diff --git a/CMakeLists.txt b/CMakeLists.txt
index 58d4008..5a98c58 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,6 +9,7 @@ if(NOT CMAKE_CONFIGURATION_TYPES AND NOT CMAKE_BUILD_TYPE)
 endif()
 
 option(USE_FRAMEBUFFER "Use Linux framebuffer instead of SDL2" OFF)
+option(USE_RGB565_BACKBUFFER "Use RGB565 internal backbuffer to eliminate present conversion on RGB565 fb0" OFF)
 
 set(CORE_SOURCES
     src/Core/Asset/ObjLoader.cpp
@@ -58,6 +59,13 @@ target_include_directories(imx6u_core PUBLIC ${CORE_INCLUDE_DIRS})
 
 if(USE_FRAMEBUFFER)
     target_compile_definitions(imx6u_core PUBLIC USE_FRAMEBUFFER)
+endif()
+
+if(USE_RGB565_BACKBUFFER)
+    target_compile_definitions(imx6u_core PUBLIC USE_RGB565_BACKBUFFER)
+endif()
+
+if(USE_FRAMEBUFFER)
 else()
     if(WIN32)
         if(CMAKE_SIZEOF_VOID_P EQUAL 8)
@@ -106,6 +114,15 @@ function(imx6u_configure_app_target target_name)
             "${SDL2_DLL}"
             "$<TARGET_FILE_DIR:${target_name}>"
         )
+    elseif(SDL2_image_FOUND)
+        add_executable(SpriteAssetTool ${SPRITE_ASSET_TOOL_SOURCES})
+        target_include_directories(SpriteAssetTool PRIVATE
+            src/Core/Asset
+            src/Core/RenderData
+        )
+        target_link_libraries(SpriteAssetTool PRIVATE SDL2::SDL2 SDL2_image::SDL2_image)
+    else()
+        message(STATUS "SpriteAssetTool disabled: SDL2_image was not found")
     endif()
 
     if(MSVC)
diff --git a/src/Core/Core/DepthBuffer.cpp b/src/Core/Core/DepthBuffer.cpp
index 4fea6ad..839ff28 100644
--- a/src/Core/Core/DepthBuffer.cpp
+++ b/src/Core/Core/DepthBuffer.cpp
@@ -1,34 +1,51 @@
 #include "DepthBuffer.h"
-#include <cstdint>
-#include <algorithm>
-#include <cmath>
+#include <cstring>
 
 namespace Core
 {
-	void DepthBuffer::clear(const float depth)
+	DepthBuffer::DepthBuffer(int32_t w, int32_t h)
+		: width(w), height(h), buffer(static_cast<size_t>(w) * h, 0xFFFFu)
 	{
-		std::fill(buffer.begin(), buffer.end(), depth);
 	}
 
-	float DepthBuffer::get_depth(const int32_t x, const int32_t y) const
+	void DepthBuffer::clear(uint16_t depth)
+	{
+		// 对 0x0000 或 0xFFFF 走 memset 快速路径
+		if (depth == 0xFFFFu || depth == 0x0000u)
+		{
+			std::memset(buffer.data(), depth == 0xFFFFu ? 0xFF : 0x00, buffer.size() * sizeof(uint16_t));
+		}
+		else
+		{
+			std::fill(buffer.begin(), buffer.end(), depth);
+		}
+	}
+
+	uint16_t DepthBuffer::get_depth_unsafe(int32_t x, int32_t y) const
+	{
+		return buffer[static_cast<size_t>(y) * width + x];
+	}
+
+	void DepthBuffer::set_depth_unsafe(int32_t x, int32_t y, uint16_t depth)
+	{
+		buffer[static_cast<size_t>(y) * width + x] = depth;
+	}
+
+	uint16_t DepthBuffer::get_depth(int32_t x, int32_t y) const
 	{
 		if (x < 0 || x >= width || y < 0 || y >= height)
 		{
-			return INFINITY;
+			return 0xFFFFu;
 		}
-		// Row-major layout with y = 0 on the first row, matching a top-left screen origin.
-		size_t index = static_cast<size_t>(y) * width + x;
-		return buffer.at(index);
+		return get_depth_unsafe(x, y);
 	}
 
