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skybox.js
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skybox.js
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/**
* skybox.js
*
* @fileoverview Manages buffers, arrays, and other data related to skybox.
* @author Po-Han Huang <phuang17@illinois.edu>
*/
/** Identification prefix for skybox shader. */
var SKYBOX_PREFIX = "skybox";
/** Size of skybox */
var SKYBOX_SIZE = 3.0;
/** GL buffers for skybox. */
var skyboxPositionBuffer;
var skyboxIndexBuffer;
/** Data array for skybox. */
var skyboxPositionArray = [];
var skyboxIndexArray = [];
/** Shader program for skybox. */
var skyboxShaderProgram;
/** Variable locations in shader program. */
var skyboxLocations = {};
/** Environment texture for skybox. */
var skyboxTexture;
/** Initialization of skybox.js */
function skyboxInit(){
/** Register shaders, draw calls, animate calls. */
shaderPrefix.push(SKYBOX_PREFIX);
shaderInit[SKYBOX_PREFIX] = skyboxShaderInit;
bufferInit[SKYBOX_PREFIX] = skyboxBufferInit;
drawFunctions[SKYBOX_PREFIX] = skyboxDraw;
animateFunctions[SKYBOX_PREFIX] = skyboxAnimate;
/** Initialize skybox and cube map. */
skyboxGenerateShape();
setupCubeMap();
}
/** Initialize skybox's shader programs and variable locations. */
function skyboxShaderInit(){
skyboxShaderProgram = shaderPrograms[SKYBOX_PREFIX];
/** Attributes */
skyboxLocations["aVertexPosition"] = gl.getAttribLocation(skyboxShaderProgram, "aVertexPosition");
/** Uniforms */
skyboxLocations["uPMatrix"] = gl.getUniformLocation(skyboxShaderProgram, "uPMatrix");
skyboxLocations["uMVMatrix"] = gl.getUniformLocation(skyboxShaderProgram, "uMVMatrix");
skyboxLocations["uEnv"] = gl.getUniformLocation(skyboxShaderProgram, "uEnv");
}
/** Initialize skybox's buffer. */
function skyboxBufferInit(){
/** Create buffers. */
skyboxPositionBuffer = gl.createBuffer();
skyboxIndexBuffer = gl.createBuffer();
/** Bind buffers. */
skyboxPositionBuffer.itemSize = 3;
skyboxPositionBuffer.numOfItems = skyboxPositionArray.length / skyboxPositionBuffer.itemSize;
gl.bindBuffer(gl.ARRAY_BUFFER, skyboxPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(skyboxPositionArray), gl.STATIC_DRAW);
skyboxIndexBuffer.itemSize = 1;
skyboxIndexBuffer.numOfItems = skyboxIndexArray.length / skyboxIndexBuffer.itemSize;
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, skyboxIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Int16Array(skyboxIndexArray), gl.STATIC_DRAW);
}
/** Airplane draw call */
function skyboxDraw(){
/** Setup variables. */
gl.useProgram(skyboxShaderProgram);
gl.bindBuffer(gl.ARRAY_BUFFER, skyboxPositionBuffer);
gl.enableVertexAttribArray(skyboxLocations["aVertexPosition"]);
gl.vertexAttribPointer(skyboxLocations["aVertexPosition"], skyboxPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, skyboxIndexBuffer);
gl.uniformMatrix4fv(skyboxLocations["uPMatrix"], false, pMatrix);
gl.uniformMatrix4fv(skyboxLocations["uMVMatrix"], false, mvMatrix);
gl.uniform1i(skyboxLocations["uEnv"], 0);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, skyboxTexture);
/** Draw! */
gl.drawElements(gl.TRIANGLES, skyboxIndexBuffer.numOfItems, gl.UNSIGNED_SHORT, 0);
/** Destructor */
gl.disableVertexAttribArray(skyboxLocations["aVertexPosition"]);
}
/**
* Airplane animate call
*
* @param {float} lapse timelapse since last frame in sec
*/
function skyboxAnimate(){
}
/** Generate skybox model. */
function skyboxGenerateShape(){
/** Boundaries of skybox. */
var sizes = [-SKYBOX_SIZE, SKYBOX_SIZE];
/** Generate six faces. */
for(var z in sizes){
for(var y in sizes){
for(var x in sizes){
skyboxPositionArray.push(sizes[x]);
skyboxPositionArray.push(sizes[y]);
skyboxPositionArray.push(sizes[z]);
}
}
}
/** Generate indices. */
skyboxIndexArray = [
0,1,2, 2,1,3,
4,5,6, 6,5,7,
0,4,1, 4,5,1,
2,6,3, 6,7,3,
0,2,4, 2,6,4,
1,3,5, 3,7,5
];
}
/** Setup cube map. */
function setupCubeMap() {
/** Set up texture. */
skyboxTexture = gl.createTexture();
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, skyboxTexture);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
/** Setup sixe faces. */
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_POSITIVE_X, skyboxTexture, posx);
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_NEGATIVE_X, skyboxTexture, negx);
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_POSITIVE_Y, skyboxTexture, posy);
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_NEGATIVE_Y, skyboxTexture, negy);
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_POSITIVE_Z, skyboxTexture, posz);
loadCubeMapFace(gl, gl.TEXTURE_CUBE_MAP_NEGATIVE_Z, skyboxTexture, negz, function(){
/** Generate mipmap after all faces are loaded. */
gl.generateMipmap(gl.TEXTURE_CUBE_MAP);
});
}
/**
* Load one face of cube map.
*
* @param {gl} gl instance
* @param {target} target face to load
* @param {texture} texture instance
* @param {url} url of image
* @param {callback} callback funcion
*/
function loadCubeMapFace(gl, target, texture, url, callback){
var img = new Image();
img.src = url;
img.onload = function (){
gl.activeTexture(gl.TEXTURE0);
gl.texImage2D(target, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, img);
if(callback){
callback();
}
}
}