GLSLEffect.cs 4.23 KB
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

/* TODO:
 * * apply
 *   * HOW????
 *   * OnApply: protecteed internal :(
 *   * INTERNAL_applyEffect: internal...
 *     + calls mojoshader! --> hijack?!!
 *       -> glEffect{Begin,End}: state mgmt | unbind shader!
 *       -> glEffect{Begin,End}Pass: bind shader! | state mgmt
 *   * GD draw calls: ok
 *     * EXCEPT mojoshader: glProgramReady, glProgramViewportInfo
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 *       -> set up uniforms and vertex arrays!
 *       --> circumvent? --> HOW??
 *       --> just go with it?? --> glProgramReady ok, glProgramViewportInfo might segfault!
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 * * uniforms
 * * samplers, textures
 */

namespace PoroCYon.FNAGLSL {
	public class GLSLEffect : Effect {
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		public struct ActiveEffect : IDisposable {
			internal uint oldprgm;
			bool disposed;

			internal ActiveEffect(uint old) {
				oldprgm = old; disposed = false;
			}

			public void Dispose() {
				if (disposed) return;

				GL.UseProgram(oldprgm);
				oldprgm = 0;

				disposed = true;
			}
		}

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		uint[] glshdrs;
		uint glprgm;

		public unsafe GLSLEffect(GraphicsDevice gd,
					IDictionary<GLSLPurpose, string> shaders)
				: base(/*UGLY hack*/new BasicEffect(gd)) {
			GL.Init(gd);

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			// this basically makes FNA think this effect is a noop, so binding
			// this effect will do the same as binding the 0 program in OpenGL,
			// so the BasicEffect used won't do much anymore
			/*gd.DeleteEffect(this);
			eff.SetGLEffectData(IntPtr.Zero);
			eff.SetEffectData  (IntPtr.Zero);*/
			// turns out we can't do this, or libmojoshader will segfault
			// because it lacks some null checking in
			// glEffectEnd, glEffectBeginPass, glProgramViewportInfo :/ ...
			// so we basically have to make sure the usual route of Apply()ing
			// the shader happens (unless we can circumvent this *somehow*),
			// and then apply the shader manually.
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			var shdrs = new uint[shaders.Count];
			bool ok = false;
			uint prgm = 0;

			try {
				prgm = GL.CreateProgram();
				if (prgm == 0) GL.Throw();

				int i = 0;
				foreach (var kvp in shaders) {
					uint sh = GL.CreateShader(kvp.Key);
					if (sh == 0) GL.Throw();

					byte[] utf8src = Encoding.UTF8.GetBytes(kvp.Value);
					fixed (byte* sbuf = utf8src) {
						sbyte** uurgh = stackalloc sbyte*[1];
						*uurgh = (sbyte*)sbuf;
						int* uurgh2 = stackalloc int[1];
						*uurgh2 = utf8src.Length;
						GL.ShaderSource(sh, 1, uurgh, uurgh2);
					}
					GL.Throw();

					GL.CompileShader(sh);

					if (GL.GetError() != 0 || GL.GetShaderiv(sh, GL.COMPILE_STATUS) == 0) {
						int len = GL.GetShaderiv(sh, GL.INFO_LOG_LENGTH);
						var msg = new sbyte[len];
						fixed (sbyte* buf = msg) {
							GL.GetShaderInfoLog(sh, len, null, buf);
							throw new GLSLCompileException(new String(buf, 0, len-1));
						}
					}

					GL.AttachShader(prgm, sh);
					GL.Throw();

					shdrs[i++] = sh;
				}

				GL.LinkProgram(prgm);
				if (GL.GetError() != 0 || GL.GetProgramiv(prgm, GL.LINK_STATUS) == 0) {
					int len = GL.GetProgramiv(prgm, GL.INFO_LOG_LENGTH);
					var msg = new sbyte[len];
					fixed (sbyte* buf = msg) {
						GL.GetProgramInfoLog(prgm, len, null, buf);
						throw new GLSLLinkException(new String(buf, 0, len-1));
					}
				}

				ok = true;
			}
			finally {
				if (!ok) {
					DelShdrPrgm();
				} else {
					glshdrs = shdrs;
					glprgm  = prgm ;
				}
			}
		}

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		// TODO: find out a better (i.e. more API-conform) way to do this!
		///<summary>
		///USAGE: using (var eff &eq; glslEffect.Bind()) { ... gd.DrawPrimitives(...); ... }
		///</summary>
		public ActiveEffect Bind() {
			uint oldprgm = unchecked((uint)GL.GetIntegerv(GL.CURRENT_PROGRAM));
			GL.Throw();

			GL.UseProgram(glprgm);
			GL.Throw();

			// TODO: apply uniforms and samplers! (XNA API -> OpenGL state)

			return new ActiveEffect(oldprgm);
		}
		[Obsolete("Please use Bind() instead")]
		public ActiveEffect Apply() { return Bind(); }

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		void DelShdrPrgm() {
			for (int i = 0; i < glshdrs.Length; ++i)
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				if (glshdrs[i] != 0)
					GL.DeleteShader(glshdrs[i]);
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			if (glprgm != 0)
				GL.DeleteProgram(glprgm);
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		}

		protected override void Dispose(bool disposing) {
			if (!IsDisposed) {
				DelShdrPrgm();
			}

			base.Dispose(disposing);
		}
	}
}