added glad generator and a glad runtime

tools/glad-0.1.14a0/glad/lang/nim/loader/gl.py

@@ -0,0 +1,147 @@
+from glad.lang.common.loader import BaseLoader
+from glad.lang.nim.loader import LOAD_OPENGL_DLL
+
+
+_OPENGL_LOADER = \
+    LOAD_OPENGL_DLL % {'pre':'private', 'init':'open_gl',
+                       'proc':'get_proc', 'terminate':'close_gl'} + '''
+bool gladLoadGL()
+    bool status = false
+
+    if(open_gl())
+        status = gladLoadGL(x => get_proc(x))
+        close_gl()
+
+    return status
+
+'''
+
+_OPENGL_HAS_EXT_LT3 = '''proc hasExt(extname: string): bool =
+  if extname == nil:
+    return false
+
+  var extensions = $cast[cstring](glGetString(GL_EXTENSIONS))
+  if extensions == nil:
+    return false
+
+  var
+    loc, terminatorLoc: int
+    terminator: char
+
+  while true:
+    loc = extensions.find(extname)
+    if loc < 0:
+      return false
+
+    terminatorLoc = loc + extname.len
+    terminator = extensions[terminatorLoc]
+
+    if (loc == 0 or extensions[loc - 1] == ' ') and
+       (terminator == ' ' or terminator == '\\0'):
+      return true
+
+    extensions = extensions[terminatorLoc..^1]
+
+
+'''
+
+_OPENGL_HAS_EXT_GTE3 = '''proc hasExt(extname: string): bool =
+  if extname == nil:
+    return false
+
+  if glVersionMajor < 3:
+    var extensions = $cast[cstring](glGetString(GL_EXTENSIONS))
+    if extensions == nil:
+      return false
+
+    var
+      loc, terminatorLoc: int
+      terminator: char
+
+    while true:
+      loc = extensions.find(extname)
+      if loc < 0:
+        return false
+
+      terminatorLoc = loc + extname.len
+      terminator = extensions[terminatorLoc]
+
+      if (loc == 0 or extensions[loc - 1] == ' ') and
+         (terminator == ' ' or terminator == '\\0'):
+        return true
+
+      extensions = extensions[terminatorLoc..^1]
+
+  else:
+    var
+      num: GLint
+      s: cstring
+
+    glGetIntegerv(GL_NUM_EXTENSIONS, num.addr)
+
+    for i in 0..num-1:
+      s = cast[cstring](glGetStringi(GL_EXTENSIONS, GLuint(i)))
+      if s == extname:
+        return true
+
+
+'''
+
+_FIND_VERSION = '''  # Thank you @elmindreda
+  # https://github.com/elmindreda/greg/blob/master/templates/greg.c.in#L176
+  # https://github.com/glfw/glfw/blob/master/src/context.c#L36
+  var prefixes = ["OpenGL ES-CM ", "OpenGL ES-CL ", "OpenGL ES "]
+
+  var version = glVersion
+  for p in prefixes:
+    if version.startsWith(p):
+      version = version.replace(p)
+      break
+
+  var major = ord(glVersion[0]) - ord('0')
+  var minor = ord(glVersion[2]) - ord('0')
+
+  glVersionMajor = major
+  glVersionMinor = minor
+
+'''
+
+_BEGIN_LOAD = '''  glGetString = cast[proc (name: GLenum): ptr GLubyte {.cdecl.}](load("glGetString"))
+  if glGetString == nil: return false
+
+  var glVersion = cast[cstring](glGetString(GL_VERSION))
+  if glVersion == nil: return false
+
+'''
+
+class OpenGLNimLoader(BaseLoader):
+    def write_header_end(self, fobj):
+        pass
+
+    def write_header(self, fobj):
+        pass
+
+    def write(self, fobj):
+        pass
+        # TODO
+#        if not self.disabled and 'gl' in self.apis:
+#            fobj.write(_OPENGL_LOADER)
+
+    def write_begin_load(self, fobj):
+        fobj.write(_BEGIN_LOAD)
+
+    def write_end_load(self, fobj):
+        fobj.write('\n  return glVersionMajor != 0 or glVersionMinor != 0\n')
+
+    def write_find_core(self, fobj):
+        fobj.write(_FIND_VERSION)
+
+    def write_has_ext(self, fobj, apiversion):
+        if apiversion.major == 1 and apiversion.minor == 0:
+            return
+        if apiversion.major < 3:
+            fobj.write(_OPENGL_HAS_EXT_LT3)
+        else:
+            fobj.write(_OPENGL_HAS_EXT_GTE3)
+
+