Last active
May 26, 2024 19:21
-
-
Save Flix01/254005101903fe1bc22fe0b9f3ed3931 to your computer and use it in GitHub Desktop.
A Signed Distance Font Builder for Dear ImGui
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| /* | |
| * edtaa3() | |
| * | |
| * Sweep-and-update Euclidean distance transform of an | |
| * image. Positive pixels are treated as object pixels, | |
| * zero or negative pixels are treated as background. | |
| * An attempt is made to treat antialiased edges correctly. | |
| * The input image must have pixels in the range [0,1], | |
| * and the antialiased image should be a box-filter | |
| * sampling of the ideal, crisp edge. | |
| * If the antialias region is more than 1 pixel wide, | |
| * the result from this transform will be inaccurate. | |
| * | |
| * By Stefan Gustavson ([email protected]). | |
| * | |
| * Originally written in 1994, based on a verbal | |
| * description of the SSED8 algorithm published in the | |
| * PhD dissertation of Ingemar Ragnemalm. This is his | |
| * algorithm, I only implemented it in C. | |
| * | |
| * Updated in 2004 to treat border pixels correctly, | |
| * and cleaned up the code to improve readability. | |
| * | |
| * Updated in 2009 to handle anti-aliased edges. | |
| * | |
| * Updated in 2011 to avoid a corner case infinite loop. | |
| * | |
| * Updated 2012 to change license from LGPL to MIT. | |
| * | |
| * Updated 2014 to fix a bug in the gradient computations. Ahem. | |
| * | |
| */ | |
| /* | |
| Copyright (C) 2009-2012 Stefan Gustavson ([email protected]) | |
| The code in this file is distributed under the MIT license: | |
| Permission is hereby granted, free of charge, to any person obtaining a copy | |
| of this software and associated documentation files (the "Software"), to deal | |
| in the Software without restriction, including without limitation the rights | |
| to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| copies of the Software, and to permit persons to whom the Software is | |
| furnished to do so, subject to the following conditions: | |
| The above copyright notice and this permission notice shall be included in | |
| all copies or substantial portions of the Software. | |
| THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
| OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
| THE SOFTWARE. | |
| */ | |
| // Flix01: Added the EDTAA3FUNC_HAS_IMGUI_SUPPORT definition that can be used | |
| // to provide Dear Imgui (at https://github.com/ocornut/imgui) the method: | |
| // ImGui::PostBuildForSignedDistanceFontEffect(ImFontAtlas* atlas). | |
| // USAGE: | |
| /* | |
| // In imgui_impl_glfw.cpp (or similiar): | |
| #define IMIMPL_BUILD_SDF // Twickable | |
| #ifdef IMIMPL_BUILD_SDF | |
| #define EDTAA3FUNC_HAS_IMGUI_SUPPORT | |
| #include "edtaa3func.h" | |
| #endif //IMIMPL_BUILD_SDF | |
| bool ImGui_ImplGlfw_CreateFontsTexture() | |
| { | |
| // Build texture atlas | |
| ImGuiIO& io = ImGui::GetIO(); | |
| unsigned char* pixels; | |
| int width, height; | |
| // New code ------------------------------------------------- | |
| if (io.Fonts->ConfigData.empty()) io.Fonts->AddFontDefault(); | |
| io.Fonts->Build(); // (change this line if you use [imgui_freetype](https://github.com/Vuhdo/imgui) appropriately) | |
| # ifdef IMIMPL_BUILD_SDF | |
| ImGui::PostBuildForSignedDistanceFontEffect(io.Fonts); | |
| # endif //IMIMPL_BUILD_SDF | |
| // End new code ---------------------------------------------- | |
| ... | |
| } | |
| */ | |
| // The methods ImGuiEdtaaHelper::make_distance_mapd(...) and ImGuiEdtaaHelper::make_distance_mapb(...) | |
| // are based on https://github.com/rougier/freetype-gl/blob/master/distance-field.c [Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.] | |
