From 1c727e4b8aa6092891648aa09f1a712ec2447a61 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sat, 21 Dec 2024 15:12:13 +0900
Subject: [PATCH 1/9] Make SDL2 and PNG optional, fix building on macOS

---
 CMakeLists.txt   | 54 +++++++++++++++++++++++++++++++++---------------
 src/LoadBitmap.c | 37 ++++++++++++++++++++++++++++++++-
 src/crt.c        | 15 +++++++++++++-
 src/crt.h        | 10 +++++++--
 4 files changed, 95 insertions(+), 21 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b9294e2..31658df 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,28 +2,41 @@ cmake_minimum_required(VERSION 3.6)
 
 project(Tilengine)
 
+# set an option to use libpng from the system, otherwise use bundled stb_image
+option(TILENEGINE_LIBPNG "Use the system libpng" OFF)
+
+# set an option to make the examples
+option(TILENEGINE_SAMPLES "Build the examples" OFF)
 
 file(GLOB SOURCES
      "src/*.c"
 )
 
-
 # main library
 list(REMOVE_ITEM SOURCES "src/Test.c")
 add_library(${PROJECT_NAME} ${SOURCES})
 
 if (UNIX AND NOT APPLE)
 	set(CMAKE_C_FLAGS "-m64 -msse2")
-elseif (UNIX AND APPLE)
-    target_link_libraries(${PROJECT_NAME} PRIVATE "framework")
+endif()
+
+if (TILENEGINE_LIBPNG)
+    add_definitions(-DTLN_HAVE_PNG)
+    find_package(PNG REQUIRED)
+    target_include_directories(${PROJECT_NAME} PRIVATE ${PNG_INCLUDE_DIRS})
+    target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
 endif()
 
 target_link_libraries(${PROJECT_NAME} PRIVATE "c")
 target_link_libraries(${PROJECT_NAME} PRIVATE "z")
-target_link_libraries(${PROJECT_NAME} PRIVATE "png")
 
-find_package(SDL2 REQUIRED)
-target_link_libraries(${PROJECT_NAME} PRIVATE ${SDL2_LIBRARIES})
+if (TILENGINE_SAMPLES)
+    find_package(SDL2 REQUIRED)
+    target_link_libraries(${PROJECT_NAME} PRIVATE ${SDL2_LIBRARIES})
+    add_definitions(-DTLN_HAVE_SDL2)
+else()
+    add_definitions(-DTLN_EXCLUDE_WINDOW)
+endif()
 
 target_include_directories(${PROJECT_NAME} PRIVATE include)
 
@@ -33,14 +46,21 @@ set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-result -Wno-format-truncation")
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/include/Tilengine.h
      DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 
-# test executable
-add_executable(Test src/Test.c)
-target_include_directories(Test PRIVATE include)
-target_link_libraries(Test PRIVATE "Tilengine")
-target_link_libraries(Test PRIVATE "c")
-target_link_libraries(Test PRIVATE "z")
-target_link_libraries(Test PRIVATE "png")
-target_link_libraries(Test PRIVATE "m")
-
-# samples
-add_subdirectory(samples)
\ No newline at end of file
+if (TILENGINE_SAMPLES)
+    # test executable
+    add_executable(Test src/Test.c)
+    target_include_directories(Test PRIVATE include)
+    target_link_libraries(Test PRIVATE "Tilengine")
+    target_link_libraries(Test PRIVATE "c")
+    target_link_libraries(Test PRIVATE "z")
+endif()
+
+if (TILENEGINE_LIBPNG)
+    target_link_libraries(Test PRIVATE ${PNG_LIBRARIES})
+    target_link_libraries(Test PRIVATE "m")
+endif()
+
+if (TILENEGINE_SAMPLES)
+    # samples
+    add_subdirectory(samples)
+endif()
diff --git a/src/LoadBitmap.c b/src/LoadBitmap.c
index 0060258..3110d0b 100644
--- a/src/LoadBitmap.c
+++ b/src/LoadBitmap.c
@@ -12,11 +12,16 @@
 #include <string.h>
 #include "Tilengine.h"
 #include "LoadFile.h"
-#include "png.h"
 #include "DIB.h"
 #include "Bitmap.h"
 #include "Palette.h"
 
+#if TLN_HAVE_PNG
+#include "png.h"
+#else
+#include "../../../src/Providers/Texture/stb_image.h"
+#endif
+
 static TLN_Bitmap LoadPNG (const char* filename);
 static TLN_Bitmap LoadBMP (const char* filename);
 
@@ -257,6 +262,34 @@ TLN_Bitmap TLN_LoadBitmap (const char* filename)
 	return bitmap;
 }
 
