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I'm trying to get this tutorial to work but I ran into two issues, one of which is the following.
When I run the code as is I get an error in the fragment shader saying: THREE.WebGLShader: gl.getShaderInfoLog() ERROR: 0:2: '' : No precision specified for (float). So what I did was specifying a precision for every float/vector I define like so varying highp vec3 vNormal. This eliminates the error but I don't get why? I can't find any other example where precision values are added to variable declarations. Can anybody explain why this occurs? Does it have something to do with my Browser (Chrome 38)?
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Shader precision The OpenGL ES and Vulkan graphics standards have their own definitions of data types. Variables are declared using a precision qualifier that defines the minimum precision that the implementation can use. However, an implementation can substitute a more precise variable if required.
As mentioned in how it works WebGL requires 2 shaders every time you draw something. A vertex shader and a fragment shader. Each shader is a function.
Shaders are the programs that run on GPU. Shaders are written in OpenGL ES Shader Language (known as ES SL). ES SL has variables of its own, data types, qualifiers, built-in inputs and outputs.
WebGL runs on the GPU on your computer. As such you need to provide the code that runs on that GPU. You provide that code in the form of pairs of functions. Those 2 functions are called a vertex shader and a fragment shader and they are each written in a very strictly typed C/C++ like language called GLSL.
There is no default precision in WebGL fragment shaders. (High precision is default for vertex shaders.) The easiest solution is to add
precision highp float; to all of your fragment shaders, which will eliminate the need to define the precision for all floating point vector variables, but generally,
precision mediump float; will be preferable, for performance. I do not advise lowp; the good mobile hardware of today doesn't even support it anymore, and does the equivalent of typedeffing lowp to mediump.
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