really hacked in emoji support, time to clean it up

shaders/cell.f.glsl

@@ -18,6 +18,7 @@ layout(location = 0) out vec4 out_FragColor;
 
 // Font texture
 uniform sampler2D text;
+uniform sampler2D text_color;
 
 // Dimensions of the cell
 uniform vec2 cell_size;
@@ -25,22 +26,29 @@ uniform vec2 cell_size;
 // See vertex shader
 const uint MODE_BG = 1u;
 const uint MODE_FG = 2u;
+const uint MODE_FG_COLOR = 7u;
 const uint MODE_CURSOR_RECT = 3u;
 const uint MODE_CURSOR_RECT_HOLLOW = 4u;
 const uint MODE_CURSOR_BAR = 5u;
 const uint MODE_UNDERLINE = 6u;
 
 void main() {
+    float a;
+
     switch (mode) {
     case MODE_BG:
         out_FragColor = color;
         break;
 
     case MODE_FG:
-        float a = texture(text, glyph_tex_coords).r;
+        a = texture(text, glyph_tex_coords).r;
         out_FragColor = vec4(color.rgb, color.a*a);
         break;
 
+    case MODE_FG_COLOR:
+        out_FragColor = texture(text_color, glyph_tex_coords);
+        break;
+
     case MODE_CURSOR_RECT:
         out_FragColor = color;
         break;

shaders/cell.v.glsl

@@ -6,6 +6,7 @@
 // NOTE: this must be kept in sync with the fragment shader
 const uint MODE_BG = 1u;
 const uint MODE_FG = 2u;
+const uint MODE_FG_COLOR = 7u;
 const uint MODE_CURSOR_RECT = 3u;
 const uint MODE_CURSOR_RECT_HOLLOW = 4u;
 const uint MODE_CURSOR_BAR = 5u;
@@ -50,6 +51,7 @@ flat out vec2 screen_cell_pos;
 flat out uint mode;
 
 uniform sampler2D text;
+uniform sampler2D text_color;
 uniform vec2 cell_size;
 uniform mat4 projection;
 uniform float glyph_baseline;
@@ -113,20 +115,41 @@ void main() {
         break;
 
     case MODE_FG:
+    case MODE_FG_COLOR:
+        vec2 glyph_offset_calc = glyph_offset;
+
+        // If the glyph is larger than our cell, we need to downsample it
+        // TODO: for now, we assume this means it is a full width character
+        // TODO: in the future, use unicode libs to verify this.
+        vec2 glyph_size_downsampled = glyph_size;
+        if (glyph_size.x > cell_size.x) {
+            glyph_size_downsampled.x = cell_size.x * 2;
+            glyph_size_downsampled.y = glyph_size.y * (glyph_size_downsampled.x / glyph_size.x);
+            glyph_offset_calc.y = glyph_offset.y * (glyph_size_downsampled.x / glyph_size.x);
+        }
+
         // The glyph_offset.y is the y bearing, a y value that when added
         // to the baseline is the offset (+y is up). Our grid goes down.
         // So we flip it with `cell_size.y - glyph_offset.y`. The glyph_baseline
         // uniform sets our line baseline where characters "sit".
-        vec2 glyph_offset_calc = glyph_offset;
+        glyph_offset_calc.y = cell_size.y - glyph_offset_calc.y - glyph_baseline;
-        glyph_offset_calc.y = cell_size.y - glyph_offset.y - glyph_baseline;
 
         // Calculate the final position of the cell.
-        cell_pos = cell_pos + glyph_size * position + glyph_offset_calc;
+        cell_pos = cell_pos + glyph_size_downsampled * position + glyph_offset_calc;
         gl_Position = projection * vec4(cell_pos, cell_z, 1.0);
 
         // We need to convert our texture position and size to normalized
         // device coordinates (0 to 1.0) by dividing by the size of the texture.
-        ivec2 text_size = textureSize(text, 0);
+        ivec2 text_size;
+        switch(mode_in) {
+        case MODE_FG:
+            text_size = textureSize(text, 0);
+            break;
+
+        case MODE_FG_COLOR:
+            text_size = textureSize(text_color, 0);
+            break;
+        }
         vec2 glyph_tex_pos = glyph_pos / text_size;
         vec2 glyph_tex_size = glyph_size / text_size;
         glyph_tex_coords = glyph_tex_pos + glyph_tex_size * position;

src/Grid.zig

@@ -42,9 +42,11 @@ vao: gl.VertexArray,
 ebo: gl.Buffer,
 vbo: gl.Buffer,
 texture: gl.Texture,
+texture_color: gl.Texture,
 
