From 8d6ed0b5fb02e2a2f9142e869fd705c36f57a225 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 12 Sep 2012 10:35:46 +0300
Subject: [PATCH] Support for anisotropic texture filtering

---
 source/ext_texture_filter_anisotropic.cpp | 18 ++++++++++++++++++
 source/ext_texture_filter_anisotropic.h   | 16 ++++++++++++++++
 source/texture.cpp                        | 19 +++++++++++++++++++
 source/texture.h                          |  7 ++++++-
 4 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 source/ext_texture_filter_anisotropic.cpp
 create mode 100644 source/ext_texture_filter_anisotropic.h

diff --git a/source/ext_texture_filter_anisotropic.cpp b/source/ext_texture_filter_anisotropic.cpp
new file mode 100644
index 00000000..e93249b0
--- /dev/null
+++ b/source/ext_texture_filter_anisotropic.cpp
@@ -0,0 +1,18 @@
+#include "ext_texture_filter_anisotropic.h"
+
+namespace Msp {
+namespace GL {
+
+Extension::SupportLevel init_ext_texture_filter_anisotropic()
+{
+	if(is_supported("GL_EXT_texture_filter_anisotropic"))
+	{
+		return Extension::EXTENSION;
+	}
+	return Extension::UNSUPPORTED;
+}
+
+Extension EXT_texture_filter_anisotropic("GL_EXT_texture_filter_anisotropic", init_ext_texture_filter_anisotropic);
+
+} // namespace GL
+} // namespace Msp
diff --git a/source/ext_texture_filter_anisotropic.h b/source/ext_texture_filter_anisotropic.h
new file mode 100644
index 00000000..be7f5b14
--- /dev/null
+++ b/source/ext_texture_filter_anisotropic.h
@@ -0,0 +1,16 @@
+#ifndef MSP_GL_EXT_TEXTURE_FILTER_ANISOTROPIC_
+#define MSP_GL_EXT_TEXTURE_FILTER_ANISOTROPIC_
+
+#include "extension.h"
+#include "gl.h"
+#include <GL/glext.h>
+
+namespace Msp {
+namespace GL {
+
+extern Extension EXT_texture_filter_anisotropic;
+
+} // namespace GL
+} // namespace Msp
+
+#endif
diff --git a/source/texture.cpp b/source/texture.cpp
index c8a1371c..e4d4ebf2 100644
--- a/source/texture.cpp
+++ b/source/texture.cpp
@@ -1,5 +1,6 @@
 #include <msp/strings/format.h>
 #include "error.h"
+#include "ext_texture_filter_anisotropic.h"
 #include "sgis_generate_mipmap.h"
 #include "texture.h"
 #include "texunit.h"
@@ -69,6 +70,8 @@ void Texture::update_parameter(int mask) const
 			glTexParameteri(target, GL_TEXTURE_MIN_FILTER, min_filter);
 		if(mask&MAG_FILTER)
 			glTexParameteri(target, GL_TEXTURE_MAG_FILTER, mag_filter);
+		if(mask&MAX_ANISOTROPY)
+			glTexParameteri(target, GL_TEXTURE_MAX_ANISOTROPY_EXT, max_anisotropy);
 		if(mask&WRAP_S)
 			glTexParameteri(target, GL_TEXTURE_WRAP_S, wrap_s);
 		if(mask&WRAP_T)
@@ -98,6 +101,16 @@ void Texture::set_mag_filter(TextureFilter f)
 	update_parameter(MAG_FILTER);
 }
 
+void Texture::set_max_anisotropy(float a)
+{
+	if(a<1.0f)
+		throw invalid_argument("Texture::set_max_anisotropy");
+	else if(a>1.0f)
+		static Require _req(EXT_texture_filter_anisotropic);
+	max_anisotropy = a;
+	update_parameter(MAX_ANISOTROPY);
+}
+
 void Texture::set_wrap(TextureWrap w)
 {
 	set_wrap_s(w);
@@ -196,6 +209,7 @@ void Texture::unbind_from(unsigned i)
 Texture::Loader::Loader(Texture &t):
 	DataFile::ObjectLoader<Texture>(t)
 {
+	add("max_anisotropy", &Loader::max_anisotropy);
 	add("generate_mipmap", &Loader::generate_mipmap);
 	add("mag_filter", &Loader::mag_filter);
 	add("min_filter", &Loader::min_filter);
@@ -215,6 +229,11 @@ void Texture::Loader::mag_filter(TextureFilter f)
 	obj.set_mag_filter(f);
 }
 
+void Texture::Loader::max_anisotropy(float a)
+{
+	obj.set_max_anisotropy(a);
+}
+
 void Texture::Loader::min_filter(TextureFilter f)
 {
 	obj.set_min_filter(f);
diff --git a/source/texture.h b/source/texture.h
index 30ad484c..af0844c5 100644
--- a/source/texture.h
+++ b/source/texture.h
@@ -70,8 +70,10 @@ protected:
 	{
 	public:
 		Loader(Texture &);
+	private:
 		void generate_mipmap(bool);
 		void mag_filter(TextureFilter);
+		void max_anisotropy(float);
 		void min_filter(TextureFilter);
 		void wrap(TextureWrap);
 		void wrap_r(TextureWrap);
@@ -88,13 +90,15 @@ protected:
 		WRAP_R = 16,
 		GENERATE_MIPMAP = 32,
 		COMPARE = 64,
-		COMPARE_FUNC = 128
+		COMPARE_FUNC = 128,
+		MAX_ANISOTROPY = 256
 	};
 
 	unsigned id;
 	GLenum target;
 	TextureFilter min_filter;
 	TextureFilter mag_filter;
+	float max_anisotropy;
 	TextureWrap wrap_s;
 	TextureWrap wrap_t;
 	TextureWrap wrap_r;
@@ -114,6 +118,7 @@ protected:
 public:
 	void set_min_filter(TextureFilter);
 	void set_mag_filter(TextureFilter);
+	void set_max_anisotropy(float);
 
 	/** Sets the wrapping mode for all coordinates. */
 	void set_wrap(TextureWrap);
-- 
2.43.0