+#if !TLN_HAVE_PNG
+
+static TLN_Bitmap LoadPNG (const char* filename)
+{
+    TLN_Bitmap bitmap = NULL;
+    int width, height, bpp;
+    uint8_t* data = stbi_load (filename, &width, &height, &bpp, 0);
+    if (data)
+    {
+        bitmap = TLN_CreateBitmap (width, height, bpp * 8);
+        if (bitmap)
+        {
+            int pitch = TLN_GetBitmapPitch (bitmap);
+            uint8_t* dst = TLN_GetBitmapPtr (bitmap, 0, 0);
+            int y;
+            for (y=0; y<height; y++)
+            {
+                memcpy (dst, data + y * width * bpp, width * bpp);
+                dst += pitch;
+            }
+        }
+        stbi_image_free (data);
+    }
+    return bitmap;
+}
+
+#else
+
 /* Loads PNG using libpng 1.2 */
 static TLN_Bitmap LoadPNG (const char* filename)
 {
@@ -334,6 +367,8 @@ static TLN_Bitmap LoadPNG (const char* filename)
 	return bitmap;
 }
 
+#endif
+
 /* loads BMP */
 static TLN_Bitmap LoadBMP (const char* filename)
 {
diff --git a/src/crt.c b/src/crt.c
index 9f4728e..c2d1b9d 100644
--- a/src/crt.c
+++ b/src/crt.c
@@ -62,9 +62,11 @@ Size2D;
 
 struct _CRTHandler
 {
+#if TLN_HAVE_SDL2
 	SDL_Renderer* renderer;
 	SDL_Texture* framebuffer;
 	SDL_Texture* overlay;
+#endif
 	Size2D size_fb;
 	uint8_t glow;
 	bool blur;
@@ -72,6 +74,9 @@ struct _CRTHandler
 
 /* private prototypes */
 static void hblur(uint8_t* scan, int width, int height, int pitch);
+
+#if TLN_HAVE_SDL2
+
 static SDL_Texture* create_tiled_texture(SDL_Renderer* renderer, int width, int height, int tile_width, int tile_height, const uint8_t* tile_data);
 
 /* create CRT effect */
@@ -142,6 +147,8 @@ void CRTSetRenderTarget(CRTHandler crt, SDL_Texture* framebuffer)
 		crt->framebuffer = framebuffer;
 }
 
+#endif
+
 void CRTIncreaseGlow(CRTHandler crt)
 {
 	if (crt != NULL && crt->glow < 255)
@@ -162,9 +169,10 @@ void CRTSetBlur(CRTHandler crt, bool blur)
 
 void CRTDelete(CRTHandler crt)
 {
+#if TLN_HAVE_SDL2
 	if (crt != NULL)
 		SDL_DestroyTexture(crt->overlay);
-
+#endif
 	free(crt);
 }
 
@@ -200,6 +208,8 @@ static void blit(const uint8_t* srcptr, uint8_t* dstptr, int srcpitch, int lines
 	}
 }
 
+#if TLN_HAVE_SDL2
+
 static SDL_Texture* create_tiled_texture(SDL_Renderer* renderer, int width, int height, int tile_width, int tile_height, const uint8_t* tile_data)
 {
 	SDL_Surface* surface = SDL_CreateRGBSurface(0, width, height, 32, 0, 0, 0, 0);
@@ -222,3 +232,6 @@ static SDL_Texture* create_tiled_texture(SDL_Renderer* renderer, int width, int
 	SDL_FreeSurface(surface);
 	return texture;
 }
+
+#endif
+
diff --git a/src/crt.h b/src/crt.h
index 085bfa2..2726ed1 100644
--- a/src/crt.h
+++ b/src/crt.h
@@ -2,7 +2,10 @@
 #define _CRT_H
 
 #include <stdbool.h>
+
+#if TILEENGINE_HAVE_SDL2
 #include "SDL2/SDL.h"
+#endif
 
 typedef enum
 {
@@ -18,9 +21,12 @@ typedef struct _CRTHandler* CRTHandler;
 extern "C"{
 #endif
 
-	CRTHandler CRTCreate(SDL_Renderer* renderer, SDL_Texture* framebuffer, CRTType type, int wnd_width, int wnd_height, bool blur);
+#if TILEENGINE_HAVE_SDL2
+	CRTHandler CRTCreate(SDL_Renderer* renderer, SDL_Texture* framebuffer,
+                         CRTType type, int wnd_width, int wnd_height, bool blur);
 	void CRTDraw(CRTHandler crt, void* pixels, int pitch, SDL_Rect* dstrect);
 	void CRTSetRenderTarget(CRTHandler crt, SDL_Texture* framebuffer);
+#endif
 	void CRTIncreaseGlow(CRTHandler crt);
 	void CRTDecreaseGlow(CRTHandler crt);
 	void CRTSetBlur(CRTHandler crt, bool blur);
@@ -30,4 +36,4 @@ extern "C"{
 }
 #endif
 
