Added RGBM encoding in GTC_packing #420

glm/gtc/packing.hpp

@@ -451,6 +451,8 @@ namespace glm
 	/// The first vector component specifies the 11 least-significant bits of the result; 
 	/// the last component specifies the 10 most-significant bits.
 	///
+	/// packF3x9_E1x5 allows encoding into RGBE / RGB9E5 format
+	///
 	/// @see gtc_packing
 	/// @see vec3 unpackF3x9_E1x5(uint32 const & p)
 	GLM_FUNC_DECL uint32 packF3x9_E1x5(vec3 const & v);
@@ -461,10 +463,33 @@ namespace glm
 	/// The first component of the returned vector will be extracted from the least significant bits of the input; 
 	/// the last component will be extracted from the most significant bits.
 	///
+	/// unpackF3x9_E1x5 allows decoding RGBE / RGB9E5 data
+	///
 	/// @see gtc_packing
 	/// @see uint32 packF3x9_E1x5(vec3 const & v)
 	GLM_FUNC_DECL vec3 unpackF3x9_E1x5(uint32 p);
 
+	/// Returns an unsigned integer vector obtained by converting the components of a floating-point vector
+	/// to the 16-bit floating-point representation found in the OpenGL Specification.
+	/// The first vector component specifies the 16 least-significant bits of the result; 
+	/// the forth component specifies the 16 most-significant bits.
+	/// 
+	/// @see gtc_packing
+	/// @see tvec3<T, P> unpackRGBM(tvec4<T, P> const & p)
+	/// @see <a href="http://www.opengl.org/registry/doc/GLSLangSpec.4.20.8.pdf">GLSL 4.20.8 specification, section 8.4 Floating-Point Pack and Unpack Functions</a>
+	template <typename T, precision P>
+	GLM_FUNC_DECL tvec4<T, P> packRGBM(tvec3<T, P> const & rgb);
+
+	/// Returns a floating-point vector with components obtained by reinterpreting an integer vector as 16-bit floating-point numbers and converting them to 32-bit floating-point values.
+	/// The first component of the vector is obtained from the 16 least-significant bits of v;
+	/// the forth component is obtained from the 16 most-significant bits of v.
+	/// 
+	/// @see gtc_packing
+	/// @see tvec4<T, P> packRGBM(tvec3<float, P> const & v)
+	/// @see <a href="http://www.opengl.org/registry/doc/GLSLangSpec.4.20.8.pdf">GLSL 4.20.8 specification, section 8.4 Floating-Point Pack and Unpack Functions</a>
+	template <typename T, precision P>
+	GLM_FUNC_DECL tvec3<T, P> unpackRGBM(tvec4<T, P> const & rgbm);
+
 	/// Returns an unsigned integer vector obtained by converting the components of a floating-point vector
 	/// to the 16-bit floating-point representation found in the OpenGL Specification.
 	/// The first vector component specifies the 16 least-significant bits of the result; 

glm/gtc/packing.inl

@@ -639,6 +639,22 @@ namespace detail
 		return vec3(Unpack.data.x, Unpack.data.y, Unpack.data.z) * pow(2.0f, Unpack.data.w - 15.f - 9.f);
 	}
 
+	// From http://graphicrants.blogspot.fr/2009/04/rgbm-color-encoding.html
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec4<T, P> packRGBM(tvec3<T, P> const & rgb)
+	{
+		tvec3<T, P> const Color(rgb * static_cast<T>(1.0 / 6.0));
+		T Alpha = clamp(max(max(Color.x, Color.y), max(Color.z, static_cast<T>(1e-6))), static_cast<T>(0), static_cast<T>(1));
+		Alpha = ceil(Alpha * static_cast<T>(255.0)) / static_cast<T>(255.0);
+		return tvec4<T, P>(Color / Alpha, Alpha);
+	}
+
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec3<T, P> unpackRGBM(tvec4<T, P> const & rgbm)
+	{
+		return tvec3<T, P>(rgbm.x, rgbm.y, rgbm.z) * rgbm.w * static_cast<T>(6);
+	}
+
 	template <precision P, template <typename, precision> class vecType>
 	GLM_FUNC_QUALIFIER vecType<uint16, P> packHalf(vecType<float, P> const & v)
 	{

readme.md

@@ -53,6 +53,7 @@ glm::mat4 camera(float Translate, glm::vec2 const & Rotate)
 
 #### [GLM 0.9.9.0](https://github.com/g-truc/glm/releases/latest) - 2017-XX-XX
 ##### Features:
+- Added RGBM encoding in GTC_packing #420
 - Added GTC_color_encoding extension
 
 ##### Improvements:

test/gtc/gtc_packing.cpp

@@ -251,6 +251,22 @@ int test_F3x9_E1x5()
 	return Error;
 }
 
+int test_RGBM()
+{
+	int Error = 0;
+
+	for(std::size_t i = 0; i < 1024; ++i)
+	{
+		glm::vec3 const Color(i);
+		glm::vec4 const RGBM = glm::packRGBM(Color);
+		glm::vec3 const Result= glm::unpackRGBM(RGBM);
+
+		Error += glm::all(glm::epsilonEqual(Color, Result, 0.01f)) ? 0 : 1;
+	}
+
+	return Error;
+}
+
 int test_packUnorm1x16()
 {
 	int Error = 0;
@@ -671,6 +687,7 @@ int main()
 
 	Error += test_F2x11_1x10();
 	Error += test_F3x9_E1x5();
+	Error += test_RGBM();
 	Error += test_Snorm3x10_1x2();
 	Error += test_Unorm3x10_1x2();
 	Error += test_I3x10_1x2();