From 2c104d7936193bb19eb52b3e4d47657ffb18a9d7 Mon Sep 17 00:00:00 2001
From: Tengu712 <genreihoutengu@gmail.com>
Date: Thu, 1 Oct 2026 01:53:23 +0900
Subject: render text

---
 src/graphics/command.rs | 115 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 src/graphics/command.rs

(limited to 'src/graphics/command.rs')

diff --git a/src/graphics/command.rs b/src/graphics/command.rs
new file mode 100644
index 0000000..54b6744
--- /dev/null
+++ b/src/graphics/command.rs
@@ -0,0 +1,115 @@
+use super::{
+    InstanceData,
+    font::{self, CharAtlas},
+};
+use glam::Vec2;
+use wgpu::Queue;
+
+pub enum HorizontalAlign {
+    Left,
+    Center,
+    Right,
+}
+
+pub enum VerticalAlign {
+    Top,
+    Center,
+    Bottom,
+}
+
+pub struct Text {
+    pub text: String,
+    pub origin: Vec2,
+    pub scale: u32,
+    pub h_align: HorizontalAlign,
+    pub v_align: VerticalAlign,
+}
+
+pub enum RenderCommand {
+    Text(Text),
+}
+
+impl RenderCommand {
+    /// 描画コマンドからインスタンス情報に変換するメソッド
+    ///
+    /// * screen_width - 画面幅
+    /// * screen_height - 画面高
+    /// * scale_factor - 画面拡大率
+    /// * queue - queue
+    /// * char_atlas - 文字テクスチャアトラス
+    /// * buf - インスタンスバッファ
+    pub fn build(
+        &self,
+        screen_width: f32,
+        screen_height: f32,
+        scale_factor: f32,
+        queue: &Queue,
+        char_atlas: &mut CharAtlas,
+        buf: &mut Vec<InstanceData>,
+    ) {
+        match self {
+            RenderCommand::Text(text) => build_text(
+                text,
+                screen_width,
+                screen_height,
+                scale_factor,
+                queue,
+                char_atlas,
+                buf,
+            ),
+        }
+    }
+}
+
+fn build_text(
+    text: &Text,
+    screen_width: f32,
+    screen_height: f32,
+    scale_factor: f32,
+    queue: &Queue,
+    char_atlas: &mut CharAtlas,
+    buf: &mut Vec<InstanceData>,
+) {
+    let scale = text.scale as f32;
+    let line_height = font::line_height(scale);
+    let mut baseline = text.origin.y + font::ascent(scale);
+
+    for line in text.text.split('\n') {
+        // NOTE: ピクセル境界に合わせるため、整数にする。
+        //       最終的にRust側でNDCに変換するが、fragmentation時に整数に直る。
+        let y = (baseline * scale_factor).round() / scale_factor;
+        let mut ox = text.origin.x;
+        let mut prev = None;
+
+        for c in line.chars() {
+            let ci = char_atlas.acquire(queue, c, scale);
+
+            if let Some(prev) = prev {
+                ox += font::kern(scale, prev, ci.glyph_id);
+            }
+            prev = Some(ci.glyph_id);
+
+            if ci.alloc_id.is_none() {
+                ox += font::h_advance(scale, ci.glyph_id);
+                continue;
+            }
+
+            // NOTE: ピクセル境界に合わせるため、整数にする。
+            //       最終的にRust側でNDCに変換するが、fragmentation時に整数に直る。
+            let x = (ox * scale_factor).round() / scale_factor;
+            let center_x = x + ci.x_offset + ci.width / 2.0;
+            let center_y = y + ci.y_offset + ci.height / 2.0;
+            buf.push(InstanceData {
+                position: Vec2::new(
+                    center_x / screen_width * 2.0 - 1.0,
+                    1.0 - center_y / screen_height * 2.0,
+                ),
+                scale: Vec2::new(ci.width / screen_width, ci.height / screen_height),
+                uv: ci.uv,
+            });
+            ox += font::h_advance(scale, ci.glyph_id);
+        }
+
+        baseline += line_height;
+    }
+}
-- 
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