-#endif
\ No newline at end of file
+#endif

From 835c5e3c0db560284e08fd1f313648e0d2634ec8 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sat, 21 Dec 2024 15:21:10 +0900
Subject: [PATCH 2/9] Update README

---
 CMakeLists.txt | 10 +++++-----
 README.md      |  7 +++++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 31658df..c414ea3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,10 +3,10 @@ cmake_minimum_required(VERSION 3.6)
 project(Tilengine)
 
 # set an option to use libpng from the system, otherwise use bundled stb_image
-option(TILENEGINE_LIBPNG "Use the system libpng" OFF)
+option(TLN_OPTION_LIBPNG "Use the system libpng" OFF)
 
 # set an option to make the examples
-option(TILENEGINE_SAMPLES "Build the examples" OFF)
+option(TLN_OPTION_SAMPLES "Build the examples" OFF)
 
 file(GLOB SOURCES
      "src/*.c"
@@ -20,7 +20,7 @@ if (UNIX AND NOT APPLE)
 	set(CMAKE_C_FLAGS "-m64 -msse2")
 endif()
 
-if (TILENEGINE_LIBPNG)
+if (TLN_OPTION_LIBPNG)
     add_definitions(-DTLN_HAVE_PNG)
     find_package(PNG REQUIRED)
     target_include_directories(${PROJECT_NAME} PRIVATE ${PNG_INCLUDE_DIRS})
@@ -55,12 +55,12 @@ if (TILENGINE_SAMPLES)
     target_link_libraries(Test PRIVATE "z")
 endif()
 
-if (TILENEGINE_LIBPNG)
+if (TLN_OPTION_LIBPNG)
     target_link_libraries(Test PRIVATE ${PNG_LIBRARIES})
     target_link_libraries(Test PRIVATE "m")
 endif()
 
-if (TILENEGINE_SAMPLES)
+if (TLN_OPTION_SAMPLES)
     # samples
     add_subdirectory(samples)
 endif()
diff --git a/README.md b/README.md
index 1d371a8..68f4f6b 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,13 @@
 
 Tilengine is an open source, cross-platform 2D graphics engine for creating classic/retro games with tile maps, sprites and palettes. Its unique scanline-based rendering algorithm makes raster effects a core feature, a technique used by many games running on real 2D graphics chips.
 
+# This fork
+
+This fork, in the macos branch, 
+- allows the use of a bundled stb_image instead of libpng via -DTLN_OPTION_LIBPNG=ON
+- only uses SDL2 if the -DTLN_OPTION_SAMPLES=ON flag is set
+- fixes macOS setting issues in the CMakeLists.txt
+
 http://www.tilengine.org
 
 # Contents

From 3239b6791146f8bd5f1d3dc207e9f170c47daed6 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sun, 22 Dec 2024 00:50:46 +0900
Subject: [PATCH 3/9] Factor to allow calling from other engines

---
 samples/Ship.c    |   4 +
 samples/Shooter.c | 194 +++++++++++++++++++++++++---------------------
 2 files changed, 109 insertions(+), 89 deletions(-)

diff --git a/samples/Ship.c b/samples/Ship.c
index 382d753..4f893e0 100644
--- a/samples/Ship.c
+++ b/samples/Ship.c
@@ -49,6 +49,10 @@ Actor* CreateShip (void)
 	return actor;
 }
 
+#if !TLN_HAVE_SDL2
+bool TLN_GetInput(TLN_Input id) { return false; }
+#endif
+
 void ShipTasks (Actor* actor)
 {
 	Ship* ship = (Ship*)actor->usrdata;
diff --git a/samples/Shooter.c b/samples/Shooter.c
index eb3bba8..cd144fc 100644
--- a/samples/Shooter.c
+++ b/samples/Shooter.c
@@ -97,48 +97,111 @@ static void FreeLayer (int index)
 	TLN_DeleteTilemap (layer->tilemap);
 }
 
