Оптимизация круга

src/render/cpu/ellipse.zig

@@ -52,14 +52,41 @@ pub fn draw(ctx: *DrawContext, obj: *const Object) void {
     const x1: i32 = @min(buf_w, @as(i32, @intFromFloat(std.math.ceil(max_bx))) + 1);
     const y1: i32 = @min(buf_h, @as(i32, @intFromFloat(std.math.ceil(max_by))) + 1);
 
+    // Один раз считаем аффин buffer -> local, чтобы в цикле не вызывать cos/sin и лишние функции.
+    const t = &ctx.transform;
+    const ctx_sx = if (ctx.scale_x != 0) ctx.scale_x else 1.0;
+    const ctx_sy = if (ctx.scale_y != 0) ctx.scale_y else 1.0;
+    const inv_ctx_sx = 1.0 / ctx_sx;
+    const inv_ctx_sy = 1.0 / ctx_sy;
+    const vx = @as(f32, @floatFromInt(ctx.visible_rect.x));
+    const vy = @as(f32, @floatFromInt(ctx.visible_rect.y));
+    const t_sx = if (t.scale.scale_x != 0) t.scale.scale_x else 1.0;
+    const t_sy = if (t.scale.scale_y != 0) t.scale.scale_y else 1.0;
+    const ca = std.math.cos(-t.angle);
+    const sa = std.math.sin(-t.angle);
+    const dx_off = vx * inv_ctx_sx - t.position.x;
+    const dy_off = vy * inv_ctx_sy - t.position.y;
+    const loc_x_off = (dx_off * ca - dy_off * sa) / t_sx;
+    const loc_y_off = (dx_off * sa + dy_off * ca) / t_sy;
+    const m00 = inv_ctx_sx * ca / t_sx;
+    const m01 = -inv_ctx_sy * sa / t_sx;
+    const m10 = inv_ctx_sx * sa / t_sy;
+    const m11 = inv_ctx_sy * ca / t_sy;
+    const inv_rx = 1.0 / rx;
+    const inv_ry = 1.0 / ry;
+
     var by: i32 = y0;
     while (by < y1) : (by += 1) {
+        const buf_y = @as(f32, @floatFromInt(by)) + 0.5;
+        const row_loc_x_off = buf_y * m01 + loc_x_off;
+        const row_loc_y_off = buf_y * m11 + loc_y_off;
         var bx: i32 = x0;
         while (bx < x1) : (bx += 1) {
-            const w = ctx.bufferToWorld(@as(f32, @floatFromInt(bx)) + 0.5, @as(f32, @floatFromInt(by)) + 0.5);
-            const loc = ctx.worldToLocal(w.x, w.y);
-            const nx = loc.x / rx;
-            const ny = loc.y / ry;
+            const buf_x = @as(f32, @floatFromInt(bx)) + 0.5;
+            const loc_x = buf_x * m00 + row_loc_x_off;
+            const loc_y = buf_x * m10 + row_loc_y_off;
+            const nx = loc_x * inv_rx;
+            const ny = loc_y * inv_ry;
             const d = nx * nx + ny * ny;
             if (d >= d_inner_sq and d <= d_outer_sq) {
                 ctx.blendPixelAtBuffer(@intCast(bx), @intCast(by), stroke);