-	void DepthBuffer::set_depth(const int32_t x, const int32_t y, const float depth)
+	void DepthBuffer::set_depth(int32_t x, int32_t y, uint16_t depth)
 	{
 		if (x < 0 || x >= width || y < 0 || y >= height)
 		{
 			return;
 		}
-		// Row-major layout with y = 0 on the first row, matching a top-left screen origin.
-		size_t index = static_cast<size_t>(y) * width + x;
-		buffer.at(index) = depth;
+		set_depth_unsafe(x, y, depth);
 	}
 }
diff --git a/src/Core/Core/DepthBuffer.h b/src/Core/Core/DepthBuffer.h
index 711553e..a9ebeff 100644
--- a/src/Core/Core/DepthBuffer.h
+++ b/src/Core/Core/DepthBuffer.h
@@ -2,7 +2,6 @@
 #include <cstdint>
 #include <vector>
 #include "Vector2.h"
-#include <cmath>
 #include <cstddef>
 
 namespace Core
@@ -12,7 +11,7 @@ namespace Core
 	private:
 		int32_t width;
 		int32_t height;
-		std::vector<float> buffer;
+		std::vector<uint16_t> buffer;
 
 	public:
 		int32_t get_width() const { return width; }
@@ -23,16 +22,20 @@ namespace Core
 
 		void* get_buffer() const { return (void*)buffer.data(); }
 
-		DepthBuffer(int32_t width, int32_t height) :width(width), height(height), buffer(std::vector<float>(width* height, INFINITY)) {}
+		DepthBuffer(int32_t width, int32_t height);
 
-		void clear(const float depth = INFINITY);
+		// 默认清为 0xFFFF（最远），语义保持"越小越近"
+		void clear(uint16_t depth = 0xFFFFu);
 
-		float get_depth(const Math::Vector2Int position) const { return get_depth(position.x, position.y); }
+		// 热路径快路径：无边界检查，调用方需确保坐标合法
+		uint16_t get_depth_unsafe(int32_t x, int32_t y) const;
+		void set_depth_unsafe(int32_t x, int32_t y, uint16_t depth);
 
-		float get_depth(const int32_t x, const int32_t y) const;
+		// 安全版本：带边界检查，越界返回最远深度
+		uint16_t get_depth(const Math::Vector2Int position) const { return get_depth(position.x, position.y); }
+		uint16_t get_depth(int32_t x, int32_t y) const;
 
-		void set_depth(const Math::Vector2Int position, const float depth) { set_depth(position.x, position.y, depth); }
-
-		void set_depth(const int32_t x, const int32_t y, const float depth);
+		void set_depth(const Math::Vector2Int position, uint16_t depth) { set_depth(position.x, position.y, depth); }
+		void set_depth(int32_t x, int32_t y, uint16_t depth);
 	};
-};
+}
diff --git a/src/Core/Core/FrameBuffer.cpp b/src/Core/Core/FrameBuffer.cpp
index 9b42cbc..48961c0 100644
--- a/src/Core/Core/FrameBuffer.cpp
+++ b/src/Core/Core/FrameBuffer.cpp
@@ -6,18 +6,16 @@ namespace Core
 {
 	void FrameBuffer::clear(const uint32_t color)
 	{
-		std::fill(buffer.begin(), buffer.end(), color);
+		std::fill(buffer.begin(), buffer.end(), rgba_to_frame_pixel(color));
 	}
 