+void ShooterInit(const char* resourceRoot)
+{
+    int c;
+
+    /* setup engine */
+    TLN_Init (WIDTH,HEIGHT, MAX_LAYER, MAX_ACTOR, 0);
+    TLN_SetRasterCallback (raster_callback);
+    TLN_SetBGColor (136,238,204);
+
+    /* load resources*/
+    TLN_SetLoadPath (resourceRoot);
+    spritesets[SPRITESET_MAIN] = TLN_LoadSpriteset ("FireLeo");
+    spritesets[SPRITESET_HELLARM] = TLN_LoadSpriteset ("HellArm");
+    LoadLayer (LAYER_FOREGROUND, "TF4_fg1");
+    LoadLayer (LAYER_BACKGROUND, "TF4_bg1");
+
+    /* create sequences from sprite names */
+    sequences[SEQ_CLAW  ] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "claw", 4);
+    sequences[SEQ_BLADE1] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "bladeb", 2);
+    sequences[SEQ_BLADE2] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "blades", 2);
+    sequences[SEQ_EXPLO1] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "explb", 3);
+    sequences[SEQ_EXPLO2] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "expls", 2);
+
+    /* create actors */
+    CreateActors (MAX_ACTOR);
+    CreateShip ();
+    BuildSinTable ();
+
+    /* compute increments for background scroll*/
+    inc_background[0] = float2fix(1.0f);    /* 1.0 pixels/frame */
+    inc_background[1] = float2fix(1.2f);    /* 1.2 pixels/frame*/
+    inc_background[2] = float2fix(8.0f);    /* 8.0 pixels/frame*/
+
+    /* initial colors */
+    for (c=0; c<3; c++)
+    {
+        sky_hi[c] = sky1[c];
+        sky_lo[c] = sky2[c];
+    }
+    for (c=0; c<MAX_LAYER; c++)
+        palettes[c] = TLN_ClonePalette (TLN_GetTilesetPalette (layers[c].tileset));
+}
+
+void ShooterRun() {
+    /* timekeeper */
+    int c;
+
+    time = frame;
+
+    /* bg color (sky) */
+    if (time>=PAL_T0 && time<=PAL_T1 && (time&0x07)==0)
+    {
+        /* sky color */
+        for (c=0; c<3; c++)
+        {
+            sky_hi[c] = lerp(time, PAL_T0,PAL_T1, sky1[c], sky3[c]);
+            sky_lo[c] = lerp(time, PAL_T0,PAL_T1, sky2[c], sky4[c]);
+        }
+
+        for (c=0; c<MAX_LAYER; c++)
+        {
+            if (palettes[c])
+                TLN_DeletePalette (palettes[c]);
+            palettes[c] = TLN_ClonePalette (TLN_GetTilesetPalette (layers[c].tileset));
+        }
+    }
+
+    /* scroll */
+    for (c=0; c<3; c++)
+        pos_background[c] += inc_background[c];
+
+    /* layers */
+    TLN_SetLayer (LAYER_BACKGROUND, layers[LAYER_FOREGROUND].tileset, layers[LAYER_FOREGROUND].tilemap);
+    TLN_SetLayer (LAYER_FOREGROUND, layers[LAYER_BACKGROUND].tileset, layers[LAYER_BACKGROUND].tilemap);
+    TLN_SetLayerPosition (LAYER_BACKGROUND, time/3, 160);
+    TLN_SetLayerPosition (LAYER_FOREGROUND, fix2int (pos_background[0]), 64);
+    TLN_SetLayerPalette (LAYER_FOREGROUND, palettes[LAYER_BACKGROUND]);
+    TLN_SetLayerPalette (LAYER_BACKGROUND, palettes[LAYER_FOREGROUND]);
+
+    if (time < 500)
+    {
+        if (rand()%30 == 1)
+            CreateEnemy ();
+    }
+    else if (time==600)
+        CreateBoss ();
+
+    /* actors */
+    TasksActors (time);
+
+    frame++;
+}
+
+void ShooterRelease() {
+    /* deinit */
+    FreeLayer (LAYER_FOREGROUND);
+    FreeLayer (LAYER_BACKGROUND);
+    TLN_Deinit ();
+}
+
+#if TLN_HAVE_SDL2
 /* entry point */
 int main (int argc, char *argv[])
 {
-	int c;
-
-	/* setup engine */
-	TLN_Init (WIDTH,HEIGHT, MAX_LAYER, MAX_ACTOR, 0);
-	TLN_SetRasterCallback (raster_callback);
-	TLN_SetBGColor (136,238,204);
-
-	/* load resources*/
-	TLN_SetLoadPath ("assets/tf4");
-	spritesets[SPRITESET_MAIN] = TLN_LoadSpriteset ("FireLeo");
-	spritesets[SPRITESET_HELLARM] = TLN_LoadSpriteset ("HellArm");
-	LoadLayer (LAYER_FOREGROUND, "TF4_fg1");
-	LoadLayer (LAYER_BACKGROUND, "TF4_bg1");
-
-	/* create sequences from sprite names */
-	sequences[SEQ_CLAW  ] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "claw", 4);
-	sequences[SEQ_BLADE1] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "bladeb", 2);
-	sequences[SEQ_BLADE2] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "blades", 2);
-	sequences[SEQ_EXPLO1] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "explb", 3);
-	sequences[SEQ_EXPLO2] = TLN_CreateSpriteSequence (NULL, spritesets[SPRITESET_MAIN], "expls", 2);
-
-	/* create actors */
-	CreateActors (MAX_ACTOR);
-	CreateShip ();
-	BuildSinTable ();
-
-	/* compute increments for background scroll*/
-	inc_background[0] = float2fix(1.0f);	/* 1.0 pixels/frame */
-	inc_background[1] = float2fix(1.2f);	/* 1.2 pixels/frame*/
-	inc_background[2] = float2fix(8.0f);	/* 8.0 pixels/frame*/
-
-	/* initial colors */
-	for (c=0; c<3; c++)
-	{
-		sky_hi[c] = sky1[c];
-		sky_lo[c] = sky2[c];
-	}
-	for (c=0; c<MAX_LAYER; c++)
-		palettes[c] = TLN_ClonePalette (TLN_GetTilesetPalette (layers[c].tileset));
+    ShooterInit("assets/tf4");
 
