Use #include "BLI_math.h" instead of _USE_MATH_DEFINES to get M_PI defined.

source/blender/blenkernel/intern/depsgraph.c

@@ -29,12 +29,9 @@
 #include <string.h>
 #include <math.h>
 
-#ifdef _WIN32
-#include "BLI_winstuff.h"
-#endif
-
 #include "BLI_blenlib.h"
 #include "BLI_math.h"
+#include "BLI_winstuff.h"
 
 #include "DNA_anim_types.h"
 #include "DNA_action_types.h"

source/blender/blenkernel/intern/unit.c

@@ -20,17 +20,13 @@
  *
  * ***** END GPL LICENSE BLOCK *****
  */
-#define _USE_MATH_DEFINES
-
 #include <stdlib.h>
 #include <stdio.h>
 #include <ctype.h>
 #include <string.h>
-#include <math.h>
 
-#if defined(WIN32) && (!(defined snprintf))
-#define snprintf _snprintf
-#endif
+#include "BLI_math.h"
+#include "BLI_winstuff.h"
 
 #define TEMP_STR_SIZE 256
 

source/blender/blenlib/BLI_winstuff.h

@@ -32,6 +32,8 @@
 #ifndef __WINSTUFF_H__
 #define __WINSTUFF_H__
 
+#ifdef _WIN32
+
 #ifndef FREE_WINDOWS
 #pragma warning(once: 4761 4305 4244 4018)
 #endif
@@ -139,5 +141,7 @@ int BLI_getInstallationDir(char *str);
 }
 #endif
 
+#endif
+
 #endif /* __WINSTUFF_H__ */
 

source/blender/editors/animation/anim_draw.c

@@ -28,7 +28,6 @@
  
 #include <string.h>
 #include <stdio.h>
-#include <math.h>
 
 #include "DNA_anim_types.h"
 #include "DNA_action_types.h"

source/blender/editors/mesh/loopcut.c

@@ -27,8 +27,6 @@
  */
 
 #include <float.h>
-#define _USE_MATH_DEFINES
-#include <math.h>
 #include <string.h>
 #include <ctype.h>
 #include <stdio.h>
@@ -47,6 +45,7 @@
 #include "BLI_blenlib.h"
 #include "BLI_dynstr.h" /*for WM_operator_pystring */
 #include "BLI_editVert.h"
+#include "BLI_math.h"
 
 #include "BKE_blender.h"
 #include "BKE_context.h"

source/blender/makesrna/intern/rna_brush.c

@@ -21,10 +21,8 @@
  *
  * ***** END GPL LICENSE BLOCK *****
  */
- #define _USE_MATH_DEFINES
 
 #include <stdlib.h>
-#include <math.h>
 
 #include "RNA_define.h"
 #include "RNA_types.h"
@@ -34,7 +32,10 @@
 #include "DNA_brush_types.h"
 #include "DNA_texture_types.h"
 
+#include "BLI_math.h"
+
 #include "IMB_imbuf.h"
+
 #include "WM_types.h"
 
 #ifdef RNA_RUNTIME

source/blender/makesrna/intern/rna_camera.c

@@ -22,9 +22,7 @@
  * ***** END GPL LICENSE BLOCK *****
  */
 
-#define _USE_MATH_DEFINES
 #include <stdlib.h>
-#include <math.h>
 
 #include "RNA_define.h"
 #include "RNA_types.h"
@@ -33,6 +31,8 @@
 
 #include "DNA_camera_types.h"
 
+#include "BLI_math.h"
+
 #include "WM_types.h"
 
 #ifdef RNA_RUNTIME

source/blender/makesrna/intern/rna_fcurve.c

@@ -22,10 +22,7 @@
  * ***** END GPL LICENSE BLOCK *****
  */
 
- #define _USE_MATH_DEFINES
- 
 #include <stdlib.h>
-#include <math.h>
 
 #include "RNA_access.h"
 #include "RNA_define.h"
@@ -40,6 +37,8 @@
 
 #include "MEM_guardedalloc.h"
 
+#include "BLI_math.h"
+
 #include "WM_types.h"
 
 EnumPropertyItem fmodifier_type_items[] = {

source/blender/windowmanager/intern/wm_gesture.c

@@ -26,9 +26,6 @@
  * ***** END GPL LICENSE BLOCK *****
  */
 
-#define _USE_MATH_DEFINES
-#include <math.h>
-
 #include "DNA_screen_types.h"
 #include "DNA_vec_types.h"
 #include "DNA_userdef_types.h"
@@ -38,6 +35,7 @@
 
 #include "BLI_blenlib.h"
 #include "BLI_editVert.h"	/* lasso tessellation */
+#include "BLI_math.h"
 #include "BLI_scanfill.h"	/* lasso tessellation */
 
 #include "BKE_context.h"

source/blender/windowmanager/intern/wm_operators.c

@@ -27,8 +27,6 @@
  */
 
 #include <float.h>
-#define _USE_MATH_DEFINES
-#include <math.h>
 #include <string.h>
 #include <ctype.h>
 #include <stdio.h>
@@ -48,6 +46,7 @@
 
 #include "BLI_blenlib.h"
 #include "BLI_dynstr.h" /*for WM_operator_pystring */
+#include "BLI_math.h"
 
 #include "BLO_readfile.h"