Fixed and tested pack/unpackSnorm4x8 functions

glm/core/func_packing.inl

@@ -78,24 +78,15 @@ GLM_FUNC_QUALIFIER detail::tvec2<detail::float32> unpackSnorm2x16(detail::uint32
 
 GLM_FUNC_QUALIFIER detail::uint32 packUnorm4x8(detail::tvec4<detail::float32> const & v)
 {
-		detail::uint8 A((detail::uint8)round(clamp(v.x, 0.0f, 1.0f) * 255.0f));
-		detail::uint8 B((detail::uint8)round(clamp(v.y, 0.0f, 1.0f) * 255.0f));
-		detail::uint8 C((detail::uint8)round(clamp(v.z, 0.0f, 1.0f) * 255.0f));
-		detail::uint8 D((detail::uint8)round(clamp(v.w, 0.0f, 1.0f) * 255.0f));
-		return detail::uint32((D << 24) | (C << 16) | (B << 8) | A);
-}
-
-GLM_FUNC_QUALIFIER detail::uint32 packSnorm4x8(detail::tvec4<detail::float32> const & v)
-{
-		detail::uint8 A((detail::uint8)round(clamp(v.x,-1.0f, 1.0f) * 255.0f));
-		detail::uint8 B((detail::uint8)round(clamp(v.y,-1.0f, 1.0f) * 255.0f));
-		detail::uint8 C((detail::uint8)round(clamp(v.z,-1.0f, 1.0f) * 255.0f));
-		detail::uint8 D((detail::uint8)round(clamp(v.w,-1.0f, 1.0f) * 255.0f));
-		return detail::uint32((D << 24) | (C << 16) | (B << 8) | A);
+	detail::uint8 A((detail::uint8)round(clamp(v.x, 0.0f, 1.0f) * 255.0f));
+	detail::uint8 B((detail::uint8)round(clamp(v.y, 0.0f, 1.0f) * 255.0f));
+	detail::uint8 C((detail::uint8)round(clamp(v.z, 0.0f, 1.0f) * 255.0f));
+	detail::uint8 D((detail::uint8)round(clamp(v.w, 0.0f, 1.0f) * 255.0f));
+	return detail::uint32((D << 24) | (C << 16) | (B << 8) | A);
 }
 
 GLM_FUNC_QUALIFIER detail::tvec4<detail::float32> unpackUnorm4x8(detail::uint32 const & p)
-{
+{	
 	detail::uint8 A(detail::uint8(p >> 0));
 	detail::uint8 B(detail::uint8(p >> 8));
 	detail::uint8 C(detail::uint8(p >> 16));
@@ -106,18 +97,40 @@ GLM_FUNC_QUALIFIER detail::tvec4<detail::float32> unpackUnorm4x8(detail::uint32
 		C * 1.0f / 255.0f,
 		D * 1.0f / 255.0f);
 }
+	
+GLM_FUNC_QUALIFIER detail::uint32 packSnorm4x8(detail::tvec4<detail::float32> const & v)
+{
+	union iu
+	{
+		detail::int8 i;
+		detail::uint8 u;
+	} A, B, C, D;
+	
+	detail::tvec4<detail::float32> Unpack = clamp(v ,-1.0f, 1.0f) * 127.0f;
+	A.i = detail::int8(round(Unpack.x));
+	B.i = detail::int8(round(Unpack.y));
+	C.i = detail::int8(round(Unpack.z));
+	D.i = detail::int8(round(Unpack.w));
+	detail::uint32 Pack = (detail::uint32(D.u) << 24) | (detail::uint32(C.u) << 16) | (detail::uint32(B.u) << 8) | (detail::uint32(A.u) << 0);
+	return Pack;
+}
 
 GLM_FUNC_QUALIFIER detail::tvec4<detail::float32> unpackSnorm4x8(detail::uint32 const & p)
 {
-	detail::uint8 A(detail::uint8(p >> 0));
-	detail::uint8 B(detail::uint8(p >> 8));
-	detail::uint8 C(detail::uint8(p >> 16));
-	detail::uint8 D(detail::uint8(p >> 24));
-	return clamp(detail::tvec4<detail::float32>(
-		A * 1.0f / 127.0f, 
-		B * 1.0f / 127.0f,
-		C * 1.0f / 127.0f,
-		D * 1.0f / 127.0f), -1.0f, 1.0f);
+	union iu
+	{
+		detail::int8 i;
+		detail::uint8 u;
+	} A, B, C, D;
+	
+	detail::uint32 Mask8((1 << 8) - 1);
+	A.u = detail::uint8((p >>  0) & Mask8);
+	B.u = detail::uint8((p >>  8) & Mask8);
+	C.u = detail::uint8((p >> 16) & Mask8);
+	D.u = detail::uint8((p >> 24) & Mask8);
+	vec4 Pack(A.i, B.i, C.i, D.i);
+	
+	return clamp(Pack, -1.0f, 1.0f);
 }
 
 GLM_FUNC_QUALIFIER double packDouble2x32(detail::tvec2<detail::uint32> const & v)

test/core/core_func_packing.cpp

@@ -55,6 +55,46 @@ int test_packSnorm2x16()
 	return Error;
 }
 
+int test_packUnorm4x8()
+{
+	int Error = 0;
+	
+	std::vector<glm::vec4> A;
+	A.push_back(glm::vec4(1.0f, 0.7f, 0.3f, 0.0f));
+	A.push_back(glm::vec4(0.5f, 0.1f, 0.2f, 0.3f));
+	
+	for(std::size_t i = 0; i < A.size(); ++i)
+	{
+		glm::vec4 B(A[i]);
+		glm::uint32 C = glm::packUnorm4x8(B);
+		glm::vec4 D = glm::unpackUnorm4x8(C);
+		Error += glm::all(glm::equalEpsilon(B, D, 0.0001f)) ? 0 : 1;
+		assert(!Error);
+	}
+	
+	return Error;
+}
+
+int test_packSnorm4x8()
+{
+	int Error = 0;
+	
+	std::vector<glm::vec4> A;
+	A.push_back(glm::vec4( 1.0f, 0.0f,-0.5f,-1.0f));
+	A.push_back(glm::vec4(-0.7f,-0.1f, 0.1f, 0.7f));
+	
+	for(std::size_t i = 0; i < A.size(); ++i)
+	{
+		glm::vec4 B(A[i]);
+		glm::uint32 C = glm::packSnorm4x8(B);
+		glm::vec4 D = glm::unpackSnorm4x8(C);
+		Error += glm::all(glm::equalEpsilon(B, D, 0.0001f)) ? 0 : 1;
+		//assert(!Error);
+	}
+	
+	return Error;
+}
+
 int test_packHalf2x16()
 {
 	int Error = 0;
@@ -99,11 +139,13 @@ int main()
 {
 	int Error = 0;
 	
+	Error += test_packSnorm4x8();
+	Error += test_packUnorm4x8();
 	Error += test_packSnorm2x16();
 	Error += test_packUnorm2x16();
 	Error += test_packHalf2x16();
 	Error += test_packDouble2x32();
-	
+
 	return Error;
 }