 
-	void FrameBuffer::set_pixel(const int32_t x, const int32_t y, const uint32_t color)
-	{
-		if (x < 0 || x >= width || y < 0 || y >= height)
-		{
-			return;
-		}
-		// Row-major layout with y = 0 on the first row, matching a top-left screen origin.
-		size_t index = static_cast<size_t>(y) * width + x;
-		buffer[index] = color;
-	}
-}
+	void FrameBuffer::set_pixel(const int32_t x, const int32_t y, const uint32_t color)
+	{
+		if (x < 0 || x >= width || y < 0 || y >= height)
+		{
+			return;
+		}
+		set_pixel_unsafe(x, y, color);
+	}
+}
diff --git a/src/Core/Core/FrameBuffer.h b/src/Core/Core/FrameBuffer.h
index 58d3694..1610755 100644
--- a/src/Core/Core/FrameBuffer.h
+++ b/src/Core/Core/FrameBuffer.h
@@ -7,12 +7,26 @@
 
 namespace Core
 {
+#ifdef USE_RGB565_BACKBUFFER
+	typedef uint16_t FramePixel;
+	inline uint16_t rgba_to_frame_pixel(uint32_t rgba)
+	{
+		const uint32_t r = (rgba >> 24) & 0xFFu;
+		const uint32_t g = (rgba >> 16) & 0xFFu;
+		const uint32_t b = (rgba >> 8) & 0xFFu;
+		return static_cast<uint16_t>(((r & 0xF8u) << 8) | ((g & 0xFCu) << 3) | (b >> 3));
+	}
+#else
+	typedef uint32_t FramePixel;
+	inline uint32_t rgba_to_frame_pixel(uint32_t rgba) { return rgba; }
+#endif
+
 	class FrameBuffer
 	{
 	private:
 		int32_t width;
 		int32_t height;
-		std::vector<uint32_t> buffer;
+		std::vector<FramePixel> buffer;
 
 	public:
 		int32_t get_width() const { return width; }
@@ -23,14 +37,15 @@ namespace Core
 
 		void* get_buffer() const { return (void*)buffer.data(); }
 
-		FrameBuffer(int32_t width, int32_t height) :width(width), height(height), buffer(std::vector<uint32_t>(width * height, 0)) {}
+		FrameBuffer(int32_t width, int32_t height)
+			: width(width), height(height), buffer(static_cast<size_t>(width) * height, 0) {}
 
 		void clear(const RenderData::Color& color)
 		{
 			clear(color.to_rgba());
 		}
 
-		void clear(const uint32_t color);
+		void clear(uint32_t color);
 
 		void set_pixel(const int32_t x, const int32_t y, const RenderData::Color& color)
 		{
@@ -43,5 +58,11 @@ namespace Core
 		}
 
 		void set_pixel(const int32_t x, const int32_t y, const uint32_t color);
+
+		// 热路径快路径：无边界检查，调用方需确保坐标在 [0, width) x [0, height) 内
+		void set_pixel_unsafe(int32_t x, int32_t y, uint32_t color)
+		{
+			buffer[static_cast<size_t>(y) * width + x] = rgba_to_frame_pixel(color);
+		}
 	};
 }
diff --git a/src/Core/Draw2D/DrawContext.cpp b/src/Core/Draw2D/DrawContext.cpp
index 5511128..e8351eb 100644
--- a/src/Core/Draw2D/DrawContext.cpp
+++ b/src/Core/Draw2D/DrawContext.cpp
@@ -143,7 +143,7 @@ namespace Core
 
 					if (has_key && pixel == key) continue;
 
-					frameBuffer->set_pixel(dst_x + sx, dst_y_abs, pixel);
+					frameBuffer->set_pixel_unsafe(dst_x + sx, dst_y_abs, pixel);
 				}
 			}
 			return;
@@ -164,7 +164,7 @@ namespace Core
 
 				if (has_key && pixel == key) continue;
 
