Opentk/Source/OpenTK/OpenGL/GLHelper.cs
2007-08-01 09:30:14 +00:00

476 lines
20 KiB
C#

#region --- License ---
/* Copyright (c) 2006, 2007 Stefanos Apostolopoulos
* See license.txt for license info
*/
#endregion
#region --- Using Directives ---
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Reflection;
#endregion
[assembly: CLSCompliant(true)]
namespace OpenTK.OpenGL
{
/// <summary>
/// OpenGL binding for .NET, implementing OpenGL 2.1, plus extensions.
/// </summary>
/// <remarks>
/// <para>
/// OpenTK.OpenGL.GL contains all OpenGL enums and functions defined in the 2.1 specification.
/// The official .spec files can be found at: http://opengl.org/registry/.
/// </para>
/// <para>
/// OpenTK.OpenGL.GL relies on static initialization to obtain the entry points for OpenGL functions.
/// Please ensure that a valid OpenGL context has been made current in the pertinent thread <b>before</b>
/// any OpenGL functions are called (toolkits like GLUT, SDL or GLFW will automatically take care of
/// the context initialization process). Without a valid OpenGL context, OpenTK.OpenGL.GL will only be able
/// to retrieve statically exported entry points (typically corresponding to OpenGL version 1.1 under Windows,
/// 1.3 under Linux and 1.4 under Windows Vista), and extension methods will need to be loaded manually.
/// </para>
/// <para>
/// If you prefer not to rely on static initialisation for the Gl class, you can use the
/// ReloadFunctions or ReloadFunction methods to manually force the initialisation of OpenGL entry points.
/// The ReloadFunctions method should be called whenever you change an existing visual or pixelformat. This
/// generally happens when you change the color/stencil/depth buffer associated with a window (but probably
/// not the resolution). This may or may not be necessary under Linux/MacOS, but is generally required for
/// Windows.
/// </para>
/// <para>
/// You can use the Gl.IsExtensionSupported method to check whether any given category of extension functions
/// exists in the current OpenGL context. The results can be cached to speed up future searches.
/// Keep in mind that different OpenGL contexts may support different extensions, and under different entry
/// points. Always check if all required extensions are still supported when changing visuals or pixel
/// formats.
/// </para>
/// <para>
/// You may retrieve the entry point for an OpenGL extension using the Gl.GetDelegateForExtensionMethod
/// and Gl.GetFunctionPointerForExtensionMethod methods. You may retrieve the entry point for an OpenGL
/// function using the Gl.GetDelegateForMethod method. All three methods are cross-platform.
/// </para>
/// <para>
/// <see href="http://opengl.org/registry/"/>
/// <seealso cref="Gl.IsExtensionSupported(string, bool)"/>
/// <seealso cref="Gl.GetDelegateForExtensionMethod"/>
/// <seealso cref="Gl.GetFunctionPointerForExtensionMethod"/>
/// <seealso cref="Gl.GetDelegateForMethod"/>
/// <seealso cref="Gl.ReloadFunctions"/>
/// <seealso cref="Gl.ReloadFunction"/>
/// </para>
/// </remarks>
public static partial class GL
{
#region internal string Library
internal const string Library = "opengl32.dll";
#endregion
#region private enum Platform
/// <summary>
/// Enumerates the platforms OpenTK can run on.
