Origin pixel alignment per axis, CLI setting

README.md

@@ -109,6 +109,7 @@ Any non-empty subset of the following may be specified:
 - `-minsize <EM size>` &ndash; sets the minimum size. The largest possible size that fits the same atlas dimensions will be used
 - `-emrange <EM range>` &ndash; sets the distance field range in EM's
 - `-pxrange <pixel range>` (default = 2) &ndash; sets the distance field range in output pixels
+- `-pxalign <on / off / horizontal / vertical>` (default = vertical) &ndash; enables or disables alignment of glyph's origin point with the pixel grid
 
 ### Distance field generator settings
 

msdf-atlas-gen/GlyphGeometry.cpp

@@ -51,32 +51,11 @@ void GlyphGeometry::edgeColoring(void (*fn)(msdfgen::Shape &, double, unsigned l
     fn(shape, angleThreshold, seed);
 }
 
-void GlyphGeometry::wrapBox(double scale, double range, double miterLimit) {
+void GlyphGeometry::wrapBox(double scale, double range, double miterLimit, bool alignOrigin) {
-    scale *= geometryScale;
+    wrapBox(scale, range, miterLimit, alignOrigin, alignOrigin);
-    range /= geometryScale;
-    box.range = range;
-    box.scale = scale;
-    if (bounds.l < bounds.r && bounds.b < bounds.t) {
-        double l = bounds.l, b = bounds.b, r = bounds.r, t = bounds.t;
-        l -= .5*range, b -= .5*range;
-        r += .5*range, t += .5*range;
-        if (miterLimit > 0)
-            shape.boundMiters(l, b, r, t, .5*range, miterLimit, 1);
-        int sl = (int) floor(scale*l-.5);
-        int sb = (int) floor(scale*b-.5);
-        int sr = (int) ceil(scale*r+.5);
-        int st = (int) ceil(scale*t+.5);
-        box.rect.w = sr-sl;
-        box.rect.h = st-sb;
-        box.translate.x = -sl/scale;
-        box.translate.y = -sb/scale;
-    } else {
-        box.rect.w = 0, box.rect.h = 0;
-        box.translate = msdfgen::Vector2();
-    }
 }
 
-void GlyphGeometry::wrapBoxUnaligned(double scale, double range, double miterLimit) {
+void GlyphGeometry::wrapBox(double scale, double range, double miterLimit, bool alignOriginX, bool alignOriginY) {
     scale *= geometryScale;
     range /= geometryScale;
     box.range = range;
@@ -87,12 +66,26 @@ void GlyphGeometry::wrapBoxUnaligned(double scale, double range, double miterLim
         r += .5*range, t += .5*range;
         if (miterLimit > 0)
             shape.boundMiters(l, b, r, t, .5*range, miterLimit, 1);
+        if (alignOriginX) {
+            int sl = (int) floor(scale*l-.5);
+            int sr = (int) ceil(scale*r+.5);
+            box.rect.w = sr-sl;
+            box.translate.x = -sl/scale;
+        } else {
             double w = scale*(r-l);
-        double h = scale*(t-b);
             box.rect.w = (int) ceil(w)+1;
-        box.rect.h = (int) ceil(h)+1;
             box.translate.x = -l+.5*(box.rect.w-w)/scale;
+        }
+        if (alignOriginY) {
+            int sb = (int) floor(scale*b-.5);
+            int st = (int) ceil(scale*t+.5);
+            box.rect.h = st-sb;
+            box.translate.y = -sb/scale;
+        } else {
+            double h = scale*(t-b);
+            box.rect.h = (int) ceil(h)+1;
             box.translate.y = -b+.5*(box.rect.h-h)/scale;
+        }
     } else {
         box.rect.w = 0, box.rect.h = 0;
         box.translate = msdfgen::Vector2();

