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@@ -74,6 +74,7 @@ The optional *manifests* folder of an extension contains additional files used i
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Extensions are treated just like any other assets in your project and they can be shared in the same way. If a native extension folder is added as a Library folder it can be shared and used by others as a project dependency. Refer to the [Library project manual](/manuals/libraries/) for more information.
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+
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## A simple example extension
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Let's build a very simple extension. First, we create a new root folder *myextension* and add a file *ext.manifest* containing the name of the extension "MyExtension". Note that the name is a C++ symbol and must match the first argument to `DM_DECLARE_EXTENSION` (see below).
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@@ -99,42 +100,27 @@ The extension source file contains the following code:
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// include the Defold SDK
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#include <dmsdk/sdk.h>
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-#include <stdlib.h>
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-static int Rot13(lua_State* L)
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+static int Reverse(lua_State* L)
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{
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- int top = lua_gettop(L);
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+ // The number of expected items to be on the Lua stack
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+ // once this struct goes out of scope
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+ DM_LUA_STACK_CHECK(L, 1);
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// Check and get parameter string from stack
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- const char* str = luaL_checkstring(L, 1);
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+ char* str = (char*)luaL_checkstring(L, 1);
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- // Allocate new string
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+ // Reverse the string
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int len = strlen(str);
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- char *rot = (char *) malloc(len + 1);
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-
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- // Iterate over the parameter string and create rot13 string
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- for(int i = 0; i <= len; i++) {
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- const char c = str[i];
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- if((c >= 'A' && c <= 'M') || (c >= 'a' && c <= 'm')) {
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- // Between A-M just add 13 to the char.
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- rot[i] = c + 13;
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- } else if((c >= 'N' && c <= 'Z') || (c >= 'n' && c <= 'z')) {
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- // If rolling past 'Z' which happens below 'M', wrap back (subtract 13)
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- rot[i] = c - 13;
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- } else {
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- // Leave character intact
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- rot[i] = c;
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- }
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+ for(int i = 0; i < len / 2; i++) {
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+ const char a = str[i];
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+ const char b = str[len - i - 1];
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+ str[i] = b;
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+ str[len - i - 1] = a;
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}
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- // Put the rotated string on the stack
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- lua_pushstring(L, rot);
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-
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- // Free string memory. Lua has a copy by now.
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- free(rot);
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-
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- // Assert that there is one item on the stack.
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- assert(top + 1 == lua_gettop(L));
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+ // Put the reverse string on the stack
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+ lua_pushstring(L, str);
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// Return 1 item
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return 1;
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@@ -143,7 +129,7 @@ static int Rot13(lua_State* L)
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// Functions exposed to Lua
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static const luaL_reg Module_methods[] =
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{
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- {"rot13", Rot13},
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+ {"reverse", Reverse},
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{0, 0}
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};
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@@ -199,12 +185,13 @@ To test the extension, create a game object and add a script component with some
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```lua
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local s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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-local rot_s = myextension.rot13(s)
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-print(rot_s) --> nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM
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+local reverse_s = myextension.reverse(s)
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+print(reverse_s) --> ZYXWVUTSRQPONMLKJIHGFEDCBAzyxwvutsrqponmlkjihgfedcba
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```
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And that's it! We have created a fully working native extension.
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+
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## Extension Lifecycle
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As we saw above the `DM_DECLARE_EXTENSION` macro is used to declare the various entry points into the extension code:
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@@ -240,6 +227,11 @@ The following identifiers are defined by the builder on each respective platform
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* DM_PLATFORM_LINUX
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* DM_PLATFORM_HTML5
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+## Build server logs
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+
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+Build server logs are available when the project is using native extensions. The build server log (`log.txt`) is downloaded together with the custom engine when the project is built and stored inside the file `.internal/%platform%/build.zip`.
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+
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+
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## The ext.manifest file
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Apart from the name of the extension, the manifest file can contain platform specific compile flags, link flags, libs and frameworks. If the *ext.manifest* file does not contain a "platforms" segment, or a platform is missing from the list, the platform you bundle for will still build, but without any extra flags set.
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Björn Ritzl