<!doctype html>
<head>
<title>sphere2</title>
<script src="minMatrix.js"></script>
</head>
<body>
<canvas id="canvas" width="640" height="480"></canvas>
<div id="msg"></div>
<script id="vs" type="text/x-vertex">
// 頂点シェイダー
attribute vec3 position;
attribute vec2 color;
uniform mat4 mvpMatrix;
varying vec2 vColor;
void main(void) {
vColor = color;
gl_Position = mvpMatrix * vec4(position, 1.0);
}
</script>
<script id="fs" type="text/x-fragment">
// 断片シェイダー
precision mediump float;
varying vec2 vColor;
void main(void) {
gl_FragColor = vec4(vColor, 0.0, 1.0);
}
</script>
<script>
var gl; // webgl context
var uniLocation = []; // uniform
var m = new matIV();
var mMatrix = m.identity(m.create()); // model
var pMatrix = m.identity(m.create()); // perspective
var positions;
var colors;
var indices;
var lat = 0; // 緯度
var lon = 90; // 経度
var dist = 3; // 距離
onload = function() {
gl = canvas.getContext("experimental-webgl");
var vShader = createShader("vs");
var fShader = createShader("fs");
var program = createProgram(vShader, fShader);
sphere(1, 32);
setAttribute(program, "position", positions, 3);
setAttribute(program, "color", colors, 2);
var ibo = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, ibo);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Int16Array(indices), gl.STATIC_DRAW);
gl.enable(gl.CULL_FACE);
gl.frontFace(gl.CW);
gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
uniLocation[0] = gl.getUniformLocation(program, "mvpMatrix");
m.perspective(45, canvas.width / canvas.height, 0.1, 10, pMatrix);
draw();
// イベント
var px, py;
var drag = false;
canvas.onmousedown = function(e) {
drag = true;
};
canvas.onmouseup = function(e) {
drag = false;
};
canvas.onmousemove = function(e) {
if (drag) {
lat = Math.min(Math.max(lat + (e.clientY - py), -90), 90);
lon += (e.clientX - px);
while (lon < 0) lon += 360;
lon %= 360;
draw();
}
px = e.clientX;
py = e.clientY;
};
canvas.onmousewheel = function(e) {
dist = Math.max(dist - 0.1 * e.wheelDelta / 120, 0);
draw();
};
};
function draw() {
msg.innerHTML = "lat:" + lat + " lon:" + lon + " dist:" + dist.toFixed(1);
var rad = lat * Math.PI / 180;
var y = Math.sin(rad) * dist;
var r = Math.cos(rad) * dist;
var rad = lon * Math.PI / 180;
var x = Math.cos(rad) * r;
var z = Math.sin(rad) * r;
var vMatrix = m.identity(m.create());
var mvpMatrix = m.identity(m.create());
m.lookAt([x, y, z], [0, 0, 0], [0, 1, 0], vMatrix);
m.multiply(pMatrix, vMatrix, mvpMatrix);
m.multiply(mvpMatrix, mMatrix, mvpMatrix);
gl.clearColor(0x64 / 0xff, 0x95 / 0xff, 0xed / 0xff, 1);
gl.clearDepth(1);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.uniformMatrix4fv(uniLocation[0], false, mvpMatrix);
gl.drawElements(gl.TRIANGLES, indices.length, gl.UNSIGNED_SHORT, 0);
gl.flush();
}
function createShader(id) {
var element = document.getElementById(id);
if (! element) return;
const types = {
"text/x-vertex": gl.VERTEX_SHADER,
"text/x-fragment": gl.FRAGMENT_SHADER,
};
var shader = gl.createShader(types[element.type]);
gl.shaderSource(shader, element.text);
gl.compileShader(shader);
if (! gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return;
}
return shader;
}
function createProgram(vs, fs) {
var program = gl.createProgram();
gl.attachShader(program, vs);
gl.attachShader(program, fs);
gl.linkProgram(program);
if (! gl.getProgramParameter(program, gl.LINK_STATUS)) {
alert(gl.getProgramInfoLog(program));
return;
}
gl.useProgram(program);
return program;
}
function setAttribute(program, name, data, stride) {
var vbo = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vbo);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(data), gl.STATIC_DRAW);
var location = gl.getAttribLocation(program, name);
gl.enableVertexAttribArray(location);
gl.vertexAttribPointer(location, stride, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
}
function sphere(radius, stacks) {
// 頂点
positions = [];
colors = [];
positions.push(0, 1, 0); // x, y, z
colors.push(0.5, 0);
for (var stack = 1; stack < stacks; stack++) {
var v = stack / stacks;
var lat = Math.PI * v;
var r = Math.sin(lat);
var y = Math.cos(lat);
var slices = 4 * Math.min(stack, stacks - stack); // 放射頂点の数
for (var slice = 0; slice <= slices; slice++) {
var u = slice / slices;
var lon = 2 * Math.PI * u;
var z = Math.sin(lon) * r;
var x = Math.cos(lon) * r;
positions.push(x, y, z);
colors.push(u, v);
}
}
positions.push(0, -1, 0);
colors.push(0.5, 1);
// 索引
indices = [];
var prevHead = 0; // 前の先頭頂点番号
var prevVert = 1; // 前の頂点数
for (var stack = 0; stack < stacks / 2; stack++) {
var currHead = prevHead + prevVert; // 現在の先頭頂点番号
var currVert = 4 * (stack + 1) + 1; // 現在の頂点数
for (var quad = 0; quad < 4; quad++) { // 4象限
var prevQuad = quad * stack; // 前の象限オフセット
var currQuad = quad * (stack + 1); // 現在の象限オフセット
for (var i = 0; ; i++) {
var prev = prevHead + prevQuad + i;
var curr = currHead + currQuad + i;
indices.push(prev);
indices.push(curr);
indices.push(curr + 1);
if (stack <= i) break;
indices.push(prev);
indices.push(curr + 1);
indices.push(prev + 1);
}
}
prevHead = currHead;
prevVert = currVert;
}
for (var stack = stacks / 2 - 1; 0 <= stack; stack--) {
var currHead = prevHead + prevVert;
var currVert = 4 * stack + 1;
for (var quad = 0; quad < 4; quad++) {
var prevQuad = quad * (stack + 1);
var currQuad = quad * stack;
for (var i = 0; ; i++) {
var prev = prevHead + prevQuad + i;
var curr = currHead + currQuad + i;
indices.push(curr);
indices.push(prev + 1);
indices.push(prev);
if (stack <= i) break;
indices.push(curr);
indices.push(curr + 1);
indices.push(prev + 1);
}
}
prevHead = currHead;
prevVert = currVert;
}
}
</script>
</body>
