WebGL 示例代码:缩放
WebGL 示例代码:缩放
本小节中,我们将使用代码演示使用WebGL修改三角形的尺寸.
<!doctype html> <html> <body> <canvas width = "300" height = "300" id = "my_Canvas"></canvas> <script> /*=================Creating a canvas=========================*/ var canvas = document.getElementById('my_Canvas'); gl = canvas.getContext('experimental-webgl'); /*===========Defining and storing the geometry==============*/ var vertices = [ -0.5,0.5,0.0, -0.5,-0.5,0.0, 0.5,-0.5,0.0, ]; //Create an empty buffer object and store vertex data var vertex_buffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW); gl.bindBuffer(gl.ARRAY_BUFFER, null); /*========================Shaders============================*/ //Vertex shader source code var vertCode = 'attribute vec4 coordinates;' + 'uniform mat4 u_xformMatrix;' + 'void main(void) {' + ' gl_Position = u_xformMatrix * coordinates;' + '}'; //Create a vertex shader program object and compile it var vertShader = gl.createShader(gl.VERTEX_SHADER); gl.shaderSource(vertShader, vertCode); gl.compileShader(vertShader); //fragment shader source code var fragCode = 'void main(void) {' + ' gl_FragColor = vec4(0.0, 0.0, 0.0, 0.1);' + '}'; //Create a fragment shader program object and compile it var fragShader = gl.createShader(gl.FRAGMENT_SHADER); gl.shaderSource(fragShader, fragCode); gl.compileShader(fragShader); //Create and use combiened shader program var shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertShader); gl.attachShader(shaderProgram, fragShader); gl.linkProgram(shaderProgram); gl.useProgram(shaderProgram); /*===================scaling==========================*/ var Sx = 1.0, Sy = 1.5, Sz = 1.0; var xformMatrix = new Float32Array([ Sx, 0.0, 0.0, 0.0, 0.0, Sy, 0.0, 0.0, 0.0, 0.0, Sz, 0.0, 0.0, 0.0, 0.0, 1.0 ]); var u_xformMatrix = gl.getUniformLocation(shaderProgram, 'u_xformMatrix'); gl.uniformMatrix4fv(u_xformMatrix, false, xformMatrix); /* ===========Associating shaders to buffer objects============*/ gl.bindBuffer(gl.ARRAY_BUFFER, vertex_buffer); var coordinatesVar = gl.getAttribLocation(shaderProgram, "coordinates"); gl.vertexAttribPointer(coordinatesVar, 3, gl.FLOAT, false, 0, 0); gl.enableVertexAttribArray(coordinatesVar); /*=================Drawing the Quad========================*/ gl.clearColor(0.5, 0.5, 0.5, 0.9); gl.enable(gl.DEPTH_TEST); gl.clear(gl.COLOR_BUFFER_BIT); gl.viewport(0,0,canvas.width,canvas.height); gl.drawArrays(gl.TRIANGLES, 0, 3); </script> </body> </html>