Draft a first working version 🎉

examples/hello.rs

@@ -35,7 +35,13 @@ fn main() -> Result<(), String> {
     context.window().request_redraw();
 
     unsafe {
+        // Enable auto-conversion from/to sRGB
         gl.enable(glow::FRAMEBUFFER_SRGB);
+
+        // Enable alpha blending
+        gl.enable(glow::BLEND);
+        gl.blend_func(glow::SRC_ALPHA, glow::ONE_MINUS_SRC_ALPHA);
+
         gl.clear_color(0.4, 0.4, 0.4, 1.0);
     }
 
@@ -51,13 +57,22 @@ fn main() -> Result<(), String> {
             } => {
                 context.resize(new_size);
 
+                unsafe {
+                    gl.viewport(
+                        0,
+                        0,
+                        new_size.width as _,
+                        new_size.height as _,
+                    );
+                }
+
                 size = new_size;
             }
             glutin::event::Event::RedrawRequested { .. } => {
                 unsafe { gl.clear(glow::COLOR_BUFFER_BIT) }
 
                 glyph_brush.queue(Section {
-                    text: "Hello wgpu_glyph!",
+                    text: "Hello glow_glyph!",
                     screen_position: (30.0, 30.0),
                     color: [0.0, 0.0, 0.0, 1.0],
                     scale: Scale { x: 40.0, y: 40.0 },
@@ -66,7 +81,7 @@ fn main() -> Result<(), String> {
                 });
 
                 glyph_brush.queue(Section {
-                    text: "Hello wgpu_glyph!",
+                    text: "Hello glow_glyph!",
                     screen_position: (30.0, 90.0),
                     color: [1.0, 1.0, 1.0, 1.0],
                     scale: Scale { x: 40.0, y: 40.0 },

src/pipeline.rs

@@ -9,6 +9,7 @@ use glyph_brush::rusttype::{point, Rect};
 pub struct Pipeline {
     sampler: <glow::Context as HasContext>::Sampler,
     program: <glow::Context as HasContext>::Program,
+    vertex_array: <glow::Context as HasContext>::VertexArray,
     instances: <glow::Context as HasContext>::Buffer,
     cache: Cache,
     current_instances: usize,
@@ -25,7 +26,7 @@ impl Pipeline {
         let sampler =
             unsafe { gl.create_sampler().expect("Create glyph sampler") };
 
-        let cache = Cache::new(gl, cache_width, cache_height);
+        let cache = unsafe { Cache::new(gl, cache_width, cache_height) };
 
         let program = unsafe {
             create_program(
@@ -40,17 +41,18 @@ impl Pipeline {
             )
         };
 
-        let instances =
+        let (vertex_array, instances) =
-            unsafe { gl.create_buffer().expect("Create instance buffer") };
+            unsafe { create_instance_buffer(gl, Instance::INITIAL_AMOUNT) };
 
         Pipeline {
             sampler,
             program,
             cache,
+            vertex_array,
             instances,
             current_instances: 0,
             supported_instances: Instance::INITIAL_AMOUNT,
-            current_transform: [0.0; 16],
+            current_transform: IDENTITY_MATRIX,
         }
     }
 
@@ -60,6 +62,36 @@ impl Pipeline {
         transform: [f32; 16],
         region: Option<Region>,
     ) {
+        unsafe {
+            gl.use_program(Some(self.program));
+        }
+
+        if self.current_transform != transform {
+            unsafe {
+                gl.uniform_matrix_4_f32_slice(Some(0), false, &transform);
+            }
+
+            self.current_transform = transform;
+        }
+
+        unsafe {
+            gl.active_texture(glow::TEXTURE0);
+            gl.bind_texture(glow::TEXTURE_2D, Some(self.cache.texture));
+            gl.uniform_1_i32(Some(1), 0);
+
+            gl.bind_vertex_array(Some(self.vertex_array));
+
+            gl.draw_arrays_instanced(
+                glow::TRIANGLE_STRIP,
+                0,
+                4,
+                self.current_instances as i32,
+            );
+
+            gl.bind_vertex_array(None);
+            gl.bind_texture(glow::TEXTURE_2D, None);
+            gl.use_program(None);
+        }
     }
 
