layout (location=0) in vec3 a_co;
layout (location=1) in vec3 a_norm;
layout (location=2) in vec2 a_uv;
-layout (location=3) in vec4 a_colour;
-layout (location=4) in vec4 a_weights;
-layout (location=5) in ivec4 a_groups;
uniform mat4 uPv;
uniform mat4x3 uMdl;