 	/* startup display */
 	TLN_CreateWindow (NULL, 0);
@@ -146,63 +209,16 @@ int main (int argc, char *argv[])
 	/* main loop */
 	while (TLN_ProcessWindow ())
 	{
-		/* timekeeper */
-		time = frame;
-
-		/* bg color (sky) */
-		if (time>=PAL_T0 && time<=PAL_T1 && (time&0x07)==0)
-		{
-			/* sky color */
-			for (c=0; c<3; c++)
-			{
-				sky_hi[c] = lerp(time, PAL_T0,PAL_T1, sky1[c], sky3[c]);
-				sky_lo[c] = lerp(time, PAL_T0,PAL_T1, sky2[c], sky4[c]);
-			}
-
-			for (c=0; c<MAX_LAYER; c++)
-			{
-				if (palettes[c])
-					TLN_DeletePalette (palettes[c]);
-				palettes[c] = TLN_ClonePalette (TLN_GetTilesetPalette (layers[c].tileset));
-			}
-		}
-
-		/* scroll */
-		for (c=0; c<3; c++)
-			pos_background[c] += inc_background[c];
-
-		/* layers */
-		TLN_SetLayer (LAYER_BACKGROUND, layers[LAYER_FOREGROUND].tileset, layers[LAYER_FOREGROUND].tilemap);
-		TLN_SetLayer (LAYER_FOREGROUND, layers[LAYER_BACKGROUND].tileset, layers[LAYER_BACKGROUND].tilemap);
-		TLN_SetLayerPosition (LAYER_BACKGROUND, time/3, 160);
-		TLN_SetLayerPosition (LAYER_FOREGROUND, fix2int (pos_background[0]), 64);
-		TLN_SetLayerPalette (LAYER_FOREGROUND, palettes[LAYER_BACKGROUND]);
-		TLN_SetLayerPalette (LAYER_BACKGROUND, palettes[LAYER_FOREGROUND]);
-		
-		if (time < 500)
-		{
-			if (rand()%30 == 1)
-				CreateEnemy ();
-		}
-		else if (time==600)
-			CreateBoss ();
-
-		/* actors */
-		TasksActors (time);
+        ShooterRun();
 
 		/* render to window */
 		TLN_DrawFrame (time);
-
-		frame++;
 	}
 
-	/* deinit */
-	FreeLayer (LAYER_FOREGROUND);
-	FreeLayer (LAYER_BACKGROUND);
-	TLN_Deinit ();
-
+    ShooterRelease();
 	return 0;
 }
+#endif
 
 /* raster callback (virtual HBLANK) */
 static void raster_callback (int line)

From 136dc37a635da4ddcdaff4cb3815a9e99f698da0 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sun, 22 Dec 2024 13:29:18 +0900
Subject: [PATCH 4/9] Better handling of libpng

---
 CMakeLists.txt   | 22 ++++++++++++++++------
 samples/Ship.c   |  4 ----
 src/LoadBitmap.c |  3 ++-
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c414ea3..ebf2fbf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.6)
 project(Tilengine)
 
 # set an option to use libpng from the system, otherwise use bundled stb_image
-option(TLN_OPTION_LIBPNG "Use the system libpng" OFF)
+option(TLN_OPTION_LIBPNG "Use the system libpng" ON)
 
 # set an option to make the examples
 option(TLN_OPTION_SAMPLES "Build the examples" OFF)
@@ -22,8 +22,21 @@ endif()
 
 if (TLN_OPTION_LIBPNG)
     add_definitions(-DTLN_HAVE_PNG)
-    find_package(PNG REQUIRED)
-    target_include_directories(${PROJECT_NAME} PRIVATE ${PNG_INCLUDE_DIRS})
+
+    # this project needs png, if png is not found, let's use fetch content
+    find_package(PNG QUIET)
+    if (NOT PNG_FOUND)
+        include(FetchContent)
+        FetchContent_Declare(
+            libpng
+            GIT_REPOSITORY https://github.com/pnggroup/libpng.git
+            GIT_TAG v1.6.44
+        )
+        FetchContent_MakeAvailable(libpng)
+        set(PNG_LIBRARIES png_static)
+    else()
+        target_include_directories(${PROJECT_NAME} PRIVATE ${PNG_INCLUDE_DIRS})
+    endif()
     target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
 endif()
 