     pub fn update_cache(
@@ -69,7 +101,9 @@ impl Pipeline {
         size: [u16; 2],
         data: &[u8],
     ) {
-        self.cache.update(gl, offset, size, data);
+        unsafe {
+            self.cache.update(gl, offset, size, data);
+        }
     }
 
     pub fn increase_cache_size(
@@ -78,7 +112,11 @@ impl Pipeline {
         width: u32,
         height: u32,
     ) {
-        self.cache = Cache::new(gl, width, height);
+        unsafe {
+            self.cache.destroy(gl);
+
+            self.cache = Cache::new(gl, width, height);
+        }
     }
 
     pub fn upload(&mut self, gl: &glow::Context, instances: &[Instance]) {
@@ -88,12 +126,28 @@ impl Pipeline {
         }
 
         if instances.len() > self.supported_instances {
-            // TODO
+            unsafe {
+                gl.delete_buffer(self.instances);
+                gl.delete_vertex_array(self.vertex_array);
+            }
 
+            let (new_vertex_array, new_instances) =
+                unsafe { create_instance_buffer(gl, instances.len()) };
+
+            self.vertex_array = new_vertex_array;
+            self.instances = new_instances;
             self.supported_instances = instances.len();
         }
 
-        // TODO
+        unsafe {
+            gl.bind_buffer(glow::ARRAY_BUFFER, Some(self.instances));
+            gl.buffer_sub_data_u8_slice(
+                glow::ARRAY_BUFFER,
+                0,
+                bytemuck::cast_slice(instances),
+            );
+            gl.bind_buffer(glow::ARRAY_BUFFER, None);
+        }
 
         self.current_instances = instances.len();
     }
@@ -219,3 +273,63 @@ unsafe fn create_program(
 
     program
 }
+
+unsafe fn create_instance_buffer(
+    gl: &glow::Context,
+    size: usize,
+) -> (
+    <glow::Context as HasContext>::VertexArray,
+    <glow::Context as HasContext>::Buffer,
+) {
+    let vertex_array = gl.create_vertex_array().expect("Create vertex array");
+    let buffer = gl.create_buffer().expect("Create instance buffer");
+
+    gl.bind_vertex_array(Some(vertex_array));
+    gl.bind_buffer(glow::ARRAY_BUFFER, Some(buffer));
+    gl.buffer_data_size(
+        glow::ARRAY_BUFFER,
+        (size * std::mem::size_of::<Instance>()) as i32,
+        glow::DYNAMIC_DRAW,
+    );
+
+    let stride = std::mem::size_of::<Instance>() as i32;
+
+    gl.enable_vertex_attrib_array(0);
+    gl.vertex_attrib_pointer_f32(0, 3, glow::FLOAT, false, stride, 0);
+    gl.vertex_attrib_divisor(0, 1);
+
+    gl.enable_vertex_attrib_array(1);
+    gl.vertex_attrib_pointer_f32(1, 2, glow::FLOAT, false, stride, 4 * 3);
+    gl.vertex_attrib_divisor(1, 1);
+
+    gl.enable_vertex_attrib_array(2);
+    gl.vertex_attrib_pointer_f32(2, 2, glow::FLOAT, false, stride, 4 * (3 + 2));
+    gl.vertex_attrib_divisor(2, 1);
+
+    gl.enable_vertex_attrib_array(3);
+    gl.vertex_attrib_pointer_f32(
+        3,
+        2,
+        glow::FLOAT,
+        false,
+        stride,
+        4 * (3 + 2 + 2),
+    );
+    gl.vertex_attrib_divisor(3, 1);
+
+    gl.enable_vertex_attrib_array(4);
+    gl.vertex_attrib_pointer_f32(
+        4,
+        4,
+        glow::FLOAT,
+        false,
+        stride,
+        4 * (3 + 2 + 2 + 2),
+    );
+    gl.vertex_attrib_divisor(4, 1);
+
+    gl.bind_vertex_array(None);
+    gl.bind_buffer(glow::ARRAY_BUFFER, None);
+
+    (vertex_array, buffer)
+}