 /// The font atlas.
 font_atlas: font.Family,
+font_emoji: font.Family,
 atlas_dirty: bool,
 
 /// Whether the cursor is visible or not. This is used to control cursor
@@ -160,6 +162,13 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
     );
     log.debug("cell dimensions w={d} h={d} baseline={d}", .{ cell_width, cell_height, cell_baseline });
 
+    // Load our emoji font
+    var atlas_color = try Atlas.init(alloc, 512, .rgba);
+    errdefer atlas_color.deinit(alloc);
+    var fam_emoji = try font.Family.init(atlas_color);
+    errdefer fam_emoji.deinit(alloc);
+    try fam_emoji.loadFaceFromMemory(.regular, face_emoji_ttf, config.@"font-size");
+
     // Create our shader
     const program = try gl.Program.createVF(
         @embedFile("../shaders/cell.v.glsl"),
@@ -172,6 +181,10 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
     try program.setUniform("cell_size", @Vector(2, f32){ cell_width, cell_height });
     try program.setUniform("glyph_baseline", cell_baseline);
 
+    // Set all of our texture indexes
+    try program.setUniform("text", 0);
+    try program.setUniform("text_emoji", 1);
+
     // Setup our VAO
     const vao = try gl.VertexArray.create();
     errdefer vao.destroy();
@@ -225,6 +238,7 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
     // Build our texture
     const tex = try gl.Texture.create();
     errdefer tex.destroy();
+    {
         const texbind = try tex.bind(.@"2D");
         try texbind.parameter(.WrapS, gl.c.GL_CLAMP_TO_EDGE);
         try texbind.parameter(.WrapT, gl.c.GL_CLAMP_TO_EDGE);
@@ -240,6 +254,28 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
             .UnsignedByte,
             atlas.data.ptr,
         );
+    }
+
+    // Build our color texture
+    const tex_color = try gl.Texture.create();
+    errdefer tex_color.destroy();
+    {
+        const texbind = try tex_color.bind(.@"2D");
+        try texbind.parameter(.WrapS, gl.c.GL_CLAMP_TO_EDGE);
+        try texbind.parameter(.WrapT, gl.c.GL_CLAMP_TO_EDGE);
+        try texbind.parameter(.MinFilter, gl.c.GL_LINEAR);
+        try texbind.parameter(.MagFilter, gl.c.GL_LINEAR);
+        try texbind.image2D(
+            0,
+            .RGBA,
+            @intCast(c_int, atlas_color.size),
+            @intCast(c_int, atlas_color.size),
+            0,
+            .BGRA,
+            .UnsignedByte,
+            atlas_color.data.ptr,
+        );
+    }
 
     return Grid{
         .alloc = alloc,
@@ -251,7 +287,9 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
         .ebo = ebo,
         .vbo = vbo,
         .texture = tex,
+        .texture_color = tex_color,
         .font_atlas = fam,
+        .font_emoji = fam_emoji,
         .atlas_dirty = false,
         .cursor_visible = true,
         .cursor_style = .box,
@@ -263,7 +301,10 @@ pub fn init(alloc: Allocator, config: *const Config) !Grid {
 pub fn deinit(self: *Grid) void {
     self.font_atlas.atlas.deinit(self.alloc);
     self.font_atlas.deinit(self.alloc);
+    self.font_emoji.atlas.deinit(self.alloc);
+    self.font_emoji.deinit(self.alloc);
     self.texture.destroy();
+    self.texture_color.destroy();
     self.vbo.destroy();
     self.ebo.destroy();
     self.vao.destroy();
@@ -456,17 +497,32 @@ pub fn updateCell(
         else
             .regular;
 