| // freetype-gl license: | |
| /* | |
| /* ========================================================================= | |
| * Freetype GL - A C OpenGL Freetype engine | |
| * Platform: Any | |
| * WWW: https://github.com/rougier/freetype-gl | |
| * ------------------------------------------------------------------------- | |
| * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved. | |
| * | |
| * Redistribution and use in source and binary forms, with or without | |
| * modification, are permitted provided that the following conditions are met: | |
| * | |
| * 1. Redistributions of source code must retain the above copyright notice, | |
| * this list of conditions and the following disclaimer. | |
| * | |
| * 2. Redistributions in binary form must reproduce the above copyright | |
| * notice, this list of conditions and the following disclaimer in the | |
| * documentation and/or other materials provided with the distribution. | |
| * | |
| * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''AS IS'' AND ANY EXPRESS OR | |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF | |
| * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO | |
| * EVENT SHALL NICOLAS P. ROUGIER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, | |
| * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND | |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| * | |
| * The views and conclusions contained in the software and documentation are | |
| * those of the authors and should not be interpreted as representing official | |
| * policies, either expressed or implied, of Nicolas P. Rougier. | |
| * ========================================================================= | |
| */ | |
| #ifndef EDTAA3FUNC_H_ | |
| #define EDTAA3FUNC_H_ | |
| #pragma once | |
| #include <math.h> | |
| #ifdef __cplusplus | |
| extern "C" { | |
| #endif //__cplusplus | |
| /* | |
| * Compute the local gradient at edge pixels using convolution filters. | |
| * The gradient is computed only at edge pixels. At other places in the | |
| * image, it is never used, and it's mostly zero anyway. | |
| */ | |
| void computegradient(double *img, int w, int h, double *gx, double *gy) | |
| { | |
| int i,j,k,p,q; | |
| double glength, phi, phiscaled, ascaled, errsign, pfrac, qfrac, err0, err1, err; | |
| #define SQRT2 1.4142136 | |
| for(i = 1; i < h-1; i++) { // Avoid edges where the kernels would spill over | |
| for(j = 1; j < w-1; j++) { | |
| k = i*w + j; | |
| if((img[k]>0.0) && (img[k]<1.0)) { // Compute gradient for edge pixels only | |
| gx[k] = -img[k-w-1] - SQRT2*img[k-1] - img[k+w-1] + img[k-w+1] + SQRT2*img[k+1] + img[k+w+1]; | |
| gy[k] = -img[k-w-1] - SQRT2*img[k-w] - img[k-w+1] + img[k+w-1] + SQRT2*img[k+w] + img[k+w+1]; | |
| glength = gx[k]*gx[k] + gy[k]*gy[k]; | |
| if(glength > 0.0) { // Avoid division by zero | |
| glength = sqrt(glength); | |
| gx[k]=gx[k]/glength; | |
| gy[k]=gy[k]/glength; | |
| } | |
| } | |
| } | |
| } | |
| // TODO: Compute reasonable values for gx, gy also around the image edges. | |
| // (These are zero now, which reduces the accuracy for a 1-pixel wide region | |
| // around the image edge.) 2x2 kernels would be suitable for this. | |
| } | |
| /* | |
| * A somewhat tricky function to approximate the distance to an edge in a | |
| * certain pixel, with consideration to either the local gradient (gx,gy) | |
| * or the direction to the pixel (dx,dy) and the pixel greyscale value a. | |
| * The latter alternative, using (dx,dy), is the metric used by edtaa2(). | |
| * Using a local estimate of the edge gradient (gx,gy) yields much better | |
| * accuracy at and near edges, and reduces the error even at distant pixels | |
