wip: rewrite unpackUnorm4x8 with explicit typing

Author: illwieckz

src/engine/renderer/gl_shader.cpp

@@ -529,10 +529,6 @@ static std::string GenCompatHeader() {
 		str += "float smoothstep(float edge0, float edge1, float x) { float t = clamp((x - edge0) / (edge1 - edge0), 0.0, 1.0); return t * t * (3.0 - 2.0 * t); }\n";
 	}
 
-	if ( !glConfig2.gpuShader5Available ) {
-		str += "#define unpackUnorm4x8( value ) ( ( vec4( value, value >> 8, value >> 16, value >> 24 ) & 0xFF ) / 255.0f )\n";
-	}
-
 	/* Driver bug: Adrenaline/OGLP drivers fail to recognise the ARB function versions when they return a 4.6 context
 	and the shaders get #version 460 core, so add #define's for them here */
 	if ( glConfig2.driverVendor == glDriverVendor_t::ATI && glConfig2.shaderAtomicCounterOpsAvailable ) {

src/engine/renderer/glsl_source/common.glsl

@@ -45,6 +45,18 @@ array must be in the form of uvec4 array[] */
 
 // Common functions
 
+#if !defined(HAVE_ARB_gpu_shader5) && defined(HAVE_EXT_gpu_shader4)
+vec4 unpackUnorm4x8( uint value )
+{
+	uint x = value & 255u;
+	uint y = ( value >> 8u ) & 255u;
+	uint z = ( value >> 16u ) & 255u;
+	uint w = ( value >> 24u ) & 255u;
+
+	return vec4( x, y, z, w ) / 255.0f;
+}
+#endif
+
 #if defined(HAVE_EXT_gpu_shader4)
 	#define colorPack uint
 	#define colorModulatePack uint