Render outlined text with dft.

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "modules/glamour"]
 	path = modules/glamour
 	url = git://github.com/Dav1dde/glamour
+[submodule "modules/dft"]
+	path = modules/dft
+	url = ../../dft.git

Rsconscript

@@ -1,5 +1,6 @@
 configure do
   check_d_compiler
+  check_cfg package: "freetype2"
 end
 
 build do
@@ -12,8 +13,9 @@ build do
       "modules/DerelictGL3/source",
       "modules/gl3n/gl3n",
       "modules/glamour/glamour",
+      "modules/dft/src",
     ].each do |dir|
-      sources += glob("#{dir}/**/*.d")
+      sources += glob("#{dir}/**/*.{d,c}")
     end
     env["D_IMPORT_PATH"] += [
       "modules/DerelictUtil/source",
@@ -21,6 +23,7 @@ build do
       "modules/DerelictGL3/source",
       "modules/gl3n",
       "modules/glamour",
+      "modules/dft/src",
     ]
     env["DFLAGS"] += ["-fversion=Derelict3", "-fversion=gl3n", "-fversion=SDLImage2"]
     env["LDFLAGS"] += ["-static-libgcc"]

modules/dft

@@ -0,0 +1 @@
+Subproject commit 4a0727b535bb3164e48c6bb57194f737dfeb0aab

src/app.d

@@ -1,24 +1,142 @@
 import std.stdio;
+import core.stdc.string;
 import derelict.sdl2.sdl;
 import derelict.opengl3.gl3;
 import glamour.vao;
 import glamour.shader;
 import glamour.vbo;
+import glamour.texture;
 import gl3n.linalg;
+static import dft;
 
 enum int WIDTH = 800;
 enum int HEIGHT = 600;
 
+Shader spinny_program;
 GLint position_idx;
 GLint color_idx;
 GLint view_idx;
+Shader font_program;
+GLint font_coords_idx;
+GLint font_viewport_size_idx;
+GLint font_position_idx;
+GLint font_texture_idx;
+GLint font_color_idx;
 mat4 view_matrix;
 