| * provided that the gradient direction is accurately estimated. | |
| */ | |
| double edgedf(double gx, double gy, double a) | |
| { | |
| double df, glength, temp, a1; | |
| if ((gx == 0) || (gy == 0)) { // Either A) gu or gv are zero, or B) both | |
| df = 0.5-a; // Linear approximation is A) correct or B) a fair guess | |
| } else { | |
| glength = sqrt(gx*gx + gy*gy); | |
| if(glength>0) { | |
| gx = gx/glength; | |
| gy = gy/glength; | |
| } | |
| /* Everything is symmetric wrt sign and transposition, | |
| * so move to first octant (gx>=0, gy>=0, gx>=gy) to | |
| * avoid handling all possible edge directions. | |
| */ | |
| gx = fabs(gx); | |
| gy = fabs(gy); | |
| if(gx<gy) { | |
| temp = gx; | |
| gx = gy; | |
| gy = temp; | |
| } | |
| a1 = 0.5*gy/gx; | |
| if (a < a1) { // 0 <= a < a1 | |
| df = 0.5*(gx + gy) - sqrt(2.0*gx*gy*a); | |
| } else if (a < (1.0-a1)) { // a1 <= a <= 1-a1 | |
| df = (0.5-a)*gx; | |
| } else { // 1-a1 < a <= 1 | |
| df = -0.5*(gx + gy) + sqrt(2.0*gx*gy*(1.0-a)); | |
| } | |
| } | |
| return df; | |
| } | |
| double distaa3(double *img, double *gximg, double *gyimg, int w, int c, int xc, int yc, int xi, int yi) | |
| { | |
| double di, df, dx, dy, gx, gy, a; | |
| int closest; | |
| closest = c-xc-yc*w; // Index to the edge pixel pointed to from c | |
| a = img[closest]; // Grayscale value at the edge pixel | |
| gx = gximg[closest]; // X gradient component at the edge pixel | |
| gy = gyimg[closest]; // Y gradient component at the edge pixel | |
| if(a > 1.0) a = 1.0; | |
| if(a < 0.0) a = 0.0; // Clip grayscale values outside the range [0,1] | |
| if(a == 0.0) return 1000000.0; // Not an object pixel, return "very far" ("don't know yet") | |
| dx = (double)xi; | |
| dy = (double)yi; | |
| di = sqrt(dx*dx + dy*dy); // Length of integer vector, like a traditional EDT | |
| if(di==0) { // Use local gradient only at edges | |
| // Estimate based on local gradient only | |
| df = edgedf(gx, gy, a); | |
| } else { | |
| // Estimate gradient based on direction to edge (accurate for large di) | |
| df = edgedf(dx, dy, a); | |
| } | |
| return di + df; // Same metric as edtaa2, except at edges (where di=0) | |
| } | |
| // Shorthand macro: add ubiquitous parameters dist, gx, gy, img and w and call distaa3() | |
| #define DISTAA(c,xc,yc,xi,yi) (distaa3(img, gx, gy, w, c, xc, yc, xi, yi)) | |
| void edtaa3(double *img, double *gx, double *gy, int w, int h, short *distx, short *disty, double *dist) | |
| { | |
| int x, y, i, c; | |
| int offset_u, offset_ur, offset_r, offset_rd, | |
| offset_d, offset_dl, offset_l, offset_lu; | |
| double olddist, newdist; | |
| int cdistx, cdisty, newdistx, newdisty; | |
| int changed; | |
| double epsilon = 1e-3; | |
| /* Initialize index offsets for the current image width */ | |
| offset_u = -w; | |
| offset_ur = -w+1; | |
| offset_r = 1; | |
| offset_rd = w+1; | |
| offset_d = w; | |
| offset_dl = w-1; | |
| offset_l = -1; | |
| offset_lu = -w-1; | |
| /* Initialize the distance images */ | |
| for(i=0; i<w*h; i++) { | |
| distx[i] = 0; // At first, all pixels point to | |
| disty[i] = 0; // themselves as the closest known. | |
| if(img[i] <= 0.0) | |
| { | |
| dist[i]= 1000000.0; // Big value, means "not set yet" | |
| } | |
| else if (img[i]<1.0) { | |
| dist[i] = edgedf(gx[i], gy[i], img[i]); // Gradient-assisted estimate | |
| } | |
| else { | |
| dist[i]= 0.0; // Inside the object | |
| } | |
| } | |
| /* Perform the transformation */ | |
| do | |
| { | |
| changed = 0; | |
| /* Scan rows, except first row */ | |
| for(y=1; y<h; y++) | |
| { | |
| /* move index to leftmost pixel of current row */ | |
| i = y*w; | |
| /* scan right, propagate distances from above & left */ | |
