Add software renderer implementation for SDL 1.2 backend

CMakeLists.txt

@@ -62,6 +62,7 @@ option(ENABLE_WAD16 "Enable support for WAD Version 15/16" ON)
 option(ENABLE_WAD17 "Enable support for WAD Version 17" ON)
 option(ENABLE_LEGACY_GL "Enable the legacy OpenGL renderer" ON)
 option(ENABLE_MODERN_GL "Enable the modern OpenGL renderer" ON)
+option(ENABLE_SW_RENDERER "Enable the software renderer" ON)
 if(NOT ENABLE_WAD14 AND NOT ENABLE_WAD16 AND NOT ENABLE_WAD17)
     message(FATAL_ERROR "You need to build Butterscotch with at least one WAD version enabled!")
 endif()
@@ -80,6 +81,9 @@ endif()
 if(ENABLE_MODERN_GL)
     add_compile_definitions(ENABLE_MODERN_GL)
 endif()
+if(ENABLE_SW_RENDERER)
+    add_compile_definitions(ENABLE_SW_RENDERER)
+endif()
 
 if(PLATFORM STREQUAL "web-meta")
     # Metadata-only build: just the data.win parser and its direct deps. No VM, no runner, no I/O subsystems.
@@ -165,20 +169,27 @@ if(PLATFORM STREQUAL "desktop")
     # Matches the GitHub Actions container flags (FORTIFY requires building with optimizations enabled!)
     target_compile_options(butterscotch PRIVATE "$<$<CONFIG:Release,RelWithDebInfo>:-U_FORTIFY_SOURCE;-D_FORTIFY_SOURCE=2>")
 
-    if(NOT ENABLE_LEGACY_GL AND NOT ENABLE_MODERN_GL)
+    if(NOT ENABLE_LEGACY_GL AND NOT ENABLE_MODERN_GL AND NOT ENABLE_SW_RENDERER)
         message(FATAL_ERROR "You must enable at least one renderer!")
     endif()
-    file(GLOB GL_SOURCES src/image/*.c src/gl_common/*.c)
+    file(GLOB GL_SOURCES src/image/*.c)
+    if(ENABLE_LEGACY_GL OR ENABLE_MODERN_GL)
+        file(GLOB GL_SOURCES ${GL_SOURCES} src/gl_common/*.c)
+        target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl)
+        target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl_common)
+    endif()
     if(ENABLE_LEGACY_GL)
         file(GLOB GL_SOURCES ${GL_SOURCES} src/gl_legacy/*.c)
         target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl_legacy)
     endif()
     if(ENABLE_MODERN_GL)
         file(GLOB GL_SOURCES ${GL_SOURCES} src/gl/*.c)
     endif()
+    if(ENABLE_SW_RENDERER)
+        file(GLOB GL_SOURCES ${GL_SOURCES} src/sw/*.c)
+        target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/sw)
+    endif()
     target_sources(butterscotch PRIVATE ${GL_SOURCES})
-    target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl)
-    target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/gl_common)
     target_include_directories(butterscotch PRIVATE ${CMAKE_SOURCE_DIR}/src/image)
 
     # Butterscotch VM/interpreter profiler
@@ -212,19 +223,25 @@ if(PLATFORM STREQUAL "desktop")
     endif()
 
     # GLAD
-    if(ENABLE_GLES)
-        add_compile_definitions(ENABLE_GLES)
-        add_library(glad STATIC vendor/glad-gles/src/glad.c)
-        target_include_directories(glad PUBLIC vendor/glad-gles/include)
-    else()
-        add_library(glad STATIC vendor/glad/src/glad.c)
-        target_include_directories(glad PUBLIC vendor/glad/include)
+    if(ENABLE_LEGACY_GL OR ENABLE_MODERN_GL OR DESKTOP_BACKEND STREQUAL "glfw3" OR DESKTOP_BACKEND STREQUAL "glfw2")
+        if(ENABLE_GLES)
+            add_compile_definitions(ENABLE_GLES)
+            add_library(glad STATIC vendor/glad-gles/src/glad.c)
+            target_include_directories(glad PUBLIC vendor/glad-gles/include)
+        else()
+            add_library(glad STATIC vendor/glad/src/glad.c)
+            target_include_directories(glad PUBLIC vendor/glad/include)
+        endif()
+        set(PLATFORM_LIBRARIES glad)
     endif()
 
     # stb_image
     target_include_directories(butterscotch PUBLIC vendor/stb/image)
 
-    set(PLATFORM_LIBRARIES glad m bzip2 stb_ds sha1 stb_vorbis)
+    # stb_vorbis
+    target_include_directories(butterscotch PUBLIC vendor/stb/vorbis)
+
+    set(PLATFORM_LIBRARIES ${PLATFORM_LIBRARIES} m bzip2 stb_ds sha1 stb_vorbis)
     if(MINGW)
         set(PLATFORM_LIBRARIES ${PLATFORM_LIBRARIES} opengl32 gdi32 winmm)
     elseif(NOT CMAKE_SYSTEM_NAME STREQUAL "Haiku")

Makefile

@@ -60,12 +60,18 @@ GLFW3_LIBS += $(shell pkg-config $(PKG_CONFIG_FLAGS) --libs glfw3)
 LIBS += $(GLFW3_LIBS)
 DEFINES += -DUSE_GLFW3
 ENABLE_GLAD := 1
+ifdef ENABLE_GLES
+DISABLE_SW_RENDERER := 1
+endif
 endif
 ifeq ($(DESKTOP_BACKEND),glfw2)
 GLFW2_LIBS += $(shell pkg-config $(PKG_CONFIG_FLAGS) --libs libglfw)
 LIBS += $(GLFW2_LIBS)
 DEFINES += -DUSE_GLFW2
 ENABLE_GLAD := 1
+ifdef ENABLE_GLES
+DISABLE_SW_RENDERER := 1
+endif
 endif
 ifeq ($(DESKTOP_BACKEND),sdl1)
 SDL1_LIBS += $(shell pkg-config $(PKG_CONFIG_FLAGS) --libs sdl)
@@ -114,6 +120,13 @@ SRCS += $(wildcard src/gl/*.c)
 HEADERS += $(wildcard src/gl/*.h)
 endif
 
