getting closer to dumb font rendering

build.zig

@@ -15,10 +15,15 @@ pub fn build(b: *std.build.Builder) !void {
     exe.addPackagePath("glfw", "vendor/mach/glfw/src/main.zig");
     glfw.link(b, exe, .{});
 
+    exe.linkSystemLibrary("epoxy");
+
     const ftlib = try ft.create(b, target, mode, .{});
     ftlib.link(exe);
-
-    exe.linkSystemLibrary("epoxy");
+    // to link to system:
+    // exe.linkSystemLibrary("freetype2");
+    // exe.linkSystemLibrary("libpng");
+    // exe.linkSystemLibrary("bzip2");
+    // ftlib.addIncludeDirs(exe);
 
     // stb if we need it
     // exe.addIncludeDir("vendor/stb");

nix/devshell.nix

@@ -8,8 +8,11 @@
 , vttest
 , zig
 
+, bzip2
 , fontconfig
+, freetype
 , libepoxy
+, libpng
 , libGL
 , libX11
 , libXcursor
@@ -33,10 +36,14 @@
   buildInputs = [
     # TODO: non-linux
   ] ++ lib.optionals stdenv.isLinux [
-    fontconfig
     libepoxy
     libGL
 
+    fontconfig
+    freetype
+    libpng
+    bzip2
+
     libX11
     libXcursor
     libXext

shaders/text.f.glsl

@@ -0,0 +1,9 @@
+#version 120
+
+varying vec2 texcoord;
+uniform sampler2D tex;
+uniform vec4 color;
+
+void main(void) {
+  gl_FragColor = vec4(1, 1, 1, texture2D(tex, texcoord).r) * color;
+}

shaders/text.v.glsl

@@ -0,0 +1,9 @@
+#version 120
+
+attribute vec4 coord;
+varying vec2 texcoord;
+
+void main(void) {
+  gl_Position = vec4(coord.xy, 0, 1);
+  texcoord = coord.zw;
+}

src/App.zig

@@ -4,8 +4,9 @@
 const App = @This();
 
 const std = @import("std");
-const gl = @import("opengl.zig");
 const glfw = @import("glfw");
+const gl = @import("opengl.zig");
+const TextRenderer = @import("TextRenderer.zig");
 
 const log = std.log;
 
@@ -17,7 +18,11 @@ vao: gl.VertexArray,
 /// Initialize the main app instance. This creates the main window, sets
 /// up the renderer state, compiles the shaders, etc. This is the primary
 /// "startup" logic.
-pub fn init() !App {
+pub fn init(alloc: std.mem.Allocator) !App {
+    // Setup our text renderer
+    var texter = try TextRenderer.init(alloc);
+    defer texter.deinit();
+
     // Create our window
     const window = try glfw.Window.create(640, 480, "ghostty", null, null, .{
         .context_version_major = 3,
@@ -39,6 +44,10 @@ pub fn init() !App {
         }
     }).callback);
 
+    // Blending for text
+    gl.c.glEnable(gl.c.GL_BLEND);
+    gl.c.glBlendFunc(gl.c.GL_SRC_ALPHA, gl.c.GL_ONE_MINUS_SRC_ALPHA);
+
     // Compile our shaders
     const vs = try gl.Shader.create(gl.c.GL_VERTEX_SHADER);
     try vs.setSourceAndCompile(vs_source);

