| static const char *hb_gpu_vertex_wgsl = |
| "/*\n" |
| " * Copyright (C) 2026 Behdad Esfahbod\n" |
| " * Copyright (C) 2017 Eric Lengyel\n" |
| " *\n" |
| " * Based on the Slug algorithm by Eric Lengyel:\n" |
| " * https://github.com/EricLengyel/Slug\n" |
| " *\n" |
| " * This is part of HarfBuzz, a text shaping library.\n" |
| " *\n" |
| " * Permission is hereby granted, without written agreement and without\n" |
| " * license or royalty fees, to use, copy, modify, and distribute this\n" |
| " * software and its documentation for any purpose, provided that the\n" |
| " * above copyright notice and the following two paragraphs appear in\n" |
| " * all copies of this software.\n" |
| " *\n" |
| " * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR\n" |
| " * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES\n" |
| " * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN\n" |
| " * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH\n" |
| " * DAMAGE.\n" |
| " *\n" |
| " * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,\n" |
| " * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND\n" |
| " * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS\n" |
| " * ON AN \"AS IS\" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO\n" |
| " * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.\n" |
| " */\n" |
| "\n" |
| "\n" |
| "/* Requires WGSL (WebGPU Shading Language). */\n" |
| "\n" |
| "\n" |
| "/* Dilate a glyph vertex by half a pixel on screen.\n" |
| " *\n" |
| " * position: object-space vertex position (modified in place)\n" |
| " * texcoord: em-space sample coordinates (modified in place)\n" |
| " * normal: object-space outward normal at this vertex\n" |
| " * jac: inverse of the 2x2 linear part of the em-to-object transform,\n" |
| " * stored row-major as (j00, j01, j10, j11). Maps object-space\n" |
| " * displacements back to em-space for texcoord adjustment.\n" |
| " * For simple scaling with y-flip (the common case):\n" |
| " * em-to-object = [[s, 0], [0, -s]]\n" |
| " * jac = (1/s, 0, 0, -1/s)\n" |
| " * m: model-view-projection matrix\n" |
| " * viewport: viewport size in pixels\n" |
| " *\n" |
| " * Returns (new_position, new_texcoord).\n" |
| " */\n" |
| "fn hb_gpu_dilate (position: vec2f, texcoord: vec2f,\n" |
| " normal: vec2f, jac: vec4f,\n" |
| " m: mat4x4f, viewport: vec2f) -> array<vec2f, 2>\n" |
| "{\n" |
| " let n = normalize (normal);\n" |
| "\n" |
| " let clipPos = m * vec4f (position, 0.0, 1.0);\n" |
| " let clipN = m * vec4f (n, 0.0, 0.0);\n" |
| "\n" |
| " let s = clipPos.w;\n" |
| " let t = clipN.w;\n" |
| "\n" |
| " let u = (s * clipN.x - t * clipPos.x) * viewport.x;\n" |
| " let v = (s * clipN.y - t * clipPos.y) * viewport.y;\n" |
| "\n" |
| " let s2 = s * s;\n" |
| " let st = s * t;\n" |
| " let uv = u * u + v * v;\n" |
| "\n" |
| " let denom = uv - st * st;\n" |
| " var d: f32;\n" |
| " if (abs (denom) > 1.0 / 16777216.0) {\n" |
| " d = s2 * (st + sqrt (uv)) / denom;\n" |
| " } else {\n" |
| " d = 0.0;\n" |
| " }\n" |
| "\n" |
| " let dPos = d * normal;\n" |
| " return array<vec2f, 2> (\n" |
| " position + dPos,\n" |
| " texcoord + vec2f (dot (dPos, jac.xy), dot (dPos, jac.zw))\n" |
| " );\n" |
| "}\n" |
| ; |