-				frameBuffer->set_pixel(dst_x + dx_abs, dst_y_abs, pixel);
+				frameBuffer->set_pixel_unsafe(dst_x + dx_abs, dst_y_abs, pixel);
 			}
 		}
 	}
@@ -263,11 +263,23 @@ namespace Core
 	void DrawContext::fill_rect(int32_t x, int32_t y, int32_t w, int32_t h, const RenderData::Color& color)
 	{
 		const uint32_t rgba = color.to_rgba();
-		for (int32_t row = y; row < y + h; ++row)
+		const int32_t fb_w = frameBuffer->get_width();
+		const int32_t fb_h = frameBuffer->get_height();
+
+		int32_t x0 = std::max(0, x);
+		int32_t y0 = std::max(0, y);
+		int32_t x1 = std::min(fb_w, x + w);
+		int32_t y1 = std::min(fb_h, y + h);
+
+		if (x0 >= x1 || y0 >= y1) return;
+
+		uint32_t* buf = static_cast<uint32_t*>(frameBuffer->get_buffer());
+		for (int32_t row = y0; row < y1; ++row)
 		{
-			for (int32_t col = x; col < x + w; ++col)
+			uint32_t* dst = buf + row * fb_w + x0;
+			for (int32_t i = 0; i < x1 - x0; ++i)
 			{
-				frameBuffer->set_pixel(col, row, rgba);
+				dst[i] = rgba;
 			}
 		}
 	}
@@ -282,6 +294,8 @@ namespace Core
 		const int32_t ch = font.char_h;
 		const int32_t atlas_w = font.atlas.width;
 		const uint32_t* src = font.atlas.pixels;
+		const int32_t screen_w = frameBuffer->get_width();
+		const int32_t screen_h = frameBuffer->get_height();
 
 		int32_t cursor_x = x;
 		for (const char* p = text; *p; ++p)
@@ -294,15 +308,29 @@ namespace Core
 			const int32_t src_x = col * cw;
 			const int32_t src_y = row * ch;
 
-			for (int32_t sy = 0; sy < ch; ++sy)
+			// 整字符在屏幕外则跳过
+			if (cursor_x + cw <= 0 || cursor_x >= screen_w || y + ch <= 0 || y >= screen_h)
+			{
+				cursor_x += cw;
+				continue;
+			}
+
+			int32_t sy_start = 0, sy_end = ch;
+			int32_t sx_start = 0, sx_end = cw;
+			if (y < 0) sy_start = -y;
+			if (y + ch > screen_h) sy_end = screen_h - y;
+			if (cursor_x < 0) sx_start = -cursor_x;
+			if (cursor_x + cw > screen_w) sx_end = screen_w - cursor_x;
+
+			for (int32_t sy = sy_start; sy < sy_end; ++sy)
 			{
 				const uint32_t* atlas_row = src + (src_y + sy) * atlas_w;
 				const int32_t dst_y_abs = y + sy;
-				for (int32_t sx = 0; sx < cw; ++sx)
+				for (int32_t sx = sx_start; sx < sx_end; ++sx)
 				{
 					const uint32_t pixel = atlas_row[src_x + sx];
 					if ((pixel & 0xFF) == 0) continue;
-					frameBuffer->set_pixel(cursor_x + sx, dst_y_abs, rgba);
+					frameBuffer->set_pixel_unsafe(cursor_x + sx, dst_y_abs, rgba);
 				}
 			}
 			cursor_x += cw;
diff --git a/src/Core/Platform/FBDisplay.cpp b/src/Core/Platform/FBDisplay.cpp
index 5c0fc33..a168cc7 100644
--- a/src/Core/Platform/FBDisplay.cpp
+++ b/src/Core/Platform/FBDisplay.cpp
@@ -119,6 +119,23 @@ namespace Platform
 
 		if (is_rgb565)
 		{
+#ifdef USE_RGB565_BACKBUFFER
+			// backbuffer 内部已是 RGB565，直接行拷贝提交
+			const uint8_t* src_bytes = static_cast<const uint8_t*>(framebuffer->get_buffer());
+			if (static_cast<int>(finfo.line_length) == dst_width * 2)
+			{
+				std::memcpy(fb_mem, src_bytes, static_cast<size_t>(dst_height) * dst_width * 2);
+			}
+			else
+			{
+				for (int y = 0; y < dst_height; ++y)
+				{
+					std::memcpy(fb_mem + y * finfo.line_length,
+					            src_bytes + y * src_width * 2,
+					            dst_width * 2);
+				}
+			}
+#else
 			for (int y = 0; y < dst_height; ++y)
 			{
 				const uint32_t* src_row = src + y * src_width;
@@ -128,6 +145,7 @@ namespace Platform
 					dst_row[x] = rgba_to_rgb565(src_row[x]);
 				}
 			}
+#endif
 			return;
 		}
 
