//    wearechat - generic multiplayer game with voip
//    Copyright (C) 2025 metamuffin
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License as published by
//    the Free Software Foundation, version 3 of the License only.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program.  If not, see <https://www.gnu.org/licenses/>.

struct VertexIn {
    @location(0) position: vec3<f32>,
    @location(1) normal: vec3<f32>,
    @location(2) tangent: vec4<f32>, // TODO maybe compress this
    @location(3) texcoord: vec2<f32>,
    @location(4) joint_index: vec4<u32>,
    @location(5) joint_weight: vec4<f32>,
}
struct VertexOut {
    @builtin(position) clip: vec4<f32>,
    @location(0) normal: vec3<f32>,
    @location(1) tangent: vec3<f32>,
    @location(2) tangent_binormal_sign: f32,
    @location(3) texcoord: vec2<f32>,
    @location(4) position: vec3<f32>,
}

struct PushConst {
    modelviewproject: mat4x4<f32>,
    model: mat4x4<f32>,
}

@group(3) @binding(0) var<uniform> joints: array<mat4x4<f32>, 128>;
var<push_constant>                 pc: PushConst;

@vertex
fn main(vi: VertexIn) -> VertexOut {
    let pos_in = vec4(vi.position, 1.);
    let j0 = vi.joint_weight.x * (joints[vi.joint_index.x] * pos_in);
    let j1 = vi.joint_weight.y * (joints[vi.joint_index.y] * pos_in);
    let j2 = vi.joint_weight.z * (joints[vi.joint_index.z] * pos_in);
    let j3 = vi.joint_weight.w * (joints[vi.joint_index.w] * pos_in);
    let position = j0 + j1 + j2 + j3;

    let clip = pc.modelviewproject * position;
    let vo = VertexOut(
        clip,
        normalize((pc.model * vec4(vi.normal, 0.)).xyz),
        normalize((pc.model * vec4(vi.tangent.xyz, 0.)).xyz),
        vi.tangent.w,
        vi.texcoord,
        (pc.model * vec4(vi.position, 1.)).xyz,
    );
    return vo;
}