From 107929eae003ba53d2cf9a5982bbc56966f5ab42 Mon Sep 17 00:00:00 2001
From: Ketmar Dark <ketmar@ketmar.no-ip.org>
Date: Fri, 5 Feb 2016 01:50:48 +0200
Subject: [PATCH] lazy ogl function loading

---
 glbinds.d | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 50 insertions(+), 9 deletions(-)

diff --git a/glbinds.d b/glbinds.d
index 3b6b6a3..be528ff 100644
--- a/glbinds.d
+++ b/glbinds.d
@@ -1,5 +1,12 @@
 module glbinds;
 
+// lazy loading
+version = glbind_lazy_load;
+
+// show loaded functions
+//version = glbind_debug;
+
+
 static if (__traits(compiles, () { import arsd.simpledisplay; })) {
   public import arsd.simpledisplay;
 } else {
@@ -151,21 +158,55 @@ alias glbfn_glGetIntegerv = void function (GLenum, GLint*);
 
 
 // ////////////////////////////////////////////////////////////////////////// //
-private string glbindCreateInternalVars () {
-  string res;
-  foreach (name; __traits(allMembers, mixin(__MODULE__))) {
-    static if (name.length > 6 && name[0..6] == "glbfn_") {
-      //pragma(msg, name);
-      // create pointer
-      res ~= "__gshared "~name~" "~name[6..$]~";\n";
+version(glbind_lazy_load) {
+  private string glbindCreateInternalVars () {
+    string res;
+    foreach (name; __traits(allMembers, mixin(__MODULE__))) {
+      static if (name.length > 6 && name[0..6] == "glbfn_") {
+        //pragma(msg, mixin(name));
+        import std.traits;
+        //pragma(msg, ReturnType!(mixin(name)));
+        //pragma(msg, Parameters!(mixin(name)));
+        // create pointer
+        string pars, call;
+        foreach (immutable idx, immutable ptype; Parameters!(mixin(name))) {
+          import std.conv : to;
+          pars ~= ", "~ptype.stringof~" a"~to!string(idx);
+          call ~= "a"~to!string(idx)~",";
+        }
+        if (pars.length) pars = pars[2..$];
+        res ~= "__gshared "~name~" "~name[6..$]~" = function "~
+          ReturnType!(mixin(name)).stringof~" "~
+          /*Parameters!(mixin(name)).stringof*/"("~pars~") nothrow{\n"~
+          // build loader
+          "  "~name[6..$]~" = cast("~name~")glGetProcAddress(`"~name[6..$]~"`);\n"~
+          "  if ("~name[6..$]~" is null) assert(0, `OpenGL function '"~name[6..$]~"' not found!`);\n"~
+          "  version(glbind_debug) { import core.stdc.stdio; fprintf(stderr, \"GLBIND: '"~name[6..$]~"'\\n\"); }\n"~
+          "  "~(is(ReturnType!(mixin(name)) == void) ? "" : "return ")~name[6..$]~"("~call~");\n"~
+          //"  assert(0, `"~name[6..$]~"`);\n"~
+          "};\n";
+      }
     }
+    return res;
+  }
+} else {
+  private string glbindCreateInternalVars () {
+    string res;
+    foreach (name; __traits(allMembers, mixin(__MODULE__))) {
+      static if (name.length > 6 && name[0..6] == "glbfn_") {
+        //pragma(msg, name);
+        // create pointer
+        res ~= "__gshared "~name~" "~name[6..$]~";\n";
+      }
+    }
+    return res;
   }
-  return res;
 }
 mixin(glbindCreateInternalVars());
 
 
 public void glbindLoadFunctions () {
+  version(glbind_lazy_load) {} else {
   foreach (name; __traits(allMembers, mixin(__MODULE__))) {
     static if (name.length > 6 && name[0..6] == "glbfn_") {
       //pragma(msg, name);
@@ -174,7 +215,7 @@ public void glbindLoadFunctions () {
       mixin("if ("~name[6..$]~" is null) assert(0, `OpenGL function '"~name[6..$]~"' not found!`);");
     }
   }
-  //assert(0, "boo");
+  }
 }
 
 
-- 
2.11.4.GIT