diff --git a/src/Core/Platform/SDLDisplay.cpp b/src/Core/Platform/SDLDisplay.cpp
index a305f6b..665f371 100644
--- a/src/Core/Platform/SDLDisplay.cpp
+++ b/src/Core/Platform/SDLDisplay.cpp
@@ -42,9 +42,16 @@ namespace Platform
 			return false;
 		}
 
+#ifdef USE_RGB565_BACKBUFFER
+		const Uint32 sdl_pixel_format = SDL_PIXELFORMAT_RGB565;
+		const int pixel_bytes = 2;
+#else
+		const Uint32 sdl_pixel_format = SDL_PIXELFORMAT_RGBA8888;
+		const int pixel_bytes = 4;
+#endif
 		texture = SDL_CreateTexture(
 			renderer,
-			SDL_PIXELFORMAT_RGBA8888,
+			sdl_pixel_format,
 			SDL_TEXTUREACCESS_STREAMING,
 			width,
 			height
@@ -60,7 +67,12 @@ namespace Platform
 
 	void SDLDisplay::present(const Core::FrameBuffer* framebuffer)
 	{
-		SDL_UpdateTexture(texture, nullptr, framebuffer->get_buffer(), width * sizeof(uint32_t));
+#ifdef USE_RGB565_BACKBUFFER
+		const int pixel_bytes = 2;
+#else
+		const int pixel_bytes = 4;
+#endif
+		SDL_UpdateTexture(texture, nullptr, framebuffer->get_buffer(), width * pixel_bytes);
 		SDL_RenderClear(renderer);
 		SDL_RenderCopy(renderer, texture, nullptr, nullptr);
 		SDL_RenderPresent(renderer);
diff --git a/src/Core/Rasterizer/TriangleRasterizer.cpp b/src/Core/Rasterizer/TriangleRasterizer.cpp
index 7efc132..a478790 100644
--- a/src/Core/Rasterizer/TriangleRasterizer.cpp
+++ b/src/Core/Rasterizer/TriangleRasterizer.cpp
@@ -6,6 +6,19 @@
 #include <algorithm>
 #include <cstdint>
 
+namespace
+{
+	// 临时边界：将 float 深度映射到 uint16_t 定点深度。
+	// 约定：0.0 ~ 1.0 映射到 0 ~ 65535，越小越近。
+	// TODO: 等 TriangleRasterizer 重构为定点后删除此转换。
+	inline uint16_t temp_float_depth_to_uint16(float z)
+	{
+		if (z <= 0.0f) return 0u;
+		if (z >= 1.0f) return 0xFFFFu;
+		return static_cast<uint16_t>(z * 65535.0f + 0.5f);
+	}
+}
+
 namespace Rasterizer
 {
 	void TriangleRasterizer::DrawTriangle2D(const RenderData::Triangle& triangle, const RenderData::Color color)
@@ -42,13 +55,14 @@ namespace Rasterizer
 
 				if (depthBuffer)
 				{
+					const uint16_t depth_u16 = temp_float_depth_to_uint16(depth);
 					// 深度越小离相机越近
-					if (depthBuffer->get_depth(x, y) < depth)
+					if (depthBuffer->get_depth(x, y) < depth_u16)
 					{
 						continue;
 					}
 
-					depthBuffer->set_depth(x, y, depth);
+					depthBuffer->set_depth(x, y, depth_u16);
 					frameBuffer->set_pixel(x, y, color.to_rgba());
 				}
 				else