-        // Get our glyph
+        var mode: u8 = 2; // MODE_FG
-        // TODO: if we add a glyph, I think we need to rerender the texture.
+
+        // Get our glyph. Try our normal font atlas first.
         const glyph = if (self.font_atlas.getGlyph(cell.char, style)) |glyph|
             glyph
         else glyph: {
             self.atlas_dirty = true;
-            break :glyph try self.font_atlas.addGlyph(self.alloc, cell.char, style);
+            break :glyph self.font_atlas.addGlyph(
+                self.alloc,
+                cell.char,
+                style,
+            ) catch |err| switch (err) {
+                error.GlyphNotFound => not_found: {
+                    mode = 7; // MODE_FG_COLOR
+                    break :not_found try self.font_emoji.addGlyph(
+                        self.alloc,
+                        cell.char,
+                        style,
+                    );
+                },
+                else => return err,
+            };
         };
 
         self.cells.appendAssumeCapacity(.{
-            .mode = 2,
+            .mode = mode,
             .grid_col = @intCast(u16, x),
             .grid_row = @intCast(u16, y),
             .glyph_x = glyph.atlas_x,
@@ -537,6 +593,7 @@ pub fn setScreenSize(self: *Grid, dim: ScreenSize) !void {
 
 /// Updates the font texture atlas if it is dirty.
 fn flushAtlas(self: *Grid) !void {
+    {
         var texbind = try self.texture.bind(.@"2D");
         defer texbind.unbind();
         try texbind.subImage2D(
@@ -549,6 +606,22 @@ fn flushAtlas(self: *Grid) !void {
             .UnsignedByte,
             self.font_atlas.atlas.data.ptr,
         );
+    }
+
+    {
+        var texbind = try self.texture_color.bind(.@"2D");
+        defer texbind.unbind();
+        try texbind.subImage2D(
+            0,
+            0,
+            0,
+            @intCast(c_int, self.font_emoji.atlas.size),
+            @intCast(c_int, self.font_emoji.atlas.size),
+            .BGRA,
+            .UnsignedByte,
+            self.font_emoji.atlas.data.ptr,
+        );
+    }
 }
 
 /// Render renders the current cell state. This will not modify any of
@@ -603,11 +676,15 @@ pub fn render(self: *Grid) !void {
         assert(self.gl_cells_written <= self.cells.items.len);
     }
 
-    // Bind our texture
+    // Bind our textures
     try gl.Texture.active(gl.c.GL_TEXTURE0);
     var texbind = try self.texture.bind(.@"2D");
     defer texbind.unbind();
 
+    try gl.Texture.active(gl.c.GL_TEXTURE1);
+    var texbind1 = try self.texture_color.bind(.@"2D");
+    defer texbind1.unbind();
+
     try gl.drawElementsInstanced(
         gl.c.GL_TRIANGLES,
         6,
@@ -686,3 +763,4 @@ test "GridSize update rounding" {
 
 const face_ttf = @embedFile("font/res/FiraCode-Regular.ttf");
 const face_bold_ttf = @embedFile("font/res/FiraCode-Bold.ttf");
+const face_emoji_ttf = @embedFile("font/res/NotoColorEmoji.ttf");

src/font/Face.zig

@@ -98,9 +98,7 @@ pub fn loadGlyph(self: Face, alloc: Allocator, atlas: *Atlas, cp: u32) !Glyph {
 
         // Unknown glyph.
         log.warn("glyph not found: {x}", .{cp});
-
+        return error.GlyphNotFound;
-        // TODO: render something more identifiable than a space
-        break :glyph_index ftc.FT_Get_Char_Index(self.ft_face, ' ');
     };
     //log.warn("glyph index: {}", .{glyph_index});
 

src/opengl/Texture.zig

@@ -47,6 +47,7 @@ pub const Parameter = enum(c_uint) {
 /// Internal format enum for texture images.
 pub const InternalFormat = enum(c_int) {
     Red = c.GL_RED,
+    RGBA = c.GL_RGBA,
 
     // There are so many more that I haven't filled in.
     _,
@@ -55,6 +56,7 @@ pub const InternalFormat = enum(c_int) {
 /// Format for texture images
 pub const Format = enum(c_uint) {
     Red = c.GL_RED,
+    BGRA = c.GL_BGRA,
 
     // There are so many more that I haven't filled in.
     _,