FGFS-4.1/OpenSceneGraph
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Umproved SDF computation.

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This commit is contained in:
Robert Osfield
2017-09-21 14:32:17 +01:00
parent e565a5e1c3
commit e72a38c8b6
1 changed files with 80 additions and 41 deletions
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121
src/osgText/Glyph.cpp
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@@ -175,6 +175,11 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
if ((upper+glyph->getTexturePositionY())>=dest_rows) upper = dest_rows-glyph->getTexturePositionY()-1;
bool use_SDF_for_Outline = true;
float outer_outline_distance = float(search_distance);
float inner_outline_distance = float(outer_outline_distance)/2.0f;
for(int dr=lower; dr<=upper; ++dr)
{
for(int dc=left; dc<=right; ++dc)
@@ -184,11 +189,17 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
unsigned char center_value = 0;
if (dr>=0 && dr<src_rows && dc>=0 && dc<src_columns) center_value = *(src_data + dr*src_columns + dc);
unsigned char inner_max_value = center_value;
unsigned char outer_max_value = center_value;
float center_value_f = center_value*multiplier;
float min_distance = FLT_MAX;
if (center_value>0 && center_value<255)
{
inner_max_value = 255;
outer_max_value = 255;
if (center_value_f>=0.5f)
{
min_distance = center_value_f-0.5f;
@@ -204,7 +215,7 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
{
for(int radius=1; radius<search_distance; ++radius)
{
for(int span=-radius; span<radius; ++span)
for(int span=-radius; span<=radius; ++span)
{
{
// left
@@ -228,11 +239,42 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
else local_distance += (local_value_f - 0.5f)*local_multiplier;
if (local_distance<min_distance) min_distance = local_distance;
if (local_value>inner_max_value && local_distance<=inner_outline_distance) inner_max_value = local_value;
if (local_value>outer_max_value && local_distance<=outer_outline_distance) outer_max_value = local_value;
}
}
{
// top
int dx = span;
int dy = radius;
int c = dc+dx;
int r = dr+dy;
unsigned char local_value = 0;
if (r>=0 && r<src_rows && c>=0 && c<src_columns) local_value = *(src_data + r*src_columns + c);
if (local_value!=center_value)
{
float local_value_f = float(local_value)*multiplier;
float D = sqrtf(float(dx*dx) + float(dy*dy));
float local_multiplier = (abs(dx)>abs(dy)) ? D/float(abs(dx)) : D/float(abs(dy));
float local_distance = sqrtf(float(radius*radius)+float(span*span));
if (center_value==0) local_distance += (0.5f-local_value_f)*local_multiplier;
else local_distance += (local_value_f - 0.5f)*local_multiplier;
if (local_distance<min_distance) min_distance = local_distance;
if (local_value>inner_max_value && local_distance<=inner_outline_distance) inner_max_value = local_value;
if (local_value>outer_max_value && local_distance<=outer_outline_distance) outer_max_value = local_value;
}
}
{
// right
int dx = radius;
int dy = span;
@@ -249,42 +291,21 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
float local_multiplier = (abs(dx)>abs(dy)) ? D/float(abs(dx)) : D/float(abs(dy));
float local_distance = sqrtf(float(radius*radius)+float(span*span));
if (center_value==0) local_distance += (0.5f-local_value_f)*local_multiplier;
else local_distance += (local_value_f - 0.5f)*local_multiplier;
if (local_distance<min_distance) min_distance = local_distance;
}
}
{
// right
int dx = radius;
int dy = -span;
int c = dc+dx;
int r = dr+dy;
unsigned char local_value = 0;
if (r>=0 && r<src_rows && c>=0 && c<src_columns) local_value = *(src_data + r*src_columns + c);
if (local_value!=center_value)
{
float local_value_f = float(local_value)*multiplier;
float D = sqrtf(float(dx*dx) + float(dy*dy));
float local_multiplier = (abs(dx)>abs(dy)) ? D/float(abs(dx)) : D/float(abs(dy));
float local_distance = sqrtf(float(radius*radius)+float(span*span));
if (center_value==0) local_distance += (0.5f-local_value_f)*local_multiplier;
else local_distance += (local_value_f - 0.5f)*local_multiplier;
if (local_distance<min_distance) min_distance = local_distance;
if (local_value>inner_max_value && local_distance<=inner_outline_distance) inner_max_value = local_value;
if (local_value>outer_max_value && local_distance<=outer_outline_distance) outer_max_value = local_value;
}
}
{
// bottom
int dx = -radius;
int dy = -span;
int dx = span;
int dy = -radius;
int c = dc+dx;
int r = dr+dy;
@@ -303,6 +324,9 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
else local_distance += (local_value_f - 0.5f)*local_multiplier;
if (local_distance<min_distance) min_distance = local_distance;
if (local_value>inner_max_value && local_distance<=inner_outline_distance) inner_max_value = local_value;
if (local_value>outer_max_value && local_distance<=outer_outline_distance) outer_max_value = local_value;
}
}
}
@@ -329,16 +353,24 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
// compute the alpha value of outline, one texel thick
unsigned char outline = 0;
if (center_value<255)
if (use_SDF_for_Outline)
{
float inner_outline = outline_distance-1.0f;
if (min_distance<inner_outline) outline = 255;
else if (min_distance<=outline_distance) outline = (unsigned char)(255.0*(outline_distance-min_distance)/(outline_distance-inner_outline));
else outline = 0;
if (center_value<255)
{
float inner_outline = outline_distance-1.0f;
if (min_distance<inner_outline) outline = 255;
else if (min_distance<=outline_distance) outline = (unsigned char)(255.0*(outline_distance-min_distance)/(outline_distance-inner_outline));
else outline = 0;
}
if (outline>center_value)
{
outline -= center_value;
}
}
if (outline>center_value)
else
{
outline -= center_value;
outline = inner_max_value-center_value;
}
*(dest_ptr++) = outline;
@@ -348,16 +380,23 @@ void GlyphTexture::copyGlyphImage(Glyph* glyph)
// compute the alpha value of outline, one texel thick
outline = 0;
if (center_value<255)
if (use_SDF_for_Outline)
{
float inner_outline = outline_distance-1.0f;
if (min_distance<inner_outline) outline = 255;
else if (min_distance<=outline_distance) outline = (unsigned char)(255.0*(outline_distance-min_distance)/(outline_distance-inner_outline));
else outline = 0;
if (center_value<255)
{
float inner_outline = outline_distance-1.0f;
if (min_distance<inner_outline) outline = 255;
else if (min_distance<=outline_distance) outline = (unsigned char)(255.0*(outline_distance-min_distance)/(outline_distance-inner_outline));
else outline = 0;
}
if (outline>center_value)
{
outline -= center_value;
}
}
if (outline>center_value)
else
{
outline -= center_value;
outline = outer_max_value-center_value;
}
*(dest_ptr++) = outline;