@@ -53,9 +66,6 @@ if (TILENGINE_SAMPLES)
     target_link_libraries(Test PRIVATE "Tilengine")
     target_link_libraries(Test PRIVATE "c")
     target_link_libraries(Test PRIVATE "z")
-endif()
-
-if (TLN_OPTION_LIBPNG)
     target_link_libraries(Test PRIVATE ${PNG_LIBRARIES})
     target_link_libraries(Test PRIVATE "m")
 endif()
diff --git a/samples/Ship.c b/samples/Ship.c
index 4f893e0..382d753 100644
--- a/samples/Ship.c
+++ b/samples/Ship.c
@@ -49,10 +49,6 @@ Actor* CreateShip (void)
 	return actor;
 }
 
-#if !TLN_HAVE_SDL2
-bool TLN_GetInput(TLN_Input id) { return false; }
-#endif
-
 void ShipTasks (Actor* actor)
 {
 	Ship* ship = (Ship*)actor->usrdata;
diff --git a/src/LoadBitmap.c b/src/LoadBitmap.c
index 3110d0b..9387d32 100644
--- a/src/LoadBitmap.c
+++ b/src/LoadBitmap.c
@@ -119,7 +119,8 @@ static TLN_Bitmap Convert24ToIndexed(TLN_Bitmap source)
 		for (x = 0; x < source->width; x += 1)
 		{
 			uint32_t value = PackRGB32(srccolor->r, srccolor->g, srccolor->b);
-			*dstcolor = set_get_index(&colors, value) + 1;
+            uint8_t idx =  set_get_index(&colors, value);
+            *dstcolor = !idx ? 0 : idx + 1;
 			srccolor += 1;
 			dstcolor += 1;
 		}

From 844aa0b03311a3a943d187714eda2313a1dc25ca Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Wed, 1 Jan 2025 21:39:05 +0900
Subject: [PATCH 5/9] Optional libpng

---
 CMakeLists.txt | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ebf2fbf..1b6c178 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,7 @@ project(Tilengine)
 
 # set an option to use libpng from the system, otherwise use bundled stb_image
 option(TLN_OPTION_LIBPNG "Use the system libpng" ON)
+option(TLN_OPTION_BUILD_LIBPNG "Build libpng from source" OFF)
 
 # set an option to make the examples
 option(TLN_OPTION_SAMPLES "Build the examples" OFF)
@@ -21,11 +22,9 @@ if (UNIX AND NOT APPLE)
 endif()
 
 if (TLN_OPTION_LIBPNG)
-    add_definitions(-DTLN_HAVE_PNG)
-
     # this project needs png, if png is not found, let's use fetch content
     find_package(PNG QUIET)
-    if (NOT PNG_FOUND)
+    if (NOT PNG_FOUND AND TLN_OPTION_BUILD_LIBPNG)
         include(FetchContent)
         FetchContent_Declare(
             libpng
@@ -34,10 +33,18 @@ if (TLN_OPTION_LIBPNG)
         )
         FetchContent_MakeAvailable(libpng)
         set(PNG_LIBRARIES png_static)
-    else()
+        add_definitions(-DTLN_HAVE_PNG)
+        target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
+    endif()
+    if (NOT PNG_FOUND AND NOT TLN_OPTION_BUILD_LIBPNG)
+        # clear the PNG_LIBRARY variable
+        unset(PNG_LIBRARY CACHE)
+    endif()
+    if (PNG_FOUND)
+        add_definitions(-DTLN_HAVE_PNG)
         target_include_directories(${PROJECT_NAME} PRIVATE ${PNG_INCLUDE_DIRS})
+        target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
     endif()
-    target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
 endif()
 
 target_link_libraries(${PROJECT_NAME} PRIVATE "c")
@@ -66,6 +73,10 @@ if (TILENGINE_SAMPLES)
     target_link_libraries(Test PRIVATE "Tilengine")
     target_link_libraries(Test PRIVATE "c")
     target_link_libraries(Test PRIVATE "z")
+    if (TLN_OPTION_LIBPNG)
+        target_include_directories(Test PRIVATE ${PNG_INCLUDE_DIRS})
+        target_link_libraries(Test PRIVATE ${PNG_LIBRARIES})
+    endif()
     target_link_libraries(Test PRIVATE ${PNG_LIBRARIES})
     target_link_libraries(Test PRIVATE "m")
 endif()

From eb27edc7887135dd6cc39275f166a38ede821913 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sun, 2 Feb 2025 13:10:03 -0800
Subject: [PATCH 6/9] Filter gcc specific warning

---
 CMakeLists.txt         | 7 ++++++-
 samples/CMakeLists.txt | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1b6c178..131e8da 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -61,7 +61,12 @@ endif()
 target_include_directories(${PROJECT_NAME} PRIVATE include)
 
