int gl_VertexID中导致Three.js错误 [英] in int gl_VertexID causing error with three.js

问题描述

我一直无法使用使用in传递的内置于顶点索引中的gl_VertexID来与Three.js一起使用

I've been having trouble with the gl_VertexID built in vertex index, passed using in, to work with Three.js

我不确定为什么，因为文档说它可以在所有版本的OpenGL中使用

I'm not sure why, as the documentation says it works in all versions of OpenGL

http://www.opengl.org/sdk/docs/manglsl/xhtml/gl_VertexID.xml

我正在使用此顶点着色器:

I'm using this vertex shader:

        uniform int freqData[64];
        uniform int fftSize;

        in int gl_VertexID;

        void main() {
            vec3 norm = normalize(position);

            int modFFT = mod(gl_VertexID, fftSize);

            vec3 newPosition = norm * float(freqData[modFFT]);

            gl_Position = projectionMatrix * modelViewMatrix * vec4( newPosition, 1.0 );
        }

我收到的错误是:

ERROR: 0:68: 'in' : syntax error

in声明似乎有问题，并且没有其他问题(错误控制台能够检测到多个编译错误).

It seems to have a problem with the in declaration, and it doesn't complain about anything else (the error console is able to detect multiple compilation errors).

非常感谢您的帮助，我正在使用昨天的Three.js版本.

I very much appreciate your help, I'm working with yesterday's Three.js build.

推荐答案

据我所知，在WebGL中，您无法访问内置的顶点索引.

As far as I'm aware, in WebGL you can't access built-in vertex indices.

但是，您应该能够通过提供自己的自定义属性流来模拟这一点，将其设置为与此类内置索引流等效的值.

However you should be able emulate this by providing your own custom attribute stream, set to values that would be equivalent to such built-in index stream.

在three.js中，尚未实现整数自定义属性，因此您需要使用float属性.

In three.js there are no integer custom attributes implemented yet, so you would need to use float attribute.

在此示例中检查位移"属性:

Check "displacement" attribute in this example:

http://mrdoob.github.com/three.js/examples/webgl_custom_attributes.html

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