| /* Leftmost pixel is special, has no left neighbors */ | |
| olddist = dist[i]; | |
| if(olddist > 0) // If non-zero distance or not set yet | |
| { | |
| c = i + offset_u; // Index of candidate for testing | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_ur; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| i++; | |
| /* Middle pixels have all neighbors */ | |
| for(x=1; x<w-1; x++, i++) | |
| { | |
| olddist = dist[i]; | |
| if(olddist <= 0) continue; // No need to update further | |
| c = i+offset_l; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_lu; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_u; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_ur; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| /* Rightmost pixel of row is special, has no right neighbors */ | |
| olddist = dist[i]; | |
| if(olddist > 0) // If not already zero distance | |
| { | |
| c = i+offset_l; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_lu; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_u; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty+1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| /* Move index to second rightmost pixel of current row. */ | |
| /* Rightmost pixel is skipped, it has no right neighbor. */ | |
| i = y*w + w-2; | |
| /* scan left, propagate distance from right */ | |
| for(x=w-2; x>=0; x--, i--) | |
| { | |
| olddist = dist[i]; | |
| if(olddist <= 0) continue; // Already zero distance | |
| c = i+offset_r; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| } | |
| /* Scan rows in reverse order, except last row */ | |
| for(y=h-2; y>=0; y--) | |
| { | |
| /* move index to rightmost pixel of current row */ | |
| i = y*w + w-1; | |
| /* Scan left, propagate distances from below & right */ | |
| /* Rightmost pixel is special, has no right neighbors */ | |
| olddist = dist[i]; | |
| if(olddist > 0) // If not already zero distance | |
| { | |
| c = i+offset_d; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_dl; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| i--; | |
| /* Middle pixels have all neighbors */ | |
| for(x=w-2; x>0; x--, i--) | |
| { | |
| olddist = dist[i]; | |
| if(olddist <= 0) continue; // Already zero distance | |
| c = i+offset_r; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_rd; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_d; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_dl; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| /* Leftmost pixel is special, has no left neighbors */ | |
| olddist = dist[i]; | |
| if(olddist > 0) // If not already zero distance | |
| { | |
| c = i+offset_r; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_rd; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx-1; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| olddist=newdist; | |
| changed = 1; | |
| } | |
| c = i+offset_d; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx; | |
| newdisty = cdisty-1; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| /* Move index to second leftmost pixel of current row. */ | |
| /* Leftmost pixel is skipped, it has no left neighbor. */ | |
| i = y*w + 1; | |
| for(x=1; x<w; x++, i++) | |
| { | |
| /* scan right, propagate distance from left */ | |
| olddist = dist[i]; | |
| if(olddist <= 0) continue; // Already zero distance | |
| c = i+offset_l; | |
| cdistx = distx[c]; | |
| cdisty = disty[c]; | |
| newdistx = cdistx+1; | |
| newdisty = cdisty; | |
| newdist = DISTAA(c, cdistx, cdisty, newdistx, newdisty); | |
| if(newdist < olddist-epsilon) | |
| { | |
| distx[i]=newdistx; | |
| disty[i]=newdisty; | |
| dist[i]=newdist; | |
| changed = 1; | |
| } | |
| } | |
| } | |
| } | |
| while(changed); // Sweep until no more updates are made | |
