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36_BlendCube.html
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36_BlendCube.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>36_BlendCube</title>
<link href="css/common.css" rel="stylesheet" />
<script src="js/gl-matrix.js"></script>
</head>
<body>
<canvas id="mycanvas"></canvas>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec4 aPosition;
attribute vec4 aColor;
uniform mat4 uModelMatrix;
uniform mat4 uViewMatrix;
uniform mat4 uProjMatrix;
uniform bool uClicked;
uniform float uAlpha;
varying vec4 vColor;
void main() {
gl_Position = uProjMatrix * uViewMatrix * uModelMatrix * aPosition;
if(uClicked) {
vColor = vec4(1.0, 0.0, 0.0, 1.0);
} else {
vColor = vec4(aColor.x, aColor.y, aColor.z, uAlpha);
}
}
</script>
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec4 vColor;
void main() {
gl_FragColor = vColor;
}
</script>
<script>
var canvas = document.getElementById('mycanvas');
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
var gl = canvas.getContext('webgl');
var vertexShader = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(vertexShader, document.getElementById('shader-vs').innerHTML);
gl.compileShader(vertexShader);
var fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(fragmentShader, document.getElementById('shader-fs').innerHTML);
gl.compileShader(fragmentShader);
var shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
gl.useProgram(shaderProgram);
var aPosition = gl.getAttribLocation(shaderProgram, 'aPosition');
var aColor = gl.getAttribLocation(shaderProgram, 'aColor');
var uModelMatrix = gl.getUniformLocation(shaderProgram, 'uModelMatrix');
var uViewMatrix = gl.getUniformLocation(shaderProgram, 'uViewMatrix');
var uProjMatrix = gl.getUniformLocation(shaderProgram, 'uProjMatrix');
var uClicked = gl.getUniformLocation(shaderProgram, 'uClicked');
var uAlpha = gl.getUniformLocation(shaderProgram, 'uAlpha');
// 模型矩阵
var model = mat4.create();
mat4.rotateX(model, mat4.create(), 0);
gl.uniformMatrix4fv(uModelMatrix, false, model);
// 视图矩阵
var view = mat4.create();
mat4.lookAt(view, vec3.fromValues(3, 4, 5), vec3.fromValues(0, 0, 0, 0), vec3.fromValues(1, 0, 0));
gl.uniformMatrix4fv(uViewMatrix, false, view);
// 投影矩阵
var proj = mat4.create();
mat4.perspective(proj, Math.PI * 90 / 180, canvas.width / canvas.height, 0.1, 10000);
gl.uniformMatrix4fv(uProjMatrix, false, proj);
// 顶点位置矩阵
var positionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, // v0-v1-v2-v3 front
1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, // v0-v3-v4-v5 right
1.0, 1.0, 1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, // v0-v5-v6-v1 up
-1.0, 1.0, 1.0, -1.0, 1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, // v1-v6-v7-v2 left
-1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, -1.0, 1.0, -1.0, -1.0, 1.0, // v7-v4-v3-v2 down
1.0, -1.0, -1.0, -1.0, -1.0, -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0 // v4-v7-v6-v5 back
]), gl.STATIC_DRAW);
gl.vertexAttribPointer(aPosition, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aPosition);
// 顶点颜色矩阵
var colorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, // v0-v1-v2-v3 front(blue)
0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, // v0-v3-v4-v5 right(green)
1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, 1.0, 0.4, 0.4, // v0-v5-v6-v1 up(red)
1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, // v1-v6-v7-v2 left
1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, // v7-v4-v3-v2 down
0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0, 0.4, 1.0, 1.0 // v4-v7-v6-v5 back
]), gl.STATIC_DRAW);
gl.vertexAttribPointer(aColor, 3, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(aColor);
// 索引矩阵
var indexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint8Array([
0, 1, 2, 0, 2, 3, // front
4, 5, 6, 4, 6, 7, // right
8, 9, 10, 8, 10, 11, // up
12, 13, 14, 12, 14, 15, // left
16, 17, 18, 16, 18, 19, // down
20, 21, 22, 20, 22, 23 // back
]), gl.STATIC_DRAW);
// 透明度
gl.uniform1f(uAlpha, 0.5);
// 渲染
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
gl.enable(gl.BLEND);
gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
var xAxisAngle = 0;
var yAxisAngle = 0;
var render = function () {
xAxisAngle += Math.PI / 180;
yAxisAngle += Math.PI / 180;
mat4.rotateX(model, mat4.create(), xAxisAngle);
mat4.rotateY(model, model, xAxisAngle);
gl.uniformMatrix4fv(uModelMatrix, false, model);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
gl.drawElements(gl.TRIANGLES, 36, gl.UNSIGNED_BYTE, 0);
}
var tick = function () {
requestAnimationFrame(tick);
render();
}
tick();
canvas.onclick = function (ev) {
var x = ev.clientX;
var y = ev.clientY;
var rect = ev.target.getBoundingClientRect();
if (x < rect.left || x > rect.right || y < rect.top || y > rect.bottom) {
return;
}
var canvasX = x - rect.left;
var canvasY = y - rect.top;
// 判断是否选中物体
var picked = false;
gl.uniform1i(uClicked, 1);
render();
var pixels = new Uint8Array(4);
gl.readPixels(canvasX, canvasY, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixels);
if (pixels[0] == 255) {
picked = true;
}
gl.uniform1i(uClicked, 0);
render();
if (picked) {
alert('你点击了正方体！');
}
}
</script>
</body>
</html>