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -O2 -fpic -DLIB_EXPORTS")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-result -Wno-format-truncation")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-result")
+
+# gcc specific
+if (UNIX AND NOT APPLE)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-format-truncation")
+endif()
 
 file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/include/Tilengine.h
      DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
diff --git a/samples/CMakeLists.txt b/samples/CMakeLists.txt
index 241c8e0..492d4f5 100644
--- a/samples/CMakeLists.txt
+++ b/samples/CMakeLists.txt
@@ -19,7 +19,12 @@ find_package(SDL2 REQUIRED)
 link_libraries(${SDL2_LIBRARIES})
 
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -O2 -fpic -DLIB_EXPORTS")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-result -Wno-format-truncation")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-unused-result")
+
+# gcc specific
+if (UNIX AND NOT APPLE)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-format-truncation")
+endif()
 
 file(COPY assets DESTINATION ${CMAKE_CURRENT_BINARY_DIR})
 

From accc5c871bf495d91dd16b4f2753453f14c6225c Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sun, 2 Feb 2025 13:18:28 -0800
Subject: [PATCH 7/9] silence warning about group logical ands

---
 src/Layer.c | 6 ++++--
 src/Layer.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/Layer.c b/src/Layer.c
index 98b3c3a..b1a697d 100644
--- a/src/Layer.c
+++ b/src/Layer.c
@@ -757,10 +757,12 @@ bool TLN_EnableLayer(int nlayer)
 	layer = &engine->layers[nlayer];
 
 	/* check proper config */
-	if (layer->type == LAYER_TILE && layer->tilemap != NULL || layer->type == LAYER_BITMAP && layer->bitmap != NULL || layer->type == LAYER_OBJECT && layer->objects != NULL)
+	if ((layer->type == LAYER_TILE   && layer->tilemap != NULL) ||
+        (layer->type == LAYER_BITMAP && layer->bitmap  != NULL) ||
+        (layer->type == LAYER_OBJECT && layer->objects != NULL))
 	{
 		layer->ok = true;
-		TLN_SetLastError(TLN_ERR_IDX_LAYER);
+		TLN_SetLastError(TLN_ERR_OK);
 		return true;
 	}
 
diff --git a/src/Layer.h b/src/Layer.h
index ff9a4eb..1d83553 100644
--- a/src/Layer.h
+++ b/src/Layer.h
@@ -77,4 +77,4 @@ Layer;
 
 Layer* GetLayer(int index);
 
-#endif
\ No newline at end of file
+#endif

From fe2e61e38d934fa3e699dbf92ead6bdac2a48612 Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.com>
Date: Sun, 16 Mar 2025 18:23:55 -0700
Subject: [PATCH 8/9] the time symbol conflicts with the cstdlib time function.

---
 samples/Actor.c   |  8 ++++----
 samples/Racer.c   | 10 +++++-----
 samples/Shooter.c | 22 +++++++++++-----------
 samples/Shooter.h |  1 -
 4 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/samples/Actor.c b/samples/Actor.c
index 221a8e9..5753fd1 100644
--- a/samples/Actor.c
+++ b/samples/Actor.c
@@ -6,7 +6,7 @@
 /* local variables */
 static Actor* actors;
 static int count = 0;
-static unsigned int time;
+static unsigned int actor_time;
 
 /* local prototypes */
 static void TasksActor (Actor* actor);
@@ -112,7 +112,7 @@ void TasksActors (unsigned int t)
 	if (!actors)
 		return;
 
-	time = t;
+    actor_time = t;
 
 	for (c=0; c<count; c++)
 	{
@@ -135,13 +135,13 @@ bool CheckActorCollision (Actor* actor1, Actor* actor2)
 /* sets generic timeout */
 void SetActorTimeout (Actor* actor, int timer, int timeout)
 {
-	actor->timers[timer] = time + timeout;
+	actor->timers[timer] = actor_time + timeout;
 }
 
 /* gets generic timeout ended */
 bool GetActorTimeout (Actor* actor, int timer)
 {
-	return time >= actor->timers[timer];
+	return actor_time >= actor->timers[timer];
 }
 
 /* TasksActor */
diff --git a/samples/Racer.c b/samples/Racer.c
index 8a114c2..b25c937 100644
--- a/samples/Racer.c
+++ b/samples/Racer.c
@@ -50,7 +50,7 @@ int pos;
 int speed;
 int last_tree;
 unsigned int frame;
-unsigned int time;
+unsigned int racer_time;
 int pan = 0;
 
 static void raster_callback (int line);
@@ -81,7 +81,7 @@ int main (int argc, char* argv[])
 	while (TLN_ProcessWindow ())
 	{
 		/* timekeeper */
-		time = frame;
+		racer_time = frame;
 
 		TLN_SetLayerPosition (LAYER_PLAYFIELD, 56,72);
 		if (pos - last_tree >= 100)
@@ -92,7 +92,7 @@ int main (int argc, char* argv[])
 		}
 