/// </summary>
private enum Platform
{
Unknown,
Windows,
X11,
X11_ARB,
OSX
};
#endregion private enum Platform
private static Platform platform = Platform.Unknown;
private static System.Collections.Generic.Dictionary<string, bool> AvailableExtensions;
#region internal static extern IntPtr glxGetProcAddressARB(string s);
// also linux, for our ARB-y friends
[DllImport(Library, EntryPoint = "glXGetProcAddressARB")]
internal static extern IntPtr glxGetProcAddressARB(string s);
#endregion
#region internal static IntPtr aglGetProcAddress(string s)
// osx gets complicated
[DllImport("libdl.dylib", EntryPoint = "NSIsSymbolNameDefined")]
internal static extern bool NSIsSymbolNameDefined(string s);
[DllImport("libdl.dylib", EntryPoint = "NSLookupAndBindSymbol")]
internal static extern IntPtr NSLookupAndBindSymbol(string s);
[DllImport("libdl.dylib", EntryPoint = "NSAddressOfSymbol")]
internal static extern IntPtr NSAddressOfSymbol(IntPtr symbol);
internal static IntPtr aglGetProcAddress(string s)
{
string fname = "_" + s;
if (!NSIsSymbolNameDefined(fname))
return IntPtr.Zero;
IntPtr symbol = NSLookupAndBindSymbol(fname);
if (symbol != IntPtr.Zero)
symbol = NSAddressOfSymbol(symbol);
return symbol;
}
#endregion
#region public static IntPtr GetFunctionPointerForExtensionMethod(string name)
/// <summary>
/// Retrieves the entry point for a dynamically exported OpenGL function.
/// </summary>
/// <param name="name">The function string for the OpenGL function (eg. "glNewList")</param>
/// <returns>
/// An IntPtr contaning the address for the entry point, or IntPtr.Zero if the specified
/// OpenGL function is not dynamically exported.
/// </returns>
/// <remarks>
/// <para>
/// The Marshal.GetDelegateForFunctionPointer method can be used to turn the return value
/// into a call-able delegate.
/// </para>
/// <para>
/// This function is cross-platform. It determines the underlying platform and uses the
/// correct wgl, glx or agl GetAddress function to retrieve the function pointer.
/// </para>
/// <see cref="Marshal.GetDelegateForFunctionPointer"/>
/// <seealso cref="Gl.GetDelegateForExtensionMethod"/>
/// </remarks>
public static IntPtr GetFunctionPointerForExtensionMethod(string name)
{
IntPtr result = IntPtr.Zero;
switch (platform)
{
case Platform.Unknown:
// WGL?
try
{
result = OpenTK.Platform.Windows.Wgl.GetProcAddress(name);
platform = Platform.Windows;
return result;
}
catch (Exception)
{ }
// AGL? (before X11, since GLX might exist on OSX)
try
{
result = aglGetProcAddress(name);
platform = Platform.OSX;
return result;
}
catch (Exception)
{ }
// X11?
try
{
result = OpenTK.Platform.X11.Glx.GetProcAddress(name);
platform = Platform.X11;
return result;
}
catch (Exception)
{ }
// X11 ARB?
try
{
result = glxGetProcAddressARB(name);
platform = Platform.X11_ARB;
return result;
}
catch (Exception)
{ }
// Ack!
throw new NotSupportedException(
@"Could not find out how to retrive function pointers for this platform.
Did you remember to copy OpenTK.OpenGL.dll.config to your binary's folder?
");
case Platform.Windows:
return OpenTK.Platform.Windows.Wgl.GetProcAddress(name);
case Platform.OSX:
return aglGetProcAddress(name);
case Platform.X11:
return OpenTK.Platform.X11.Glx.GetProcAddress(name);
case Platform.X11_ARB:
return glxGetProcAddressARB(name);
}
throw new NotSupportedException("Internal error - please report.");
}
#endregion public static IntPtr GetFunctionPointerForExtensionMethod(string s)
#region public static Delegate GetDelegateForExtensionMethod(string name, Type signature)
/// <summary>
/// Creates a System.Delegate that can be used to call a dynamically exported OpenGL function.
/// </summary>
/// <param name="name">The name of the OpenGL function (eg. "glNewList")</param>
/// <param name="signature">The signature of the OpenGL function.</param>
/// <returns>
/// A System.Delegate that can be used to call this OpenGL function or null
/// if the function is not available in the current OpenGL context.
/// </returns>
public static Delegate GetDelegateForExtensionMethod(string name, Type signature)
{
IntPtr address = GetFunctionPointerForExtensionMethod(name);
if (address == IntPtr.Zero ||
address == new IntPtr(1) || // Workaround for buggy nvidia drivers which return
address == new IntPtr(2)) // 1 or 2 instead of IntPtr.Zero for some extensions.
