user_constants.h is now unused by default

CMakeLists.txt

@@ -15,8 +15,12 @@ project(box2d
 # message(STATUS "CMake C++ compiler: ${CMAKE_CXX_COMPILER_ID}")
 message(STATUS "CMake system name: ${CMAKE_SYSTEM_NAME}")
 
-set(BOX2D_LENGTH_UNIT_PER_METER "1.0" CACHE STRING "Length units per meter")
-set(BOX2D_MAX_POLYGON_VERTICES "8" CACHE STRING "Maximum number of polygon vertices (affects performance)")
+option(BOX2D_USER_CONSTANTS "Generate user_constants.h" OFF)
+
+if (BOX2D_USER_CONSTANTS)
+	set(BOX2D_LENGTH_UNIT_PER_METER "1.0" CACHE STRING "Length units per meter")
+	set(BOX2D_MAX_POLYGON_VERTICES "8" CACHE STRING "Maximum number of polygon vertices (affects performance)")
+endif()
 
 # Needed for samples.exe to find box2d.dll
 # set(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/bin")

include/box2d/constants.h

@@ -12,14 +12,14 @@
 ///	Although most of these are not user configurable, it can be interesting for a user to see
 ///	these to understand the tuning values Box2D uses.
 
-// todo move constraint hertz/damping here
-
-#include "user_constants.h"
+#ifdef BOX2D_USER_CONSTANTS
+	#include "user_constants.h"
+#endif
 
 /// box2d bases all length units on meters, but you may need different units for your game.
 /// You can override this value to use different units.
 #ifndef b2_lengthUnitsPerMeter
-#define b2_lengthUnitsPerMeter 1.0f
+	#define b2_lengthUnitsPerMeter 1.0f
 #endif
 
 /// https://en.wikipedia.org/wiki/Pi
@@ -44,7 +44,7 @@
 /// The maximum number of vertices on a convex polygon. Changing this affects performance even if you
 ///	don't use more vertices.
 #ifndef b2_maxPolygonVertices
-#define b2_maxPolygonVertices 8
+	#define b2_maxPolygonVertices 8
 #endif
 
 /// Maximum number of simultaneous worlds that can be allocated

include/box2d/types.h

@@ -19,21 +19,18 @@
 #include <stddef.h>
 #include <stdint.h>
 
+// clang-format off
 #ifdef __cplusplus
-#define B2_LITERAL(T) T
-#define B2_ZERO_INIT                                                                                                             \
-	{                                                                                                                            \
-	}
+	#define B2_LITERAL(T) T
+	#define B2_ZERO_INIT {}
 #else
-/// Used for C literals like (b2Vec2){1.0f, 2.0f} where C++ requires b2Vec2{1.0f, 2.0f}
-#define B2_LITERAL(T) (T)
-
-/// Used for C zero initialization, such as b2Vec2 v = {0} where C++ requires b2Vec2 v = {}
-#define B2_ZERO_INIT                                                                                                             \
-	{                                                                                                                            \
-		0                                                                                                                        \
-	}
+	/// Used for C literals like (b2Vec2){1.0f, 2.0f} where C++ requires b2Vec2{1.0f, 2.0f}
+	#define B2_LITERAL(T) (T)
+
+	/// Used for C zero initialization, such as b2Vec2 v = {0} where C++ requires b2Vec2 v = {}
+	#define B2_ZERO_INIT {0}
 #endif
+// clang-format on
 
 /// Returns the number of elements of an array
 #define B2_ARRAY_COUNT(A) (int)(sizeof(A) / sizeof(A[0]))

src/CMakeLists.txt

@@ -1,5 +1,3 @@
-configure_file(user_constants.h.in user_constants.h)
-
 set(BOX2D_SOURCE_FILES
 	aabb.c
 	aabb.h
@@ -87,6 +85,12 @@ set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
 
 add_library(box2d ${BOX2D_SOURCE_FILES} ${BOX2D_API_FILES})
 
+if (BOX2D_USER_CONSTANTS)
+	# this file allows users to override constants
+	configure_file(user_constants.h.in user_constants.h)
+	target_compile_definitions(box2d PUBLIC BOX2D_USER_CONSTANTS)
+endif()
+
 # Generate box2d_export.h to handles shared library builds
 # turned this off to make Box2D easier to use without cmake
 # include(GenerateExportHeader)