feat(renderer): 添加遮罩支持，优化绘制流程和背景渐变

src/plugins/live2d/model.rs

@@ -11,6 +11,8 @@ use std::path::Path;
 /// 一个 drawable 的渲染所需数据快照
 #[derive(Clone)]
 pub struct DrawableSnapshot {
+    /// 在 Core drawable 数组中的原始索引（用于查 mask 引用）
+    pub index: usize,
     pub texture_index: i32,
     pub draw_order: i32,
     pub render_order: i32,
@@ -23,6 +25,8 @@ pub struct DrawableSnapshot {
     pub indices: Vec<u16>,
     pub multiply_color: [f32; 4],
     pub screen_color: [f32; 4],
+    /// 本 drawable 依赖的 mask drawable 索引（空表示无遮罩）
+    pub mask_indices: Vec<i32>,
     pub mask_counts: i32,
 }
 
@@ -148,8 +152,8 @@ impl CubismModel {
         };
 
         println!(
-            "[Live2D] 模型加载成功: 参数={} drawable={} canvas={:?}x{:.0}ppu",
-            param_count, drawable_count, canvas.size, canvas.pixels_per_unit
+            "[Live2D] 模型加载成功: 参数={} drawable={} canvas={:?} origin=({:.1},{:.1})x{:.0}ppu",
+            param_count, drawable_count, canvas.size, canvas.origin[0], canvas.origin[1], canvas.pixels_per_unit
         );
 
         Ok(Self {
@@ -254,6 +258,7 @@ impl CubismModel {
             let indices = (core.csm_get_drawable_indices)(self.model);
             let multiply_colors = (core.csm_get_drawable_multiply_colors)(self.model);
             let screen_colors = (core.csm_get_drawable_screen_colors)(self.model);
+            let masks = (core.csm_get_drawable_masks)(self.model);
 
             // 先收集每个 drawable 的原始索引
             let mut items: Vec<(usize, i32)> = (0..count)
@@ -287,7 +292,18 @@ impl CubismModel {
                     let mc = *multiply_colors.add(i);
                     let sc = *screen_colors.add(i);
 
+                    // 取出本 drawable 的 mask 索引列表
+                    let mk = *mask_counts.add(i) as usize;
+                    let mut mask_indices: Vec<i32> = Vec::with_capacity(mk);
+                    if mk > 0 {
+                        let mptr = *masks.add(i);
+                        for k in 0..mk {
+                            mask_indices.push(*mptr.add(k));
+                        }
+                    }
+
                     DrawableSnapshot {
+                        index: i,
                         texture_index: *texture_indices.add(i),
                         draw_order: *draw_orders.add(i),
                         render_order: ro,
@@ -300,7 +316,8 @@ impl CubismModel {
                         indices: idx_vec,
                         multiply_color: [mc.x, mc.y, mc.z, mc.w],
                         screen_color: [sc.x, sc.y, sc.z, sc.w],
-                        mask_counts: *mask_counts.add(i),
+                        mask_indices,
+                        mask_counts: mk as i32,
                     }
                 })
                 .collect()