#version 450

layout(location = 0) in vec3 position;
layout(location = 1) in vec3 normal;
layout(location = 2) in uvec4 bone_indices;
layout(location = 3) in vec4 weights;

layout(location = 0) out vec3 frag_normal;

layout(binding = 0) uniform mvp_t {
	mat4 model;
	mat4 view;
	mat4 proj;
} mvp;

layout(binding = 1) uniform skeleton_t {
	mat4 matrices[32];
} bones;

void main() {
	const mat4 skinning_matrix
		= weights.x * bones.matrices[bone_indices.x]
		+ weights.y * bones.matrices[bone_indices.y]
		+ weights.z * bones.matrices[bone_indices.z]
		+ weights.w * bones.matrices[bone_indices.w];
	gl_Position = mvp.proj * mvp.view * mvp.model * skinning_matrix
		* vec4(position, 1.0);
	frag_normal
		= transpose(inverse(mat3(mvp.model * skinning_matrix))) * normal;
}