为什么着色器会使用属性int编译错误（Android opengl es2）

Question

why shader compile error with attribute int? (Android opengl es2)

attribute vec4 a_Position;
attribute vec2 a_TexCoord;
attribute int a_fckLen; ///--error compile 
attribute float a_fckLen; //--compile ok

void main()
{

        gl_Position = u_Matrix * a_Position;
}

but float compile OK

Answer 1

From GLSL ES 1.00 (the one GL ES 2 uses) specification:

4.3.3 Attribute

...

The attribute qualifier can be used only with the data types float , vec2 , vec3 , vec4 , mat2 , mat3 , and mat4 . Attribute variables cannot be declared as arrays or structures.