 		/* input */
-		if ((time & 0x07) == 0)
+		if ((racer_time & 0x07) == 0)
 		{
 			if (TLN_GetInput (INPUT_UP) && speed < MAX_SPEED)
 				speed++;
@@ -107,10 +107,10 @@ int main (int argc, char* argv[])
 		
 		/* actores */
 		pos += speed;
-		TasksActors (time);
+		TasksActors (racer_time);
 
 		/* render to window */
-		TLN_DrawFrame (time);
+		TLN_DrawFrame (racer_time);
 
 		frame++;
 	}
diff --git a/samples/Shooter.c b/samples/Shooter.c
index cd144fc..ebf4eb3 100644
--- a/samples/Shooter.c
+++ b/samples/Shooter.c
@@ -60,7 +60,7 @@ int pos_foreground[3] = {0};
 int pos_background[3] = {0};
 int inc_background[3] = {0};
 unsigned int frame;
-unsigned int time;
+unsigned int racer_time;
 
 uint8_t sky1[3] = {107,205,255};
 uint8_t sky2[3] = {255,242,167};
@@ -144,16 +144,16 @@ void ShooterRun() {
     /* timekeeper */
     int c;
 
-    time = frame;
+    racer_time = frame;
 
     /* bg color (sky) */
-    if (time>=PAL_T0 && time<=PAL_T1 && (time&0x07)==0)
+    if (racer_time>=PAL_T0 && racer_time<=PAL_T1 && (racer_time&0x07)==0)
     {
         /* sky color */
         for (c=0; c<3; c++)
         {
-            sky_hi[c] = lerp(time, PAL_T0,PAL_T1, sky1[c], sky3[c]);
-            sky_lo[c] = lerp(time, PAL_T0,PAL_T1, sky2[c], sky4[c]);
+            sky_hi[c] = lerp(racer_time, PAL_T0,PAL_T1, sky1[c], sky3[c]);
+            sky_lo[c] = lerp(racer_time, PAL_T0,PAL_T1, sky2[c], sky4[c]);
         }
 
         for (c=0; c<MAX_LAYER; c++)
@@ -171,21 +171,21 @@ void ShooterRun() {
     /* layers */
     TLN_SetLayer (LAYER_BACKGROUND, layers[LAYER_FOREGROUND].tileset, layers[LAYER_FOREGROUND].tilemap);
     TLN_SetLayer (LAYER_FOREGROUND, layers[LAYER_BACKGROUND].tileset, layers[LAYER_BACKGROUND].tilemap);
-    TLN_SetLayerPosition (LAYER_BACKGROUND, time/3, 160);
+    TLN_SetLayerPosition (LAYER_BACKGROUND, racer_time/3, 160);
     TLN_SetLayerPosition (LAYER_FOREGROUND, fix2int (pos_background[0]), 64);
     TLN_SetLayerPalette (LAYER_FOREGROUND, palettes[LAYER_BACKGROUND]);
     TLN_SetLayerPalette (LAYER_BACKGROUND, palettes[LAYER_FOREGROUND]);
 
-    if (time < 500)
+    if (racer_time < 500)
     {
         if (rand()%30 == 1)
             CreateEnemy ();
     }
-    else if (time==600)
+    else if (racer_time==600)
         CreateBoss ();
 
     /* actors */
-    TasksActors (time);
+    TasksActors (racer_time);
 
     frame++;
 }
@@ -212,7 +212,7 @@ int main (int argc, char *argv[])
         ShooterRun();
 
 		/* render to window */
-		TLN_DrawFrame (time);
+		TLN_DrawFrame (racer_time);
 	}
 
     ShooterRelease();
@@ -234,7 +234,7 @@ static void raster_callback (int line)
 
 	/* foreground */
 	if (line==32)
-		TLN_SetLayerPosition (LAYER_BACKGROUND, time/4, 160);
+		TLN_SetLayerPosition (LAYER_BACKGROUND, racer_time/4, 160);
 
 	if (line==64)
 	{
diff --git a/samples/Shooter.h b/samples/Shooter.h
index a040a4d..77ce031 100644
--- a/samples/Shooter.h
+++ b/samples/Shooter.h
@@ -55,6 +55,5 @@ enum
 
 extern TLN_Sequence sequences[MAX_SEQ];
 extern TLN_Spriteset spritesets[MAX_SPRITESET];
-extern unsigned int time;
 
 #endif
\ No newline at end of file

From 68fafabdf70add71b2260b5bb1cd8126d31d8c6c Mon Sep 17 00:00:00 2001
From: Nick Porcino <meshula@hotmail.co>
Date: Sat, 12 Apr 2025 15:00:39 -0700
Subject: [PATCH 9/9] bump cmake ver

---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 131e8da..acdf7fd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.6)
+cmake_minimum_required(VERSION 3.16)
 
 project(Tilengine)