/**
* @module Buffers
*/
define(['gl', 'shaders', 'lighting'], function (gl, shaderProgram, lighting) {
/**
* @class Buffers
*/
return {
/**
* Initialises the buffers.
* @method initBuffers
* @param {AstronomicalObject} obj The object for which we're initialising buffers.
*/
initBuffers: function (obj) {
if (obj.spherical) {
this.initSphericalBuffers(obj);
} else {
this.initCuboidalBuffers(obj);
}
},
/**
* Draws the necessary elements of the object onto the canvas.
* @method drawElements
* @param {AstronomicalObject} obj The object which needs to be drawn.
*/
drawElements: function (obj) {
if (obj.spherical) {
this.drawSphericalElements(obj);
} else {
this.drawCuboidalElements(obj);
}
},
/**
* Called by initBuffers(), this initialises the buffers for spherical objects, e.g. planets, the moon, the Sun.
* @method initSphericalBuffers
* @param {AstronomicalObject} obj The spherical object we're initialising buffers for.
*/
initSphericalBuffers: function (obj) {
var radius = obj.radius;
var latitudeBands = 30;
var longitudeBands = 30;
var vertexPositionData = [];
var normalData = [];
var textureCoordData = [];
for (var latNumber = 0; latNumber <= latitudeBands; latNumber++) {
var theta = latNumber * Math.PI / latitudeBands;
var sinTheta = Math.sin(theta);
var cosTheta = Math.cos(theta);
for (var longNumber = 0; longNumber <= longitudeBands; longNumber++) {
var phi = longNumber * 2 * Math.PI / longitudeBands;
var sinPhi = Math.sin(phi);
var cosPhi = Math.cos(phi);
var x = cosPhi * sinTheta;
var y = cosTheta;
var z = sinPhi * sinTheta;
var u = 1 - (longNumber / longitudeBands);
var v = 1 - (latNumber / latitudeBands);
normalData.push(x);
normalData.push(y);
normalData.push(z);
textureCoordData.push(u);
textureCoordData.push(v);
vertexPositionData.push(radius * x);
vertexPositionData.push(radius * y);
vertexPositionData.push(radius * z);
}
}
var indexData = this._getIndexData(latitudeBands, longitudeBands);
obj.vertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(normalData), gl.STATIC_DRAW);
obj.vertexNormalBuffer.itemSize = 3;
obj.vertexNormalBuffer.numItems = normalData.length / 3;
obj.vertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexTextureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoordData), gl.STATIC_DRAW);
obj.vertexTextureCoordBuffer.itemSize = 2;
obj.vertexTextureCoordBuffer.numItems = textureCoordData.length / 2;
obj.vertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexPositionData), gl.STATIC_DRAW);
obj.vertexPositionBuffer.itemSize = 3;
obj.vertexPositionBuffer.numItems = vertexPositionData.length / 3;
obj.vertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.vertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indexData), gl.STATIC_DRAW);
obj.vertexIndexBuffer.itemSize = 1;
obj.vertexIndexBuffer.numItems = indexData.length;
},
/**
* A private method called by initSphericalBuffers, which calculates index data used by gl.ELEMENT_ARRAY_BUFFER.
* @method _getIndexData
* @param {int} latitudeBands Latitude bands of the sphere
* @param {int} longitudeBands Longitude bands of the sphere
* @return {array} Index data.
*/
_getIndexData: function (latitudeBands, longitudeBands) {
var indexData = [];
for (var latNumber = 0; latNumber < latitudeBands; latNumber++) {
for (var longNumber = 0; longNumber < longitudeBands; longNumber++) {
var first = (latNumber * (longitudeBands + 1)) + longNumber;
var second = first + longitudeBands + 1;
indexData.push(first);
indexData.push(second);
indexData.push(first + 1);
indexData.push(second);
indexData.push(second + 1);
indexData.push(first + 1);
}
}
return indexData;
},
/**
* Called by initBuffers(), this initialises the buffers for cuboidal objects, e.g. Saturn's rings
* @method initCuboidalBuffers
* @param {AstronomicalObject} obj The cuboidal object we're initialising buffers for.
*/
initCuboidalBuffers: function (obj) {
var width = obj.radius,
depth = width,
height = 0.1;
obj.cubeVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, obj.cubeVertexPositionBuffer);
var vertices = [
// Front face
-width, -height, depth,
width, -height, depth,
width, height, depth,
-width, height, depth,
// Back face
-width, -height, -depth,
-width, height, -depth,
width, height, -depth,
width, -height, -depth,
// Top face
-width, height, -depth,
-width, height, depth,
width, height, depth,
width, height, -depth,
// Bottom face
-width, -height, -depth,
width, -height, -depth,
width, -height, depth,
-width, -height, depth,
// Right face
width, -height, -depth,
width, height, -depth,
width, height, depth,
width, -height, depth,
// Left face
-width, -height, -depth,
-width, -height, depth,
-width, height, depth,
-width, height, -depth
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
obj.cubeVertexPositionBuffer.itemSize = 3;
obj.cubeVertexPositionBuffer.numItems = 24;
obj.cubeVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, obj.cubeVertexTextureCoordBuffer);
var textureCoords = [
// Front face
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Back face
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
// Top face
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
// Bottom face
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
1.0, 0.0,
// Right face
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
0.0, 0.0,
// Left face
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0
];
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
obj.cubeVertexTextureCoordBuffer.itemSize = 2;
obj.cubeVertexTextureCoordBuffer.numItems = 24;
obj.cubeVertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.cubeVertexIndexBuffer);
var cubeVertexIndices = [
0, 1, 2, 0, 2, 3, // Front face
4, 5, 6, 4, 6, 7, // Back face
8, 9, 10, 8, 10, 11, // Top face
12, 13, 14, 12, 14, 15, // Bottom face
16, 17, 18, 16, 18, 19, // Right face
20, 21, 22, 20, 22, 23 // Left face
];
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
obj.cubeVertexIndexBuffer.itemSize = 1;
obj.cubeVertexIndexBuffer.numItems = 36;
},
/**
* Called by drawElements(), this draws the elements that comprise spherical objects.
* @method drawSphericalElements
* @param {AstronomicalObject} obj The spherical object we're drawing
*/
drawSphericalElements: function (obj) {
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, obj.vertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, obj.vertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, obj.vertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute, obj.vertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);
// transparency
gl.disable(gl.BLEND);
gl.enable(gl.DEPTH_TEST);
gl.uniform1f(shaderProgram.alphaUniform, 1.0);
gl.uniform1f(shaderProgram.materialShininessUniform, lighting.getShininess());
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.vertexIndexBuffer);
gl.drawElements(gl.TRIANGLES, obj.vertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
},
/**
* Called by drawElements(), this draws the elements that comprise cuboidal objects.
* @method drawCuboidalElements
* @param {AstronomicalObject} obj The cuboidal object we're drawing
*/
drawCuboidalElements: function (obj) {
gl.bindBuffer(gl.ARRAY_BUFFER, obj.cubeVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, obj.cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, obj.cubeVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, obj.cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
// transparency
gl.blendFunc(gl.SRC_ALPHA, gl.ONE);
gl.enable(gl.BLEND);
gl.enable(gl.DEPTH_TEST);
gl.uniform1f(shaderProgram.alphaUniform, 1.0);
gl.uniform1f(shaderProgram.materialShininessUniform, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, obj.cubeVertexIndexBuffer);
gl.drawElements(gl.TRIANGLES, obj.cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
}
};
});