{
return null;
}
else
{
return Marshal.GetDelegateForFunctionPointer(address, signature);
}
}
#endregion public static Delegate GetAddress(string name, Type signature)
#region public static Delegate GetDelegateForMethod(string name, Type signature)
/// <summary>
/// Creates a System.Delegate that can be used to call an OpenGL function, core or extension.
/// </summary>
/// <param name="name">The name of the OpenGL function (eg. "glNewList")</param>
/// <param name="signature">The signature of the OpenGL function.</param>
/// <returns>
/// A System.Delegate that can be used to call this OpenGL function, or null if the specified
/// function name did not correspond to an OpenGL function.
/// </returns>
public static Delegate GetDelegateForMethod(string name, Type signature)
{
Delegate d;
if (Assembly.GetExecutingAssembly()
.GetType("OpenTK.OpenGL.Imports")
.GetMethod(name.Substring(2), BindingFlags.NonPublic | BindingFlags.Static) != null)
{
d = GetDelegateForExtensionMethod(name, signature) ??
Delegate.CreateDelegate(signature, typeof(Imports), name.Substring(2));
}
else
{
d = GetDelegateForExtensionMethod(name, signature);
}
return d;
}
#endregion
#region public static bool IsExtensionSupported(string name)
/// <summary>
/// Determines whether the specified OpenGL extension category is available in
/// the current OpenGL context. Equivalent to IsExtensionSupported(name, true)
/// </summary>
/// <param name="name">The string for the OpenGL extension category (eg. "GL_ARB_multitexture")</param>
/// <returns>True if the specified extension is available, false otherwise.</returns>
public static bool IsExtensionSupported(string name)
{
return IsExtensionSupported(name, true);
}
#endregion
#region public static bool IsExtensionSupported(string name, bool useCache)
/// <summary>
/// Determines whether the specified OpenGL extension category is available in
/// the current OpenGL context.
/// </summary>
/// <param name="name">The string for the OpenGL extension category (eg. "GL_ARB_multitexture")</param>
/// <param name="useCache">If true, the results will be cached to speed up future results.</param>
/// <returns>True if the specified extension is available, false otherwise.</returns>
public static bool IsExtensionSupported(string name, bool useCache)
{
// Use cached results
if (useCache)
{
// Build cache if it is not available
if (AvailableExtensions == null)
{
ParseAvailableExtensions();
}
// Search the cache for the string. Note that the cache substitutes
// strings "1.0" to "2.1" with "GL_VERSION_1_0" to "GL_VERSION_2_1"
if (AvailableExtensions.ContainsKey(name))
return AvailableExtensions[name];
else
return false;
}
// Do not use cached results
string extension_string = GL.GetString(GL.Enums.StringName.EXTENSIONS);
if (String.IsNullOrEmpty(extension_string))
return false; // no extensions are available
// Check if the user searches for GL_VERSION_X_X and search glGetString(GL_VERSION) instead.
if (name.Contains("GL_VERSION_"))
{
return GL.GetString(OpenTK.OpenGL.GL.Enums.StringName.VERSION).Trim().StartsWith(name.Replace("GL_VERSION_", String.Empty).Replace('_', '.'));
}
// Search for the string given.
string[] extensions = extension_string.Split(' ');
foreach (string s in extensions)
{
if (name == s)
return true;
}
return false;
}
#endregion
#region private static void ParseAvailableExtensions()
/// <summary>
/// Builds a cache of the supported extensions to speed up searches.
/// </summary>
private static void ParseAvailableExtensions()
{
// Assumes there is a current context.