msdf-atlas-gen/GlyphGeometry.h

@@ -20,9 +20,8 @@ public:
     /// Applies edge coloring to glyph shape
     void edgeColoring(void (*fn)(msdfgen::Shape &, double, unsigned long long), double angleThreshold, unsigned long long seed);
     /// Computes the dimensions of the glyph's box as well as the transformation for the generator function
-    void wrapBox(double scale, double range, double miterLimit);
+    void wrapBox(double scale, double range, double miterLimit, bool alignOrigin = false);
-    /// Computes the dimensions of the glyph's box and the transformation for the generator function, allowing origin to be located at a non-integer coordinate
+    void wrapBox(double scale, double range, double miterLimit, bool alignOriginX, bool alignOriginY);
-    void wrapBoxUnaligned(double scale, double range, double miterLimit);
     /// Sets the glyph's box's position in the atlas
     void placeBox(int x, int y);
     /// Sets the glyph's box's rectangle in the atlas

msdf-atlas-gen/TightAtlasPacker.cpp

@@ -17,6 +17,7 @@ TightAtlasPacker::TightAtlasPacker() :
     unitRange(0),
     pxRange(0),
     miterLimit(0),
+    alignOriginX(false), alignOriginY(false),
     scaleMaximizationTolerance(.001)
 { }
 
@@ -30,7 +31,7 @@ int TightAtlasPacker::tryPack(GlyphGeometry *glyphs, int count, DimensionsConstr
     for (GlyphGeometry *glyph = glyphs, *end = glyphs+count; glyph < end; ++glyph) {
         if (!glyph->isWhitespace()) {
             Rectangle rect = { };
-            glyph->wrapBox(scale, range, miterLimit);
+            glyph->wrapBox(scale, range, miterLimit, alignOriginX, alignOriginY);
             glyph->getBoxSize(rect.w, rect.h);
             if (rect.w > 0 && rect.h > 0) {
                 rectangles.push_back(rect);
@@ -155,6 +156,14 @@ void TightAtlasPacker::setMiterLimit(double miterLimit) {
     this->miterLimit = miterLimit;
 }
 
+void TightAtlasPacker::setOriginAlignment(bool align) {
+    alignOriginX = align, alignOriginY = align;
+}
+
+void TightAtlasPacker::setOriginAlignment(bool alignX, bool alignY) {
+    alignOriginX = alignX, alignOriginY = alignY;
+}
+
 void TightAtlasPacker::getDimensions(int &width, int &height) const {
     width = this->width, height = this->height;
 }

msdf-atlas-gen/TightAtlasPacker.h

@@ -44,6 +44,9 @@ public:
     void setPixelRange(double pxRange);
     /// Sets the miter limit for bounds computation
     void setMiterLimit(double miterLimit);
+    /// Sets whether each glyph's origin point should stay aligned with the pixel grid
+    void setOriginAlignment(bool align);
+    void setOriginAlignment(bool alignX, bool alignY);
 
     /// Outputs the atlas's final dimensions
     void getDimensions(int &width, int &height) const;
@@ -61,6 +64,7 @@ private:
     double unitRange;
     double pxRange;
     double miterLimit;
+    bool alignOriginX, alignOriginY;
     double scaleMaximizationTolerance;
 
     int tryPack(GlyphGeometry *glyphs, int count, DimensionsConstraint dimensionsConstraint, int &width, int &height, double scale) const;

msdf-atlas-gen/main.cpp

@@ -111,6 +111,8 @@ GLYPH CONFIGURATION
       Specifies the SDF distance range in EM's.
   -pxrange <pixel range>
       Specifies the SDF distance range in output pixels. The default value is 2.
+  -pxalign <on / off / horizontal / vertical>
+      Specifies whether each glyph's origin point should be aligned with the pixel grid.
   -nokerning
       Disables inclusion of kerning pair table in output files.
 
@@ -250,6 +252,7 @@ struct Configuration {
     double pxRange;
     double angleThreshold;
     double miterLimit;
+    bool alignOriginX, alignOriginY;
     void (*edgeColoring)(msdfgen::Shape &, double, unsigned long long);
     bool expensiveColoring;
     unsigned long long coloringSeed;
@@ -340,6 +343,7 @@ int main(int argc, const char * const *argv) {
     TightAtlasPacker::DimensionsConstraint atlasSizeConstraint = TightAtlasPacker::DimensionsConstraint::MULTIPLE_OF_FOUR_SQUARE;
     config.angleThreshold = DEFAULT_ANGLE_THRESHOLD;
     config.miterLimit = DEFAULT_MITER_LIMIT;
+    config.alignOriginX = false, config.alignOriginY = true;
     config.threadCount = 0;
 
