ";gl.clearColor(c[0], c[1], c[2], c[3]);")
break
case gl.COLOR_WRITEMASK:
popBody.push("var c=", sv, ";gl.colorMask(c[0], c[1], c[2], c[3]);")
break
case gl.CULL_FACE_MODE:
popBody.push("gl.cullFace(", sv, ");")
break
case gl.CURRENT_PROGRAM:
popBody.push("gl.useProgram(", sv, ");")
break
case gl.DEPTH_CLEAR_VALUE:
popBody.push("gl.clearDepth(", sv, ");")
break
case gl.DEPTH_FUNC:
popBody.push("gl.depthFunc(", sv, ");")
break
case gl.DEPTH_RANGE:
popBody.push("var z=", sv, ";gl.depthRange(z[0], z[1]);")
break
case gl.DEPTH_WRITEMASK:
popBody.push("gl.depthMask(", sv, ");")
break
case gl.ELEMENT_ARRAY_BUFFER_BINDING:
popBody.push("gl.bindBuffer(", gl.ELEMENT_ARRAY_BUFFER, ",", sv, ");")
break
case gl.FRAMEBUFFER_BINDING:
popBody.push("gl.bindFramebuffer(", gl.FRAMEBUFFER, ",", sv, ");")
break
case gl.FRONT_FACE:
popBody.push("gl.frontFace(", sv, ");")
break
case gl.LINE_WIDTH:
popBody.push("gl.lineWidth(", sv, ");")
break
case gl.RENDERBUFFER_BINDING:
popBody.push("gl.bindRenderbuffer(", gl.RENDERBUFFER, ",", sv, ");")
break
case gl.SCISSOR_BOX:
popBody.push("var c=", sv, ";gl.scissor(c[0],c[1],c[2],c[3]);")
break
case gl.STENCIL_WRITEMASK:
popBody.push("gl.stencilMaskSeparate(", gl.FRONT, ",", sv, ");")
break
case gl.STENCIL_BACK_WRITEMASK:
popBody.push("gl.stencilMaskSeparate(", gl.BACK, ",", sv, ");")
break
case gl.STENCIL_CLEAR_VALUE:
popBody.push("gl.clearStencil(", sv, ");")
break
case gl.VIEWPORT:
popBody.push("var c=", sv, ";gl.viewport(c[0],c[1],c[2],c[3]);")
break
//Pixel storage
case gl.PACK_ALIGNMENT:
case gl.UNPACK_ALIGNMENT:
case gl.UNPACK_COLORSPACE_CONVERSION_WEBGL:
case gl.UNPACK_FLIP_Y_WEBGL:
case gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL:
popBody.push("gl.pixelStorei(", type, ",", sv, ");")
break
//Flags
case gl.BLEND:
case gl.CULL_FACE:
case gl.DEPTH_TEST:
case gl.DITHER:
case gl.POLYGON_OFFSET_FILL:
case gl.SAMPLE_COVERAGE:
case gl.SCISSOR_TEST:
case gl.STENCIL_TEST:
popBody.push("if(", sv, "){gl.enable(", type, ")}else{gl.disable(", type, ")}")
break
//Hints
case gl.GENERATE_MIPMAP_HINT:
popBody.push("gl.hint(", type, ",", sv, ");")
break
default:
//Check if special variable present
for(var id in specialVars) {
var special = specialVars[id]
var index = special.parameters.indexOf(type)
if(index < 0) {
continue
}
special.present = true
special.snippets[index] = "var " + special.variables[index] + "=" + sv + ";"
continue main_loop
}
throw new Error("gl-state: Error, unknown state parameter " + type)
}
}
//Handle multiparameter functions
for(var id in specialVars) {
var data = specialVars[id]
if(data.present) {
popBody.push.apply(popBody, data.snippets)
var parts = id.split("_")
if(parts.length === 1) {
popBody.push("gl.", parts[0], "(", data.variables.join(","), ");")
} else {
popBody.push("gl.", parts[0], "(gl.", parts[1], ",", data.variables.join(","), ");")
}
}
}
//Compile procedure
var code = [ctorBody.join(""),
"};var proto=StateStack.prototype;",
pushBody.join(""), "};",
popBody.join(""), "};",
"return new StateStack(gl);"].join("")
var proc = new Function("gl", code)
return proc(gl)
}