@vertex
fn vs_main(input: VertexInput) -> VertexOutput {
    var output: VertexOutput;

    let instance_model = mat4x4<f32>(
        input.instance_model_0,
        input.instance_model_1,
        input.instance_model_2,
        input.instance_model_3
    );

    let world_pos = instance_model * vec4<f32>(input.position, 1.0);
    output.world_position = world_pos.xyz;
    output.clip_position = uniforms.projection * uniforms.view * world_pos;

    let normal_matrix = mat3x3<f32>(
        instance_model[0].xyz,
        instance_model[1].xyz,
        instance_model[2].xyz
    );
    output.world_normal = normalize(normal_matrix * input.normal);

    output.light_space_position = uniforms.light_view_projection * world_pos;

    return output;
}

@fragment
fn fs_main(input: VertexOutput) -> @location(0) vec4<f32> {
    let shadow = sample_shadow_map(input.light_space_position);

    let tile_scale = 1.0;
    let flowmap_strokes = flowmap_path_lighting_with_shadow(input.world_position, input.world_normal, tile_scale, shadow);
    let point_strokes = point_lighting_with_shadow(input.world_position, input.world_normal, vec3<f32>(0.0, 100.0, 0.0), tile_scale, shadow);
    let brightness = max(flowmap_strokes, point_strokes);

    return vec4<f32>(brightness, brightness, brightness, 1.0);
}