src/pipeline/cache.rs

@@ -1,15 +1,55 @@
 use glow::HasContext;
 
 pub struct Cache {
-    texture: <glow::Context as HasContext>::Texture,
+    pub(crate) texture: <glow::Context as HasContext>::Texture,
 }
 
 impl Cache {
-    pub fn new(gl: &glow::Context, width: u32, height: u32) -> Cache {
+    pub unsafe fn new(gl: &glow::Context, width: u32, height: u32) -> Cache {
-        let texture = unsafe {
+        gl.pixel_store_i32(glow::UNPACK_ALIGNMENT, 1);
-            let handle = gl.create_texture().expect("Create glyph cache texture");
 
-            gl.tex_storage_2d(handle, 1, glow::R8, width as i32, height as i32);
+        let texture = {
+            let handle =
+                gl.create_texture().expect("Create glyph cache texture");
+
+            gl.bind_texture(glow::TEXTURE_2D, Some(handle));
+
+            #[cfg(debug_assertions)]
+            gl.object_label(glow::TEXTURE, handle, Some("Glyph cache"));
+
+            gl.tex_parameter_i32(
+                glow::TEXTURE_2D,
+                glow::TEXTURE_WRAP_S,
+                glow::CLAMP_TO_EDGE as i32,
+            );
+            gl.tex_parameter_i32(
+                glow::TEXTURE_2D,
+                glow::TEXTURE_WRAP_T,
+                glow::CLAMP_TO_EDGE as i32,
+            );
+            gl.tex_parameter_i32(
+                glow::TEXTURE_2D,
+                glow::TEXTURE_MIN_FILTER,
+                glow::LINEAR as i32,
+            );
+            gl.tex_parameter_i32(
+                glow::TEXTURE_2D,
+                glow::TEXTURE_MAG_FILTER,
+                glow::LINEAR as i32,
+            );
+
+            gl.tex_image_2d(
+                glow::TEXTURE_2D,
+                0,
+                glow::R8 as i32,
+                width as i32,
+                height as i32,
+                0,
+                glow::RED,
+                glow::UNSIGNED_BYTE,
+                None,
+            );
+            gl.bind_texture(glow::TEXTURE_2D, None);
 
             handle
         };
@@ -17,7 +57,34 @@ impl Cache {
         Cache { texture }
     }
 
-    pub fn update(&self, gl: &glow::Context, offset: [u16; 2], size: [u16; 2], data: &[u8]) {
+    pub unsafe fn update(
-        // TODO
+        &self,
+        gl: &glow::Context,
+        offset: [u16; 2],
+        size: [u16; 2],
+        data: &[u8],
+    ) {
+        let [offset_x, offset_y] = offset;
+        let [width, height] = size;
+
+        gl.bind_texture(glow::TEXTURE_2D, Some(self.texture));
+
+        gl.tex_sub_image_2d_u8_slice(
+            glow::TEXTURE_2D,
+            0,
+            i32::from(offset_x),
+            i32::from(offset_y),
+            i32::from(width),
+            i32::from(height),
+            glow::RED,
+            glow::UNSIGNED_BYTE,
+            Some(data),
+        );
+
+        gl.bind_texture(glow::TEXTURE_2D, None);
+    }
+
+    pub unsafe fn destroy(&self, gl: &glow::Context) {
+        gl.delete_texture(self.texture);
     }
 }

src/shader/vertex.vert

@@ -2,11 +2,11 @@
 
 layout(location = 0) uniform mat4 transform;
 
-in vec3 left_top;
+layout(location = 0) in vec3 left_top;
-in vec2 right_bottom;
+layout(location = 1) in vec2 right_bottom;
-in vec2 tex_left_top;
+layout(location = 2) in vec2 tex_left_top;
-in vec2 tex_right_bottom;
+layout(location = 3) in vec2 tex_right_bottom;
-in vec4 color;
+layout(location = 4) in vec4 color;
 
 out vec2 f_tex_pos;
 out vec4 f_color;