Change msdf.hlsl function to get precomputed pixel range instead

Author: Erfan-Ahmadi

include/nbl/builtin/hlsl/text_rendering/msdf.hlsl

@@ -23,19 +23,18 @@ This can then be processed using smoothstep to provide anti-alising when renderi
 @params:
 - msdfSample: sampled SNORM value from the MSDF texture generated by msdfgen library.
 
-- msdfPixelRange: specifies the width of the range around the shape between the minimum and maximum representable signed distance in shape units or distance field pixels, respectivelly.
-  for example if msdfPixelRange is 4, then the range of distance values are [-2, +2], and it can be computed by snormValue * MSDFPixelRange/2.0
-    so an snorm value of 1.0 means a distance of 2 pixels outside the shape (in msdf texture space)
-    This value is set when rendering the MSDF with MSDFgen.
-
-- screenPxRangeValue: the value used to convert the distance values in the msdf texture/atlas to distance in screen space. 
-  In other words it's DistanceInScreenSpace/DistanceInMSDFTextureSpace, the larger the glyph (or more zoomed in) the larger this value is.
-  In 2D Text Rendering it is computed by `GlyphScreenSpaceSize/GlyphTextureSpaceSize`
-  where GlyphTextureSpaceSize is the size of the glyph inside the msdf texture/atlas
+- pixelRange = msdfPixelRange * screenPxRangeValue, It is the value to convert snorm distance to screen space distance
+    - msdfPixelRange: specifies the width of the range around the shape between the minimum and maximum representable signed distance in shape units or distance field pixels, respectivelly.
+        for example if msdfPixelRange is 4, then the range of distance values are [-2, +2], and it can be computed by snormValue * MSDFPixelRange/2.0
+        so an snorm value of 1.0 means a distance of 2 pixels outside the shape (in msdf texture space)
+        This value is set when rendering the MSDF with MSDFgen.
+    - screenPxRangeValue: the value used to convert the distance values in the msdf texture/atlas to distance in screen space. 
+        In other words it's DistanceInScreenSpace/DistanceInMSDFTextureSpace, the larger the glyph (or more zoomed in) the larger this value is.
+        In 2D Text Rendering it is computed by `GlyphScreenSpaceSize/GlyphTextureSpaceSize`
+         where GlyphTextureSpaceSize is the size of the glyph inside the msdf texture/atlas
 */
-float msdfDistance(float3 msdfSample, float msdfPixelRange, float screenPxRangeValue) {
-    float texelDist = median(msdfSample.r, msdfSample.g, msdfSample.b) * msdfPixelRange / 2.0f;
-    return texelDist * screenPxRangeValue;
+float msdfDistance(float3 msdfSample, float pixelRange) {
+    return median(msdfSample.r, msdfSample.g, msdfSample.b) * pixelRange / 2.0f;
 }
 
 }