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click_point.html
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79 lines (70 loc) · 2.4 KB
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Canvas</title>
<style>
#box {
background-color: pink;
}
#pic {
display: block;
margin: 0 auto;
}
</style>
</head>
<body>
<div id="box">
<canvas id="pic" width="500px" height="500px">
</div>
</body>
<script src="lib/cuon-matrix.js"></script>
<script src="lib/webgl-utils.js"></script>
<script src="lib/webgl-debug.js"></script>
<script src="lib/cuon-utils.js"></script>
<script>
window.onload = (function() {
/* var VSHADER_SOURCE ='void main(){gl_Position = vec4(0.0,0.0,0.0,1.0);gl_PointSize = 23.0;}';
var FSHADER_SOURCE ='void main(){gl_FragColor = vec4(1.0,0.0,0.0,1.0);}';*/
var VSHADER_SOURCE = 'attribute vec4 a_Position;attribute float a_PointSize;void main(){gl_Position = a_Position;gl_PointSize = a_PointSize;}';
var FSHADER_SOURCE = 'void main(){gl_FragColor = vec4(1.0,0.0,0.0,1.0);}';
var canvas = document.getElementById("pic");
// ======================================================================
var gl = getWebGLContext(canvas);
//初始化着色器
initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE);
var a_Position = gl.getAttribLocation(gl.program, 'a_Position');
var a_PointSize = gl.getAttribLocation(gl.program, 'a_PointSize');
console.log(gl.program)
console.log(a_Position)
if (a_Position < 0) {
console.log("获取a_Positon的存储地址失败！")
}
canvas.onmousedown = function(ev) {
click(ev, gl, canvas, a_Position);
}
var g_points = [];
function click(ev, gl, canvas, a_Position) {
var x = ev.clientX;
var y = ev.clientY;
var rect = ev.target.getBoundingClientRect();
x = ((x - rect.left) - canvas.height / 2) / (canvas.height / 2);
y = (canvas.width / 2 - (y - rect.top)) / (canvas.width / 2);
g_points.push(x);
g_points.push(y);
console.log(g_points)
//设置画布底色
gl.clearColor(0.0, 0.0, 0.0, 1.0);
//清除颜色缓冲区
gl.clear(gl.COLOR_BUFFER_BIT);
var len = g_points.length;
for (var i = 0; i < len; i += 2) {
gl.vertexAttrib3f(a_Position, g_points[i], g_points[i + 1], 0.0);
gl.vertexAttrib1f(a_PointSize, 10.0);
//绘制
gl.drawArrays(gl.POINTS, 0, 1);
}
}
});
</script>
</html>