| /* The transformation is completed. */ | |
| } | |
| #ifdef __cplusplus | |
| } // extern "C" | |
| #endif //__cplusplus | |
| #ifdef EDTAA3FUNC_HAS_IMGUI_SUPPORT | |
| #include <imgui.h> | |
| namespace ImGuiEdtaaHelper { | |
| // The purpose of TmpData is to allow releasing the memory all togther | |
| // at the end of a multiple call to make_distance_mapb(...)/make_distance_mapd(...) | |
| // [However we don't use this feature here] | |
| struct TmpData { | |
| ImVector<double> v_data; | |
| ImVector<short> v_xdist; | |
| ImVector<short> v_ydist; | |
| ImVector<double> v_gx; | |
| ImVector<double> v_gy; | |
| ImVector<double> v_outside; | |
| ImVector<double> v_inside; | |
| void freeMemory() { | |
| TmpData tmp; | |
| v_data.swap(tmp.v_data); | |
| v_xdist.swap(tmp.v_xdist); | |
| v_ydist.swap(tmp.v_ydist); | |
| v_gx.swap(tmp.v_gx); | |
| v_outside.swap(tmp.v_outside); | |
| v_inside.swap(tmp.v_inside); | |
| } | |
| }; | |
| static TmpData tmpData; | |
| static void FreeTmpMemory() {tmpData.freeMemory();} | |
| // These two methods are adapted from: https://github.com/rougier/freetype-gl (Copyright 2011,2012 Nicolas P. Rougier), | |
| // so that the memory they use can optionally be freed once, after all the glyphs are processed. | |
| static double * make_distance_mapd( double *data, unsigned int width, unsigned int height, TmpData* pOptionalTmpData=NULL) | |
| { | |
| if (!pOptionalTmpData) pOptionalTmpData=&tmpData; | |
| const unsigned int area = width * height; | |
| IM_ASSERT(area>0); | |
| pOptionalTmpData->v_xdist.resize(area); short* xdist = &pOptionalTmpData->v_xdist[0]; | |
| pOptionalTmpData->v_ydist.resize(area); short* ydist = &pOptionalTmpData->v_ydist[0]; | |
| pOptionalTmpData->v_gx.resize(area); double* gx = &pOptionalTmpData->v_gx[0]; | |
| pOptionalTmpData->v_gy.resize(area); double* gy = &pOptionalTmpData->v_gy[0]; | |
| pOptionalTmpData->v_outside.resize(area); double* outside=&pOptionalTmpData->v_outside[0]; | |
| pOptionalTmpData->v_inside.resize(area); double* inside= &pOptionalTmpData->v_inside[0]; | |
| double vmin = DBL_MAX; | |
| unsigned int i; | |
| // Compute outside = edtaa3(bitmap); % Transform background (0's) | |
| computegradient( data, width, height, gx, gy); | |
| edtaa3(data, gx, gy, width, height, xdist, ydist, outside); | |
| for( i=0; i<area; ++i) { | |
| if( outside[i] < 0.0 ) outside[i] = 0.0; | |
| } | |
| // Compute inside = edtaa3(1-bitmap); % Transform foreground (1's) | |
| memset( gx, 0, sizeof(double)*area ); | |
| memset( gy, 0, sizeof(double)*area ); | |
| for( i=0; i<area; ++i) data[i] = 1 - data[i]; | |
| computegradient( data, width, height, gx, gy ); | |
| edtaa3( data, gx, gy, width, height, xdist, ydist, inside ); | |
| for( i=0; i<area; ++i ) { | |
| if( inside[i] < 0 ) inside[i] = 0.0; | |
| } | |
| // distmap = outside - inside; % Bipolar distance field | |
| for( i=0; i<area; ++i) { | |
| outside[i] -= inside[i]; | |
| if( outside[i] < vmin ) vmin = outside[i]; | |
| } | |
| vmin = fabs(vmin); | |
| for( i=0; i<area; ++i) { | |
| double v = outside[i]; | |
| if ( v < -vmin) outside[i] = -vmin; | |
| else if( v > +vmin) outside[i] = +vmin; | |
| data[i] = (outside[i]+vmin)/(2*vmin); | |
| } | |
| return data; | |
| } | |
| static unsigned char * make_distance_mapb(const unsigned char *img,unsigned int width, unsigned int height, unsigned char* imgOutSameSize, TmpData* pOptionalTmpData=NULL) | |
| { | |
| IM_ASSERT(imgOutSameSize); | |
| if (!pOptionalTmpData) pOptionalTmpData=&tmpData; | |
| const unsigned int area = width * height; | |
| IM_ASSERT(area>0); | |
| pOptionalTmpData->v_data.resize(area); | |
| double* data = &pOptionalTmpData->v_data[0]; | |
| unsigned int i; | |