+private uint next_power_of_2(uint n)
+{
+    n--;
+    n |= n >> 1u;
+    n |= n >> 2u;
+    n |= n >> 4u;
+    n |= n >> 8u;
+    n |= n >> 16u;
+    n++;
+    return n;
+}
+
+class Glyph
+{
+    Texture2D m_texture;
+    VAO m_vao;
+    Buffer m_vbo;
+    int m_advance;
+
+    this(dft.Font font, uint char_code, int outline_size)
+    {
+        dft.Font.Glyph dft_glyph = font.get_glyph(char_code, outline_size);
+        m_advance = dft_glyph.advance;
+
+        m_texture = new Texture2D();
+        uint rwidth = next_power_of_2(dft_glyph.width);
+        uint rheight = next_power_of_2(dft_glyph.height);
+        ubyte[] texture_data = new ubyte[rwidth * rheight];
+        for (uint row = 0u; row < dft_glyph.height; row++)
+        {
+            memcpy(&texture_data[row * rwidth],
+                   &dft_glyph.bitmap[(dft_glyph.height - row - 1) * dft_glyph.width],
+                   dft_glyph.width);
+        }
+        m_texture.bind();
+        m_texture.set_parameter(GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        m_texture.set_parameter(GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        m_texture.set_parameter(GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        m_texture.set_parameter(GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        m_texture.set_data(texture_data, GL_ALPHA, rwidth, rheight, GL_ALPHA, GL_UNSIGNED_BYTE, false);
+
+        m_vao = new VAO();
+        m_vao.bind();
+
+        int left = dft_glyph.left;
+        int top = dft_glyph.top;
+        float s_max = dft_glyph.width / cast(float)rwidth;
+        float t_max = dft_glyph.height / cast(float)rheight;
+        GLfloat[] data = [
+            cast(GLfloat)left, cast(GLfloat)(top - dft_glyph.height), 0.0, 0.0,
+            cast(GLfloat)(left + dft_glyph.width), cast(GLfloat)(top - dft_glyph.height), s_max, 0.0,
+            cast(GLfloat)left, cast(GLfloat)top, 0.0, t_max,
+            cast(GLfloat)(left + dft_glyph.width), cast(GLfloat)top, s_max, t_max,
+        ];
+        m_vbo = new Buffer(data);
+        m_vbo.bind();
+
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, null);
+    }
+
+    void render()
+    {
+        m_vao.bind();
+        m_texture.bind();
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    }
+
+    @property int advance()
+    {
+        return m_advance;
+    }
+}
+
+class OutlinedGlyph
+{
+    Glyph m_outline_glyph;
+    Glyph m_inner_glyph;
+
+    this(dft.Font font, uint char_code, int outline_size)
+    {
+        m_outline_glyph = new Glyph(font, char_code, outline_size);
+        m_inner_glyph = new Glyph(font, char_code, 0);
+    }
+
+    void render()
+    {
+        glUniform4f(font_color_idx, 0.0, 0.0, 0.0, 1.0);
+        m_outline_glyph.render();
+        glUniform4f(font_color_idx, 1.0, 1.0, 1.0, 1.0);
+        m_inner_glyph.render();
+    }
+
+    @property int advance()
+    {
+        return m_inner_glyph.advance;
+    }
+}
+
+dft.Font font;
+VAO spinny_vao;
+
 void init()
 {
+    glActiveTexture(GL_TEXTURE0);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
     glClearColor (1.0, 0.7, 0.0, 0.0);
     glViewport(0, 0, WIDTH, HEIGHT);
     immutable string shader_src = `
+#version 130
+
 vertex:
     uniform mat4 view;
     in vec2 position;
@@ -36,11 +154,12 @@ fragment:
         gl_FragColor = vec4(color_i, 1.0);
     }
         `;
-    VAO vao = new VAO();
+    spinny_vao = new VAO();
-    Shader program = new Shader("program", shader_src);
+    spinny_vao.bind();
-    program.bind();
+    spinny_program = new Shader("spinny_program", shader_src);
-    position_idx = program.get_attrib_location("position");
+    spinny_program.bind();
-    color_idx = program.get_attrib_location("color");
+    position_idx = spinny_program.get_attrib_location("position");
+    color_idx = spinny_program.get_attrib_location("color");
     float[] vertices = [0.4, 0.4, -0.4, 0.4, -0.4, -0.4, 0.4, -0.4];
     float[] colors = [1.0, 0.0, 0.0,  0.0, 1.0, 0.0,  0.0, 0.0, 1.0,  1.0, 1.0, 1.0];
     ushort[] indices = [0, 1, 2, 3];
@@ -54,19 +173,102 @@ fragment:
     glVertexAttribPointer(color_idx, 3, GL_FLOAT, GL_FALSE, 0, null);
     ElementBuffer ibo = new ElementBuffer(indices);
     ibo.bind();
-    view_idx = program.get_uniform_location("view");
+    view_idx = spinny_program.get_uniform_location("view");
+
+    font = new dft.Font("assets/FreeSans.ttf", 60);
+    immutable string font_shader_src = `
+#version 130
+
+vertex:
+    /* Viewport width and height */
+    uniform ivec2 viewport_size;
+    /* Position of lower left corner of glyph */
+    uniform ivec2 position;
+
+    /* Vertex coordinates: x, y, s, t */
+    in vec4 coords;
+
+    /* Output texture coordinate: s, t */
+    out vec2 texture_coord_v;
+
+    /**
+     * Map coordinates such that:
+     * (0 .. viewport_size.[xy]) => (-1.0 .. 1.0)
+     */
+    vec2 map_to_screen(vec2 position)
+    {
+        return 2.0 * position / viewport_size - 1.0;
+    }
+
+    void main(void)
+    {
+        gl_Position = vec4(map_to_screen(vec2(position) + coords.xy), 0, 1);
+        texture_coord_v = coords.zw;
+    }
+
+fragment:
+    /* Texture coordinate: s, t */
+    in vec2 texture_coord_v;
+
+    /* Texture unit */
+    uniform sampler2D texture;
+    uniform vec4 color;
+
+    out vec4 frag_color;
+
+    void main(void)
+    {
+        frag_color = vec4(1, 1, 1, texture2D(texture, texture_coord_v).a) * color;
+    }
+        `;
+    font_program = new Shader("fontshader", font_shader_src);
+    font_program.bind();
+    font_coords_idx = font_program.get_attrib_location("coords");
+    font_viewport_size_idx = font_program.get_uniform_location("viewport_size");
+    font_position_idx = font_program.get_uniform_location("position");
+    font_texture_idx = font_program.get_uniform_location("texture");
+    font_color_idx = font_program.get_uniform_location("color");
+    glUniform2i(font_viewport_size_idx, WIDTH, HEIGHT);
+    glUniform1i(font_texture_idx, 0);
+}
+
+OutlinedGlyph[uint] outlined_glyphs;
+
+OutlinedGlyph get_glyph(uint char_code)
+{
+    if (char_code in outlined_glyphs)
+    {
+        return outlined_glyphs[char_code];
+    }
+    return outlined_glyphs[char_code] = new OutlinedGlyph(font, char_code, 80);
+}
+
+void draw_string(int x, int y, string s)
+{
+    foreach (c; s)
+    {
+        glUniform2i(font_position_idx, x, y);
+        OutlinedGlyph outlined_glyph = get_glyph(c);
+        outlined_glyph.render();
+        x += outlined_glyph.advance;
+    }
 }
 
 void display(SDL_Window * window)
 {
     glClear(GL_COLOR_BUFFER_BIT);
 
+    spinny_program.bind();
+    spinny_vao.bind();
     view_matrix.make_identity();
     view_matrix.rotatez(SDL_GetTicks() / 500.0);
     view_matrix.scale(HEIGHT / cast(float)WIDTH, 1.0, 1.0);
     glUniformMatrix4fv(view_idx, 1, GL_TRUE, view_matrix.value_ptr);
     glDrawElements(GL_TRIANGLE_FAN, 4, GL_UNSIGNED_SHORT, null);
 
+    font_program.bind();
+    draw_string(40, 40, "Hello world!");
+
     SDL_GL_SwapWindow(window);
 }