#include "symbols-gl.h" #include #include #include enum { BANDS = 16 }; /* Coordinates travel doubled, so implied points stay whole: 2x of a point * is its raw i16 without the flag, and an implied point's is the sum of its * two neighbours' coordinates. */ #define SHARED \ "#version 310 es\n" \ "precision highp float;\n" \ "precision highp int;\n" static const char vertex_source[] = SHARED "layout(location = 0) in vec4 place; /* origin x, y in pixels; pixels per unit; unused */\n" "layout(location = 1) in vec4 bounds; /* left, bottom, right, top in units */\n" "layout(location = 2) in uint bands; /* its first band */\n" "uniform vec2 target;\n" "out vec2 units;\n" "flat out float scale;\n" "flat out ivec2 rows; /* bottom and top in units */\n" "flat out uint base;\n" "void main() {\n" " vec2 corner = vec2(float(gl_VertexID & 1), float(gl_VertexID >> 1));\n" " vec2 pad = vec2(1.0 / place.z);\n" " units = mix(bounds.xy - pad, bounds.zw + pad, corner);\n" " vec2 pixel = place.xy + vec2(units.x, -units.y) * place.z;\n" " gl_Position = vec4(pixel.x / target.x * 2.0 - 1.0, 1.0 - pixel.y / target.y * 2.0, 0.0, 1.0);\n" " scale = place.z;\n" " rows = ivec2(bounds.yw);\n" " base = bands;\n" "}\n"; static const char fragment_source[] = SHARED "layout(std430, binding = 0) readonly buffer Points { uint points[]; };\n" "layout(std430, binding = 1) readonly buffer Bands { uint bands[]; };\n" "uniform uint listed; /* where the lists of curves start in bands */\n" "in vec2 units;\n" "flat in float scale;\n" "flat in ivec2 rows;\n" "flat in uint base;\n" "out vec4 color;\n" "\n" "ivec3 point(uint i) { /* doubled x, doubled y, off */\n" " uint w = points[i];\n" " int x = int(w << 16u) >> 16, y = int(w) >> 16;\n" " return ivec3(x & ~1, y & ~1, x & 1);\n" "}\n" "int band(int doubled) { /* which of 16 bands a doubled y lies in */\n" " return clamp((doubled - 2 * rows.x) * 16 / (2 * (rows.y - rows.x) + 2), 0, 15);\n" "}\n" "int roots(float a, float b, float c, inout float ts[10], int n) {\n" " float r0 = -1.0, r1 = -1.0;\n" " if (a == 0.0) { if (b != 0.0) r0 = -c / b; }\n" " else {\n" " float d = b * b - 4.0 * a * c;\n" " if (d >= 0.0) {\n" " float q = -0.5 * (b + (b >= 0.0 ? sqrt(d) : -sqrt(d)));\n" " r0 = q / a;\n" " if (q != 0.0) r1 = c / q;\n" " }\n" " }\n" " if (r0 > 0.0 && r0 < 1.0) ts[n++] = r0;\n" " if (r1 > 0.0 && r1 < 1.0) ts[n++] = r1;\n" " return n;\n" "}\n" "/* As curve_area in symbols.c: the curve's share of the pixel [0, 1]^2. */\n" "float area(vec2 p0, vec2 p1, vec2 p2) {\n" " if (max(max(p0.y, p1.y), p2.y) <= 0.0 || min(min(p0.y, p1.y), p2.y) >= 1.0 || min(min(p0.x, p1.x), p2.x) >= 1.0)\n" " return 0.0;\n" " if (max(max(p0.x, p1.x), p2.x) <= 0.0) return clamp(p2.y, 0.0, 1.0) - clamp(p0.y, 0.0, 1.0);\n" " vec2 a = p0 - 2.0 * p1 + p2, b = p0 - p1;\n" " float ts[10];\n" " ts[0] = 0.0;\n" " int n = 1;\n" " n = roots(a.y, -2.0 * b.y, p0.y, ts, n);\n" " n = roots(a.y, -2.0 * b.y, p0.y - 1.0, ts, n);\n" " n = roots(a.x, -2.0 * b.x, p0.x, ts, n);\n" " n = roots(a.x, -2.0 * b.x, p0.x - 1.0, ts, n);\n" " ts[n++] = 1.0;\n" " for (int i = 1; i < n; ++i)\n" " for (int j = i; j > 0 && ts[j] < ts[j - 1]; --j) { float t = ts[j]; ts[j] = ts[j - 1]; ts[j - 1] = t; }\n" " float u0 = 1.0 - p0.x, u1 = 2.0 * b.x, u2 = -a.x, v0 = -2.0 * b.y, v1 = 2.0 * a.y;\n" " float k1 = u0 * v0, k2 = (u0 * v1 + u1 * v0) / 2.0, k3 = (u1 * v1 + u2 * v0) / 3.0, k4 = u2 * v1 / 4.0, sum = 0.0;\n" " for (int i = 0; i + 1 < n; ++i) {\n" " float ta = ts[i], tb = ts[i + 1], t = (ta + tb) / 2.0;\n" " if (tb <= ta) continue;\n" " float y = (a.y * t - 2.0 * b.y) * t + p0.y, x = (a.x * t - 2.0 * b.x) * t + p0.x;\n" " if (y <= 0.0 || y >= 1.0 || x >= 1.0) continue;\n" " if (x <= 0.0) sum += (a.y * tb - 2.0 * b.y) * tb - (a.y * ta - 2.0 * b.y) * ta;\n" " else sum += (((k4 * tb + k3) * tb + k2) * tb + k1) * tb - (((k4 * ta + k3) * ta + k2) * ta + k1) * ta;\n" " }\n" " return sum;\n" "}\n" "void main() {\n" " vec2 corner = units - vec2(0.5 / scale); /* the pixel's lower left, in units */\n" " int b0 = band(2 * int(floor(corner.y))), b1 = band(2 * int(ceil(corner.y + 1.0 / scale)));\n" " float sum = 0.0;\n" " for (int b = b0; b <= b1; ++b) {\n" " uint at = bands[base + 2u * uint(b)], end = at + bands[base + 2u * uint(b) + 1u];\n" " for (; at < end; ++at) {\n" " uint k = bands[listed + at];\n" " ivec3 p = point(k), n = point(k + 1u);\n" " ivec2 s, c, e;\n" " if (p.z == 1) {\n" " ivec3 q = point(k - 1u);\n" " s = q.z == 1 ? (q.xy + p.xy) / 2 : q.xy;\n" " c = p.xy;\n" " e = n.z == 1 ? (p.xy + n.xy) / 2 : n.xy;\n" " } else {\n" " s = p.xy;\n" " c = (p.xy + n.xy) / 2;\n" " e = n.xy;\n" " }\n" " /* a curve over several of this pixel's bands counts in the first */\n" " if (max(band(min(min(s.y, c.y), e.y)), b0) != b) continue;\n" " sum += area((vec2(s) * 0.5 - corner) * scale, (vec2(c) * 0.5 - corner) * scale, (vec2(e) * 0.5 - corner) * scale);\n" " }\n" " }\n" " color = vec4(min(abs(sum), 1.0), 0.0, 0.0, 1.0);\n" "}\n"; static GLuint compile(GLenum type, const char *source, char *error, size_t error_size) { GLuint shader = glCreateShader(type); glShaderSource(shader, 1, &source, NULL); glCompileShader(shader); GLint ok; glGetShaderiv(shader, GL_COMPILE_STATUS, &ok); if (!ok) { glGetShaderInfoLog(shader, (GLsizei)error_size, NULL, error); glDeleteShader(shader); return 0; } return shader; } /* Doubled coordinates make implied points whole; bands as the shader cuts them. */ static int band(int doubled, int bottom, int top) { int b = (doubled - 2 * bottom) * BANDS / (2 * (top - bottom) + 2); return b < 0 ? 0 : b >= BANDS ? BANDS - 1 : b; } bool vega_gl_open(VegaGl *gl, const VegaSymbols *s, char *error, size_t error_size) { *gl = (VegaGl){0}; GLuint vertex = compile(GL_VERTEX_SHADER, vertex_source, error, error_size); GLuint fragment = vertex ? compile(GL_FRAGMENT_SHADER, fragment_source, error, error_size) : 0; if (!fragment) return false; gl->program = glCreateProgram(); glAttachShader(gl->program, vertex); glAttachShader(gl->program, fragment); glLinkProgram(gl->program); glDeleteShader(vertex); glDeleteShader(fragment); GLint ok; glGetProgramiv(gl->program, GL_LINK_STATUS, &ok); if (!ok) { glGetProgramInfoLog(gl->program, (GLsizei)error_size, NULL, error); return false; } /* The point table, as the file has it. */ glGenBuffers(1, &gl->points); glBindBuffer(GL_SHADER_STORAGE_BUFFER, gl->points); glBufferData(GL_SHADER_STORAGE_BUFFER, (GLsizeiptr)(s->points ? s->points : 1) * VEGA_POINT_BYTES, s->bytes + VEGA_SYMBOLS_HEADER + (size_t)s->symbols * VEGA_SYMBOL_BYTES, GL_STATIC_DRAW); /* Bands: per symbol, 16 (start, count) pairs into one list of curves, * each curve (by the point that begins it) in every band it reaches. */ size_t table = (size_t)s->symbols * BANDS * 2, listed = 0; uint32_t *counts = calloc(table + 