问题描述
我正在尝试将我的程序从 GLfloat 转换为 GLshort 以获得顶点位置，但我不确定如何在着色器中表示它.我在着色器中使用了 vec3 数据类型，但 vec3 代表 3 个浮点数.现在我需要代表 3 条短裤.据我所知，OpenGL 没有用于短裤的向量，那么在这种情况下我应该怎么做?
I'm attempting to convert my program from GLfloat to GLshort for vertex positions and I'm not sure how to represent this in the shader. I was using a vec3 datatype in the shader but vec3 represents 3 floats. Now I need to represent 3 shorts. As far as I can tell OpenGL doesn't have a vector for shorts so what am I supposed to do in this case?
推荐答案
这是因为这些信息并不存在于着色器中.
That's because this information doesn't live in the shader.
glVertexAttribPointer 提供的所有值都将转换为浮点 GLSL 值(如果它们还不是浮点数).这种转换基本上是免费的.因此，您可以将这些 glVertexAttribPointer 定义中的任何一个与 vec4 属性类型一起使用:
All values provided by glVertexAttribPointer will be converted to floating-point GLSL values (if they're not floats already). This conversion is essentially free. So you can use any of these glVertexAttribPointer definitions with a vec4 attribute type:
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, ...);
glVertexAttribPointer(0, 4, GL_UNSIGNED_SHORT, GL_TRUE, ...);
glVertexAttribPointer(0, 4, GL_SHORT, GL_TRUE, ...);
glVertexAttribPointer(0, 4, GL_SHORT, GL_FALSE, ...);
所有这些都会自动转换成vec4 .您的着色器不必知道或关心它正在被输入short、字节、整数、浮点数等.
All of these will be converted into a vec4 automatically. Your shader doesn't have to know or care that it's being fed shorts, bytes, integers, floats, etc.
第一个将按原样使用.第二个将无符号短范围 [0, 65535] 转换为 [0.0, 1.0] 浮点范围.第三个将签名的短范围 [-32768, 32767] 转换为 [-1.0, 1.0] 范围(虽然转换有点奇怪，并且对于某些 OpenGL 版本有所不同，以便允许整数 0 映射到浮点 0.0).第四个将 [-32768, 32767] 转换为 [-32768.0, 32767.0]，作为浮点范围.
The first one will be used as is. The second one will convert the unsigned short range [0, 65535] to the [0.0, 1.0] floating-point range. The third will convert the signed short range [-32768, 32767] to the [-1.0, 1.0] range (though the conversion is a bit odd and differs for certain OpenGL versions, so as to allow the integer 0 to map to the floating point 0.0). The fourth will convert [-32768, 32767] to [-32768.0, 32767.0], as a floating-point range.
仅当您使用 glVertexAttribIPointer 或 glVertexAttribLPointer 时，您用于属性的 GLSL 类型才会发生变化，这两种方法在 OpenGL ES 2.0 中均不可用.
The GLSL type you use for attributes only changes if you use glVertexAttribIPointer or glVertexAttribLPointer, neither of which is available in OpenGL ES 2.0.
简而言之:您应该始终对属性使用浮点 GLSL 类型.OpenGL 将为您完成转换.
In short: you should always use float GLSL types for attributes. OpenGL will do the conversion for you.
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