decompose stb headers into a submodule

Author: cobaltgit

.gitmodules

@@ -1,3 +1,6 @@
+[submodule "modules/third-party/stb"]
+	path = modules/third-party/stb
+	url = https://github.com/nothings/stb
 [submodule "third-party/dropbear"]
 	path = modules/third-party/dropbear
 	url = https://github.com/mkj/dropbear

modules/third-party/stb

@@ -1,16 +1,25 @@
 import std/os
 
-{.compile("stb_image.c", "-O3").}
-{.compile("stb_image_write.c", "-O3").}
-{.passC: "-I" & currentSourcePath().splitPath().head.}
+const StbDir = currentSourcePath().splitPath().head /
+  ".." / ".." / ".." / ".." /
+  "modules" / "third-party" / "stb"
+
+{.passC: "-O3 -I" & StbDir.}
+
+{.emit: """
+#define STB_IMAGE_IMPLEMENTATION
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image.h"
+#include "stb_image_write.h"
+""".}
 
 proc stbi_load*(
   filename: cstring,
   x: ptr cint,
   y: ptr cint,
   channels_in_file: ptr cint,
   desired_channels: cint
-): ptr uint8 {.importc, header: "stb_image.h".}
+): ptr uint8 {.importc, header: StbDir / "stb_image.h".}
 
 proc stbi_write_png*(
   filename: cstring,
@@ -19,6 +28,6 @@ proc stbi_write_png*(
   comp: cint,
   data: pointer,
   stride_in_bytes: cint
-): cint {.importc, header: "stb_image_write.h".}
+): cint {.importc, header: StbDir / "stb_image_write.h".}
 
-proc stbi_image_free*(data: pointer) {.importc, header: "stb_image.h".}
+proc stbi_image_free*(data: pointer) {.importc, header: StbDir / "stb_image.h".}