Fixed RGB19E7 encode in GLSL

Author: Crisspl

include/nbl/builtin/glsl/format/encode.glsl

@@ -8,14 +8,19 @@ uvec2 nbl_glsl_encodeRGB19E7(in vec3 col)
 	const vec3 clamped = clamp(col,vec3(0.0),vec3(nbl_glsl_MAX_RGB19E7));
 	const float maxrgb = max(max(clamped.r,clamped.g),clamped.b);
 
-	const int f32_exp = bitfieldExtract(floatBitsToInt(maxrgb),23,8)-127;
-	const int shared_exp = clamp(f32_exp,-nbl_glsl_RGB19E7_EXP_BIAS,nbl_glsl_MAX_RGB19E7_EXP);
+	const int f32_exp = ((floatBitsToInt(maxrgb)>>23) & 0xff) - 127;
+	const int shared_exp = clamp(f32_exp,-nbl_glsl_RGB19E7_EXP_BIAS-1,nbl_glsl_MAX_RGB19E7_EXP) + 1;
 
-	const uvec3 mantissas = uvec3(clamped*exp2(nbl_glsl_RGB19E7_MANTISSA_BITS-shared_exp));
+	const uvec3 mantissas = uvec3(clamped*exp2(nbl_glsl_RGB19E7_MANTISSA_BITS-shared_exp) + 0.5);
 
 	uvec2 encoded;
 	encoded.x = bitfieldInsert(mantissas.x,mantissas.y,nbl_glsl_RGB19E7_COMPONENT_BITOFFSETS[1],nbl_glsl_RGB19E7_G_COMPONENT_SPLIT);
-	encoded.y = bitfieldInsert(mantissas.y>>nbl_glsl_RGB19E7_G_COMPONENT_SPLIT,mantissas.z,nbl_glsl_RGB19E7_COMPONENT_BITOFFSETS[2],nbl_glsl_RGB19E7_MANTISSA_BITS)|uint((shared_exp+nbl_glsl_RGB19E7_EXP_BIAS)<<nbl_glsl_RGB19E7_COMPONENT_BITOFFSETS[3]);
+	encoded.y = bitfieldInsert(
+		mantissas.y>>nbl_glsl_RGB19E7_G_COMPONENT_SPLIT,
+		mantissas.z,
+		nbl_glsl_RGB19E7_COMPONENT_BITOFFSETS[2],
+		nbl_glsl_RGB19E7_MANTISSA_BITS)
+	| uint((shared_exp+nbl_glsl_RGB19E7_EXP_BIAS)<<nbl_glsl_RGB19E7_COMPONENT_BITOFFSETS[3]);
 
 	return encoded;
 }