     // Parse command line
@@ -561,6 +565,20 @@ int main(int argc, const char * const *argv) {
             ++argPos;
             continue;
         }
+        ARG_CASE("-pxalign", 1) {
+            if (!strcmp(argv[argPos+1], "off") || !memcmp(argv[argPos+1], "disable", 7) || !strcmp(argv[argPos+1], "0") || argv[argPos+1][0] == 'n')
+                config.alignOriginX = false, config.alignOriginY = false;
+            else if (!strcmp(argv[argPos+1], "on") || !memcmp(argv[argPos+1], "enable", 6) || !strcmp(argv[argPos+1], "1") || argv[argPos+1][0] == 'y')
+                config.alignOriginX = true, config.alignOriginY = true;
+            else if (argv[argPos+1][0] == 'h')
+                config.alignOriginX = true, config.alignOriginY = false;
+            else if (argv[argPos+1][0] == 'v' || !strcmp(argv[argPos+1], "baseline") || !strcmp(argv[argPos+1], "default"))
+                config.alignOriginX = false, config.alignOriginY = true;
+            else
+                ABORT("Unknown -pxalign setting. Use on, off, horizontal, or vertical.");
+            argPos += 2;
+            continue;
+        }
         ARG_CASE("-angle", 1) {
             double at;
             if (!parseAngle(at, argv[argPos+1]))
@@ -571,7 +589,7 @@ int main(int argc, const char * const *argv) {
         }
         ARG_CASE("-errorcorrection", 1) {
             msdfgen::ErrorCorrectionConfig &ec = config.generatorAttributes.config.errorCorrection;
-            if (!strcmp(argv[argPos+1], "disabled") || !strcmp(argv[argPos+1], "0") || !strcmp(argv[argPos+1], "none")) {
+            if (!memcmp(argv[argPos+1], "disable", 7) || !strcmp(argv[argPos+1], "0") || !strcmp(argv[argPos+1], "none")) {
                 ec.mode = msdfgen::ErrorCorrectionConfig::DISABLED;
                 ec.distanceCheckMode = msdfgen::ErrorCorrectionConfig::DO_NOT_CHECK_DISTANCE;
             } else if (!strcmp(argv[argPos+1], "default") || !strcmp(argv[argPos+1], "auto") || !strcmp(argv[argPos+1], "auto-mixed") || !strcmp(argv[argPos+1], "mixed")) {
@@ -714,7 +732,8 @@ int main(int argc, const char * const *argv) {
                 ".exe"
             #endif
             " -font <filename.ttf/otf> -charset <charset> <output specification> <options>\n"
-            "Use -help for more information.\n", stderr
+            "Use -help for more information.\n",
+            stderr
         );
         return 0;
     }
@@ -789,8 +808,12 @@ int main(int argc, const char * const *argv) {
         config.imageFormat = ImageFormat::PNG;
         imageFormatName = "png";
         // If image format is not specified and -imageout is the only image output, infer format from its extension
-        if (imageExtension != ImageFormat::UNSPECIFIED && !config.arteryFontFilename)
+        if (!config.arteryFontFilename) {
+            if (imageExtension != ImageFormat::UNSPECIFIED)
                 config.imageFormat = imageExtension;
+            else
+                fputs("Warning: Could not infer image format from file extension, PNG will be used.\n", stderr);
+        }
     }
     if (config.imageType == ImageType::MTSDF && config.imageFormat == ImageFormat::BMP)
         ABORT("Atlas type not compatible with image format. MTSDF requires a format with alpha channel.");
@@ -966,6 +989,7 @@ int main(int argc, const char * const *argv) {
         atlasPacker.setPixelRange(pxRange);
         atlasPacker.setUnitRange(unitRange);
         atlasPacker.setMiterLimit(config.miterLimit);
+        atlasPacker.setOriginAlignment(config.alignOriginX, config.alignOriginY);
         if (int remaining = atlasPacker.pack(glyphs.data(), glyphs.size())) {
             if (remaining < 0) {
                 ABORT("Failed to pack glyphs into atlas.");