片元著色器精度聲明不可或缺

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function main(){    var canvas = document.getElementById("webgl");    var gl = getWebGLContext(canvas);    var VSHADER_SOURCE = function(){        /*         attribute vec4 a_Position;         attribute float a_PointSize;         void main(){         gl_Position = a_Position;         gl_PointSize = a_PointSize;         }         */    }.toString().match(/\/\*([^]*)\*\//)[1];    var FSHADER_SOURCE = function(){        /*      precision lowp float;         uniform vec4 u_FragColor;         void main(){         gl_FragColor = u_FragColor;         }         */    }.toString().match(/\/\*([^]*)\*\//)[1];    initShaders(gl,VSHADER_SOURCE,FSHADER_SOURCE);    var a_Position = gl.getAttribLocation(gl.program,"a_Position");    var a_PointSize = gl.getAttribLocation(gl.program,"a_PointSize");    var u_FragColor = gl.getUniformLocation(gl.program,"u_FragColor");    gl.clearColor(0.0,0.0,0.0,0.8);    gl.clear(gl.COLOR_BUFFER_BIT);    gl.uniform4f(u_FragColor, 0.1,1.0,1.0,1.0);    for (var i=0;i<10;i++){        gl.vertexAttrib3f(a_Position,(i+1)*0.1,(i+1)*0.1,0.0);        gl.vertexAttrib1f(a_PointSize, 10.0);        gl.drawArrays(gl.POINTS, 0, 1);    }}

如果：

Failed to compile shader: ERROR: 0:3: ‘‘ : No precision specified for (float) 

 

解決辦法：

在片元著色器裡面加上浮點數精度聲明（事實上，片元著色器支援所有3種精度，並不是精度不支援，只是需要聲明而已）

 

片元著色器精度聲明不可或缺