+ifndef DISABLE_SW_RENDERER
+DEFINES += -DENABLE_SW_RENDERER
+SRCS += $(wildcard src/sw/*.c)
+HEADERS += $(wildcard src/sw/*.h)
+INCLUDES += -Isrc/sw
+endif
+
 ifdef DISABLE_WAD14
 ifdef DISABLE_WAD16
 ifdef DISABLE_WAD17
@@ -124,9 +137,11 @@ endif
 
 ifdef DISABLE_LEGACY_GL
 ifdef DISABLE_MODERN_GL
+ifdef DISABLE_SW_RENDERER
 $(error must enable at least 1 renderer)
 endif
 endif
+endif
 
 ifdef ENABLE_GLES
 DEFINES += -DENABLE_GLES

src/sw/defines.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "common.h"
+
+// CONFIG: Change the size of a pixel.
+//
+// 32-bit: 0xAARRGGBB
+// 16-bit: 0b0RRRRRGGGGGBBBBB
+// 8-bit:  0bBBGGGRRR
+#define PIXEL_SIZE 32
+//#define PIXEL_SIZE 16
+//#define PIXEL_SIZE 8
+
+#if defined(__GNUC__) && (__GNUC__ >= 3 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 96))
+#define LIKELY(cond)   __builtin_expect(!!(cond), 1)
+#define UNLIKELY(cond) __builtin_expect(!!(cond), 0)
+#else
+#define LIKELY(cond) (cond)
+#define UNLIKELY(cond) (cond)
+#endif
+
+#define UNUSED __attribute__ ((unused))
+#define FORCE_INLINE static inline __attribute__((always_inline))
+

src/sw/pixel_convert.h

@@ -0,0 +1,105 @@
+#pragma once
+
+#include "defines.h"
+#include "binary_utils.h"
+
+#if PIXEL_SIZE == 32
+typedef uint32_t uintpixel_t;
+#elif PIXEL_SIZE == 16
+typedef uint16_t uintpixel_t;
+#elif PIXEL_SIZE == 8
+typedef uint8_t uintpixel_t;
+#define PXL_TRANSPARENT (0xAA)
+#else
+#error "Unknown pixel size!"
+#endif
+
+// The native format coming out of GameMaker Studio's assets.
+typedef union
+{
+	struct {
+		uint8_t r, g, b, a;
+	} p;
+	uint32_t l;
+}
+Pixel32ABGR;
+
+// This is the format the renderer knows how to work with.
+typedef union
+{
+	struct {
+#ifdef IS_BIG_ENDIAN
+		uint8_t a, r, g, b;
+#else
+		uint8_t b, g, r, a;
+#endif
+	} p;
+	uint32_t l;
+}
+Pixel32ARGB;
+
+FORCE_INLINE UNUSED
+uint16_t abgr8888_to_rgb1555(uint32_t xl)
+{
+	Pixel32ABGR x;
+	x.l = xl;
+	return (x.p.b >> 3) | ((x.p.g >> 3) << 5) | ((x.p.r >> 3) << 10) | ((x.p.a >> 7) << 15);
+}
+
+FORCE_INLINE UNUSED
+uint8_t abgr8888_to_rgb332(uint32_t xl)
+{
+	Pixel32ABGR x;
+	x.l = xl;
+
+#if PIXEL_SIZE == 8
+	//check if transparent
+	if (x.p.a < 128)
+		return PXL_TRANSPARENT;
+#endif
+
+	uint8_t pxl = (x.p.r >> 5) | ((x.p.g >> 5) << 3) | ((x.p.b >> 6) << 6);
+
+#if PIXEL_SIZE == 8
+	//hacky fixup
+	if (pxl == PXL_TRANSPARENT)
+		pxl++;
+#endif
+
+	return pxl;
+}
+
+FORCE_INLINE UNUSED
+uintpixel_t swrConvertPixelBase(uint32_t gmPixel)
+{
+#if PIXEL_SIZE == 32
+	return (gmPixel & 0xFF00FF00) | ((gmPixel & 0xFF) << 16) | ((gmPixel >> 16) & 0xFF);
+#elif PIXEL_SIZE == 16
+	return abgr8888_to_rgb1555(gmPixel);
+#elif PIXEL_SIZE == 8
+	return abgr8888_to_rgb332(gmPixel);
+#endif
+}
+
+#if PIXEL_SIZE == 32
+#define TRANSPARENT_MASK 0xFF000000
+#elif PIXEL_SIZE == 16
+#define TRANSPARENT_MASK 0x8000
+#endif
+
+#if PIXEL_SIZE == 8
+
+#define swrConvertPixel(x)        swrConvertPixelBase((x) | 0xFF000000)
+#define swrConvertPixelTexture(x) swrConvertPixelBase(x)
+
+#elif defined IS_BIG_ENDIAN
+
+#define swrConvertPixel(x)        swrConvertPixelBase(x)
+#define swrConvertPixelTexture(x) swrConvertPixelBase(BinaryUtils_bswap32(x))
+
+#else
+
+#define swrConvertPixel        swrConvertPixelBase
+#define swrConvertPixelTexture swrConvertPixelBase
+
+#endif