#version 450 core

// ---------- Vertex attributes (used in both modes) ----------
layout(location = 0) in vec2 v_position;
layout(location = 1) in vec2 v_uv;
layout(location = 2) in vec4 v_color;

// ---------- Outputs to fragment shader ----------
layout(location = 0) out vec4 f_color;
layout(location = 1) out vec2 f_local_or_uv;
layout(location = 2) out vec4 f_params;
layout(location = 3) out vec4 f_params2;
layout(location = 4) flat out uint f_kind_flags;
layout(location = 5) flat out float f_rotation;
layout(location = 6) flat out vec4 f_uv_rect;

// ---------- Uniforms (single block — avoids spirv-cross reordering on Metal) ----------
layout(set = 1, binding = 0) uniform Uniforms {
    mat4 projection;
    float dpi_scale;
    uint mode; // 0 = tessellated, 1 = SDF
};

// ---------- SDF primitive storage buffer ----------
struct Primitive {
    vec4 bounds; // 0-15:  min_x, min_y, max_x, max_y
    uint color; // 16-19: packed u8x4 (unpack with unpackUnorm4x8)
    uint kind_flags; // 20-23: kind | (flags << 8)
    float rotation; // 24-27: shader self-rotation in radians
    float _pad; // 28-31: alignment padding
    vec4 params; // 32-47: shape params part 1
    vec4 params2; // 48-63: shape params part 2
    vec4 uv_rect; // 64-79: u_min, v_min, u_max, v_max
};

layout(std430, set = 0, binding = 0) readonly buffer Primitives {
    Primitive primitives[];
};

// ---------- Entry point ----------
void main() {
    if (mode == 0u) {
        // ---- Mode 0: Tessellated (legacy) ----
        f_color = v_color;
        f_local_or_uv = v_uv;
        f_params = vec4(0.0);
        f_params2 = vec4(0.0);
        f_kind_flags = 0u;
        f_rotation = 0.0;
        f_uv_rect = vec4(0.0, 0.0, 1.0, 1.0);

        gl_Position = projection * vec4(v_position * dpi_scale, 0.0, 1.0);
    } else {
        // ---- Mode 1: SDF instanced quads ----
        Primitive p = primitives[gl_InstanceIndex];

        vec2 corner = v_position; // unit quad corners: (0,0)-(1,1)
        vec2 world_pos = mix(p.bounds.xy, p.bounds.zw, corner);
        vec2 center = 0.5 * (p.bounds.xy + p.bounds.zw);

        f_color = unpackUnorm4x8(p.color);
        f_local_or_uv = (world_pos - center) * dpi_scale; // shape-centered physical pixels
        f_params = p.params;
        f_params2 = p.params2;
        f_kind_flags = p.kind_flags;
        f_rotation = p.rotation;
        f_uv_rect = p.uv_rect;

        gl_Position = projection * vec4(world_pos * dpi_scale, 0.0, 1.0);
    }
}