src/TextRenderer.zig

@@ -0,0 +1,116 @@
+const TextRenderer = @This();
+
+const std = @import("std");
+const ftc = @import("freetype/c.zig");
+const gl = @import("opengl.zig");
+
+alloc: std.mem.Allocator,
+ft: ftc.FT_Library,
+face: ftc.FT_Face,
+chars: CharList,
+
+const CharList = std.ArrayListUnmanaged(Char);
+const Char = struct {
+    tex: gl.Texture,
+    size: @Vector(2, c_uint),
+    bearing: @Vector(2, c_int),
+    advance: c_uint,
+};
+
+pub fn init(alloc: std.mem.Allocator) !TextRenderer {
+    var ft: ftc.FT_Library = undefined;
+    if (ftc.FT_Init_FreeType(&ft) != 0) {
+        return error.FreetypeInitFailed;
+    }
+
+    var face: ftc.FT_Face = undefined;
+    if (ftc.FT_New_Memory_Face(
+        ft,
+        face_ttf,
+        face_ttf.len,
+        0,
+        &face,
+    ) != 0) {
+        return error.FreetypeFaceFailed;
+    }
+
+    _ = ftc.FT_Set_Pixel_Sizes(face, 0, 48);
+
+    // disable byte-alignment restriction
+    gl.c.glPixelStorei(gl.c.GL_UNPACK_ALIGNMENT, 1);
+
+    // Pre-render all the ASCII characters
+    var chars = try CharList.initCapacity(alloc, 128);
+    var i: usize = 0;
+    while (i < chars.capacity) : (i += 1) {
+        // Load the character
+        if (ftc.FT_Load_Char(face, i, ftc.FT_LOAD_RENDER) != 0) {
+            return error.GlyphLoadFailed;
+        }
+
+        if (face.*.glyph.*.bitmap.buffer == null) {
+            // Unrenderable characters
+            chars.appendAssumeCapacity(.{
+                .tex = undefined,
+                .size = undefined,
+                .bearing = undefined,
+                .advance = undefined,
+            });
+            continue;
+        }
+
+        // Generate the texture
+        const tex = try gl.Texture.create();
+        var binding = try tex.bind(gl.c.GL_TEXTURE_2D);
+        defer binding.unbind();
+        try binding.image2D(
+            0,
+            gl.c.GL_RED,
+            @intCast(c_int, face.*.glyph.*.bitmap.width),
+            @intCast(c_int, face.*.glyph.*.bitmap.rows),
+            0,
+            gl.c.GL_RED,
+            gl.c.GL_UNSIGNED_BYTE,
+            face.*.glyph.*.bitmap.buffer,
+        );
+        try binding.parameter(gl.c.GL_TEXTURE_WRAP_S, gl.c.GL_CLAMP_TO_EDGE);
+        try binding.parameter(gl.c.GL_TEXTURE_WRAP_T, gl.c.GL_CLAMP_TO_EDGE);
+        try binding.parameter(gl.c.GL_TEXTURE_MIN_FILTER, gl.c.GL_LINEAR);
+        try binding.parameter(gl.c.GL_TEXTURE_MAG_FILTER, gl.c.GL_LINEAR);
+
+        // Store the character
+        chars.appendAssumeCapacity(.{
+            .tex = tex,
+            .size = .{
+                face.*.glyph.*.bitmap.width,
+                face.*.glyph.*.bitmap.rows,
+            },
+            .bearing = .{
+                face.*.glyph.*.bitmap_left,
+                face.*.glyph.*.bitmap_top,
+            },
+            .advance = @intCast(c_uint, face.*.glyph.*.advance.x),
+        });
+    }
+
+    return TextRenderer{
+        .alloc = alloc,
+        .ft = ft,
+        .face = face,
+        .chars = chars,
+    };
+}
+
+pub fn deinit(self: *TextRenderer) void {
+    // TODO: delete textures
+    self.chars.deinit(self.alloc);
+
+    if (ftc.FT_Done_Face(self.face) != 0)
+        std.log.err("freetype face deinitialization failed", .{});
+    if (ftc.FT_Done_FreeType(self.ft) != 0)
+        std.log.err("freetype library deinitialization failed", .{});
+
+    self.* = undefined;
+}
+
+const face_ttf = @embedFile("../fonts/Inconsolata-Regular.ttf");

src/freetype/build.zig

@@ -7,6 +7,7 @@ pub const Library = struct {
     /// statically link this library into the given step
     pub fn link(self: Library, other: *std.build.LibExeObjStep) void {
         self.addIncludeDirs(other);
+        other.addIncludeDir(include_dir);
         other.linkLibrary(self.step);
     }
 
@@ -15,7 +16,6 @@ pub const Library = struct {
     /// library.
     pub fn addIncludeDirs(self: Library, other: *std.build.LibExeObjStep) void {
         _ = self;
-        other.addIncludeDir(include_dir);
 
         // We need to add this directory to the include path for the final
         // app so that we can access "freetype-zig.h".

src/main.zig

@@ -1,18 +1,19 @@
 const std = @import("std");
 const glfw = @import("glfw");
-const gl = @import("opengl.zig");
-const stb = @import("stb.zig");
-const fonts = @import("fonts.zig");
 
 const App = @import("App.zig");
 
 pub fn main() !void {
+    var general_purpose_allocator = std.heap.GeneralPurposeAllocator(.{}){};
+    const gpa = general_purpose_allocator.allocator();
+    defer _ = general_purpose_allocator.deinit();
+
     // List our fonts
     try glfw.init(.{});
     defer glfw.terminate();
 
     // Run our app
-    var app = try App.init();
+    var app = try App.init(gpa);
     defer app.deinit();
     try app.run();
 }