AvailableExtensions = new Dictionary<string, bool>();
string version_string = GL.GetString(OpenTK.OpenGL.GL.Enums.StringName.VERSION);
if (String.IsNullOrEmpty(version_string))
return; // this shoudn't happen
string version = version_string.Trim(' ');
if (version.StartsWith("1.2"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
}
else if (version.StartsWith("1.3"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
AvailableExtensions.Add("GL_VERSION_1_3", true);
}
else if (version.StartsWith("1.4"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
AvailableExtensions.Add("GL_VERSION_1_3", true);
AvailableExtensions.Add("GL_VERSION_1_4", true);
}
else if (version.StartsWith("1.5"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
AvailableExtensions.Add("GL_VERSION_1_3", true);
AvailableExtensions.Add("GL_VERSION_1_4", true);
AvailableExtensions.Add("GL_VERSION_1_5", true);
}
else if (version.StartsWith("2.0"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
AvailableExtensions.Add("GL_VERSION_1_3", true);
AvailableExtensions.Add("GL_VERSION_1_4", true);
AvailableExtensions.Add("GL_VERSION_1_5", true);
AvailableExtensions.Add("GL_VERSION_2_0", true);
}
else if (version.StartsWith("2.1"))
{
AvailableExtensions.Add("GL_VERSION_1_2", true);
AvailableExtensions.Add("GL_VERSION_1_3", true);
AvailableExtensions.Add("GL_VERSION_1_4", true);
AvailableExtensions.Add("GL_VERSION_1_5", true);
AvailableExtensions.Add("GL_VERSION_2_0", true);
AvailableExtensions.Add("GL_VERSION_2_1", true);
}
string extension_string = GL.GetString(OpenTK.OpenGL.GL.Enums.StringName.EXTENSIONS);
if (String.IsNullOrEmpty(extension_string))
return; // no extensions are available
string[] extensions = extension_string.Split(' ');
foreach (string ext in extensions)
{
AvailableExtensions.Add(ext, true);
}
}
#endregion
#region public static void ReloadFunctions()
/// <summary>
/// Reloads all OpenGL functions (core and extensions).
/// </summary>
/// <remarks>
/// <para>
/// Call this function to reload all OpenGL entry points. This should be done
/// whenever you change the pixelformat/visual, or in the case you cannot (or do not want)
/// to use the automatic initialisation.
/// </para>
/// <para>
/// Calling this function before the automatic initialisation has taken place will result
/// in the Gl class being initialised twice. This is harmless, but given the automatic
/// initialisation should be preferred.
/// </para>
/// </remarks>
public static void ReloadFunctions()
{
Assembly asm = Assembly.GetExecutingAssembly();//Assembly.Load("OpenTK.OpenGL");
Type delegates_class = asm.GetType("OpenTK.OpenGL.Delegates");
Type imports_class = asm.GetType("OpenTK.OpenGL.Imports");
FieldInfo[] v = delegates_class.GetFields(BindingFlags.Static | BindingFlags.NonPublic);
foreach (FieldInfo f in v)
{
f.SetValue(null, GetDelegateForMethod(f.Name, f.FieldType));
}
ParseAvailableExtensions();
}
#endregion
#region public static bool ReloadFunction(string name)
/// <summary>
/// Tries to reload the given OpenGL function (core or extension).
/// </summary>
/// <param name="name">The name of the OpenGL function (i.e. glShaderSource)</param>
/// <returns>True if the function was found and reloaded, false otherwise.</returns>
/// <remarks>
/// <para>
/// Use this function if you require greater granularity when loading OpenGL entry points.
/// </para>
/// <para>
/// While the automatic initialisation will load all OpenGL entry points, in some cases
/// the initialisation can take place before an OpenGL Context has been established.
/// In this case, use this function to load the entry points for the OpenGL functions
/// you will need, or use ReloadFunctions() to load all available entry points.
/// </para>
/// <para>
/// This function will return true if the given OpenGL function exists, false otherwise.
/// A return value of "true" does not mean that any specific OpenGL function is supported;
/// rather it means that the string passed to this function denotes a known OpenGL function.
/// </para>
/// <para>
/// To query supported extensions use the IsExtensionSupported() function instead.
/// </para>
/// </remarks>
public static bool ReloadFunction(string name)
{
Assembly asm = Assembly.Load("OpenTK.OpenGL");
Type delegates_class = asm.GetType("OpenTK.OpenGL.Delegates");
Type imports_class = asm.GetType("OpenTK.OpenGL.Imports");
FieldInfo f = delegates_class.GetField(name);
if (f == null)
return false;
f.SetValue(null, GetDelegateForMethod(f.Name, f.FieldType));
return true;
}
#endregion
}
}