1, sizeof(*counts)); for (int pass = 0; pass < 2; ++pass) { uint32_t *bands = pass ? malloc((table + listed + 1) * sizeof(*bands)) : NULL; size_t next = 0; for (uint32_t i = 0; i < s->symbols; ++i) { VegaSymbol symbol = vega_symbol_at(s, i); uint32_t *mine = pass ? bands + (size_t)i * BANDS * 2 : counts + (size_t)i * BANDS * 2; if (pass) for (int b = 0; b < BANDS; ++b) { mine[2 * b] = (uint32_t)next; next += counts[(size_t)i * BANDS * 2 + 2 * b + 1]; mine[2 * b + 1] = 0; } VegaCurve c; for (uint32_t k = symbol.first; k < symbol.first + symbol.count; ++k) { if (!vega_symbol_curve(s, &symbol, k, &c)) continue; float low = c.y0 < c.y1 ? c.y0 : c.y1, high = c.y0 > c.y1 ? c.y0 : c.y1; low = c.y2 < low ? c.y2 : low; high = c.y2 > high ? c.y2 : high; int from = band((int)(2 * low), symbol.bottom, symbol.top), to = band((int)(2 * high), symbol.bottom, symbol.top); for (int b = from; b <= to; ++b) { if (pass) bands[table + mine[2 * b] + mine[2 * b + 1]] = k; ++mine[2 * b + 1]; listed += !pass; } } } if (pass) { glGenBuffers(1, &gl->bands); glBindBuffer(GL_SHADER_STORAGE_BUFFER, gl->bands); glBufferData(GL_SHADER_STORAGE_BUFFER, (GLsizeiptr)((table + listed + 1) * sizeof(*bands)), bands, GL_STATIC_DRAW); free(bands); } } free(counts); glGenVertexArrays(1, &gl->array); glGenBuffers(1, &gl->instances); glBindVertexArray(gl->array); glBindBuffer(GL_ARRAY_BUFFER, gl->instances); glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); glEnableVertexAttribArray(2); glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 36, (void *)0); glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 36, (void *)16); glVertexAttribIPointer(2, 1, GL_UNSIGNED_INT, 36, (void *)32); glVertexAttribDivisor(0, 1); glVertexAttribDivisor(1, 1); glVertexAttribDivisor(2, 1); glBindVertexArray(0); glUseProgram(gl->program); glUniform1ui(glGetUniformLocation(gl->program, "listed"), (GLuint)table); gl->viewport = glGetUniformLocation(gl->program, "target"); if (glGetError() != GL_NO_ERROR) { snprintf(error, error_size, "GL error while uploading"); return false; } return true; } void vega_gl_draw(VegaGl *gl, const VegaSymbols *s, const VegaGlyph *glyphs, uint32_t count, int width, int height) { float *instances = malloc((size_t)(count ? count : 1) * 36); for (uint32_t i = 0; i < count; ++i) { VegaSymbol symbol = vega_symbol_at(s, glyphs[i].symbol); float *f = instances + (size_t)i * 9; f[0] = glyphs[i].x, f[1] = glyphs[i].y, f[2] = glyphs[i].scale, f[3] = 0; f[4] = symbol.left, f[5] = symbol.bottom, f[6] = symbol.right, f[7] = symbol.top; uint32_t base = glyphs[i].symbol * BANDS * 2; memcpy(f + 8, &base, 4); } glUseProgram(gl->program); glUniform2f(gl->viewport, (float)width, (float)height); glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, gl->points); glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, gl->bands); glBindVertexArray(gl->array); glBindBuffer(GL_ARRAY_BUFFER, gl->instances); glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)count * 36, instances, GL_STREAM_DRAW); glEnable(GL_BLEND); glBlendFunc(GL_ONE, GL_ONE); glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, (GLsizei)count); glBindVertexArray(0); free(instances); } void vega_gl_close(VegaGl *gl) { glDeleteBuffers(1, &gl->points); glDeleteBuffers(1, &gl->bands); glDeleteBuffers(1, &gl->instances); glDeleteVertexArrays(1, &gl->array); glDeleteProgram(gl->program); *gl = (VegaGl){0}; }