| // find minimimum and maximum values | |
| double img_min = DBL_MAX,img_max = DBL_MIN,v; | |
| for( i=0; i<area; ++i) { | |
| data[i] = v = img[i]; | |
| if (v > img_max) img_max = v; | |
| if (v < img_min) img_min = v; | |
| } | |
| // Map values from 0 - 255 to 0.0 - 1.0 | |
| for( i=0; i<area; ++i) data[i] = (img[i]-img_min)/img_max; | |
| data = make_distance_mapd(data, width, height,pOptionalTmpData); | |
| // map values from 0.0 - 1.0 to 0 - 255 | |
| for( i=0; i<area; ++i) imgOutSameSize[i] = (unsigned char)(255*(1-data[i])); | |
| return imgOutSameSize; | |
| } | |
| } //ImGuiEdtaaHelper | |
| namespace ImGui { | |
| void ProcessAlpha8ImageForSignedDistanceFontEffect(unsigned char* pixels,int w,int h) { | |
| IM_ASSERT(pixels && w>0 && h>0); | |
| ImVector<unsigned char> tmpData;tmpData.resize(w*h); | |
| ImGuiEdtaaHelper::make_distance_mapb(pixels,w,h,&tmpData[0]); | |
| ImGuiEdtaaHelper::FreeTmpMemory(); | |
| memcpy(pixels,&tmpData[0],w*h); | |
| } | |
| void PostBuildForSignedDistanceFontEffect(ImFontAtlas* atlas) { | |
| if (!atlas->TexPixelsAlpha8) atlas->GetTexDataAsAlpha8(&atlas->TexPixelsAlpha8,NULL,NULL); | |
| ProcessAlpha8ImageForSignedDistanceFontEffect(atlas->TexPixelsAlpha8,atlas->TexWidth,atlas->TexHeight); | |
| } | |
| } | |
| #endif //EDTAA3FUNC_HAS_IMGUI_SUPPORT | |
| #endif //EDTAA3FUNC_H_ |
Making further experiments, it seems that the edtaa approach used by freetype_gl is not only much easier, but much better: see some results:
Ubuntu-B.ttf 13 pxls cfg.OversampleH=cfg.OversampleV=1; (16 times less texture memory than in the pic posted above!)
And the default font now works much better too:
All these pics have been taken using the standard stb_truetype.h. Chances are that using the freetype lib we can get even better results.
ROADMAP:
- Although it's trivial, flush all this code and post another one using edtaa.
Some reference code notes for the impatients:
// At the end of a standard Build(ImFontAtlas* atlas) we just need to append something like:
int w,h;
unsigned char* texData;
atlas->GetTexDataAsAlpha8(&texData,&w,&h);
ImVector<unsigned char> tmpData;tmpData.resize(w*h);
ImGuiEdtaaHelper::make_distance_mapb(texData,w,h,&tmpData[0]);
memcpy(texData,&tmpData[0],w*h);
// where make_distance_mapb(...) is a trivial adaptation of the code that uses edtaa3func.c and that can be found here:
// https://github.com/rougier/freetype-gl/blob/master/distance-field.cDONE in Revision 2 😃!
And now it's independent on the "font library" stb_truetype.h (and can be used in imgui_freetype too).
Revision 3
Same as Rev.2, but all embedded in the single file: edtaa3func.h.
See the usage documentation there (however the fragment shader code has been stripped from the comment: you may need to download Rev.2 if you need it).
How do you implement font stroke?
@NewHand007: the fragment shader code has been stripped from the comment: you may need to download Rev.2 if you need it.
sorry ,where can i download "Rev.2" ?
I've been working on font strokes for a few days. Can you share a copy of the code that works my bro?
@NewHand007: the fragment shader code has been stripped from the comment: you may need to download Rev.2 if you need it.
bro
The Rev.2 file with the comment is here
The Rev.2 file with the comment is here
thank you bro !
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Docs are at the top of imguiSdfGenerator.h.
Ubuntu-B.ttf 13 pxls cfg.OversampleH=cfg.OversampleV=4;
[Edit:]: In Rev.1 I used direct calculations on the vectorial shape of the glyphs.
Another (more common) approach, easier to implement, is to simply post-process the normal glyph texture using the file edtaa by Stefan Gustavson. This is used in a lot of projects, such as the popular freetype_gl.