Get things basically working

examples/generate-atlas.rs

@@ -13,7 +13,7 @@ use compute_shader::buffer;
 use compute_shader::instance::Instance;
 use compute_shader::texture::{ExternalTexture, Format};
 use euclid::{Point2D, Rect, Size2D};
-use gl::types::GLint;
+use gl::types::{GLint, GLuint};
 use glfw::{Action, Context, Key, OpenGlProfileHint, WindowEvent, WindowHint, WindowMode};
 use memmap::{Mmap, Protection};
 use pathfinder::batch::{BatchBuilder, GlyphRange};
@@ -32,7 +32,7 @@ const SHELF_HEIGHT: u32 = 32;
 
 fn main() {
     let mut glfw = glfw::init(glfw::LOG_ERRORS).unwrap();
-    glfw.window_hint(WindowHint::ContextVersion(3, 3));
+    glfw.window_hint(WindowHint::ContextVersion(4, 1));
     glfw.window_hint(WindowHint::OpenGlForwardCompat(true));
     glfw.window_hint(WindowHint::OpenGlProfile(OpenGlProfileHint::Core));
     let context = glfw.create_window(WIDTH, HEIGHT, "generate-atlas", WindowMode::Windowed);
@@ -40,6 +40,7 @@ fn main() {
     let (mut window, events) = context.expect("Couldn't create a window!");
     window.make_current();
     gl::load_with(|symbol| window.get_proc_address(symbol) as *const c_void);
+    let (device_pixel_width, device_pixel_height) = window.get_framebuffer_size();
 
     let instance = Instance::new().unwrap();
     let device = instance.create_device().unwrap();
@@ -48,7 +49,7 @@ fn main() {
     let rasterizer = Rasterizer::new(device, queue).unwrap();
 
     let mut glyph_buffer_builder = GlyphBufferBuilder::new();
-    let mut batch_builder = BatchBuilder::new(WIDTH, SHELF_HEIGHT);
+    let mut batch_builder = BatchBuilder::new(device_pixel_width as GLuint, SHELF_HEIGHT);
 
     let file = Mmap::open_path(env::args().nth(1).unwrap(), Protection::Read).unwrap();
     unsafe {
@@ -69,7 +70,7 @@ fn main() {
     let glyph_buffers = glyph_buffer_builder.finish().unwrap();
     let batch = batch_builder.finish(&glyph_buffer_builder).unwrap();
 
-    let atlas_size = Size2D::new(WIDTH, HEIGHT);
+    let atlas_size = Size2D::new(device_pixel_width as GLuint, device_pixel_height as GLuint);
     let coverage_buffer = CoverageBuffer::new(&rasterizer.device, &atlas_size).unwrap();
 
     let texture = rasterizer.device
@@ -98,6 +99,7 @@ fn main() {
     }
 
     unsafe {
+        gl::Viewport(0, 0, device_pixel_width, device_pixel_height);
         gl::ClearColor(1.0, 1.0, 1.0, 1.0);
         gl::Clear(gl::COLOR_BUFFER_BIT);
     }

resources/shaders/accum.cl

@@ -31,7 +31,7 @@ __kernel void accum(__write_only image2d_t gTexture,
         int2 coord = (int2)((int)column, (int)row);
         coverage += read_imagef(gCoverage, SAMPLER, coord).r;
 
-        uint gray = 255 - convert_uint(clamp(coverage, 0.0f, 1.0f) * 255.0f);
+        uint gray = convert_uint(clamp(coverage, 0.0f, 1.0f) * 255.0f);
         write_imageui(gTexture, coord + (int2)kAtlasRect.xy, (uint4)(gray, 255, 255, 255));
     }
 }

resources/shaders/draw.fs.glsl

@@ -28,7 +28,8 @@ out vec4 oFragColor;
 
 void main() {
     // Compute the X boundaries of this pixel.
-    float xMin = floor(gl_FragCoord.x), xMax = ceil(gl_FragCoord.x);
+    float xMin = floor(gl_FragCoord.x);
+    float xMax = xMin + 1.0f;
 
     // Compute the horizontal span that the line segment covers across this pixel.
     float dX = min(xMax, vP1.x) - max(xMin, vP0.x);

resources/shaders/draw.tcs.glsl

@@ -15,9 +15,6 @@
 
 layout(vertices = 1) out;
 
-// The size of the atlas in pixels.
-uniform uvec2 uAtlasSize;
-
 // The vertex ID, passed into this shader.
 flat in uint vVertexID[];
 
@@ -31,25 +28,26 @@ patch out vec2 vpP2;
 patch out float vpDirection;
 
 void main() {
-    vpP0 = gl_in[0].gl_Position.xy;
+    vec2 p0 = gl_in[0].gl_Position.xy;
-    vpP1 = gl_in[1].gl_Position.xy;
+    vec2 p1 = gl_in[1].gl_Position.xy;
-    vpP2 = gl_in[2].gl_Position.xy;
+    vec2 p2 = gl_in[2].gl_Position.xy;
 
     // Compute direction. Flip around if necessary so that p0 is to the left of p2.
-    if (vpP0.x < vpP2.x) {
+    float direction;
-        vpDirection = 1.0f;
+    if (p0.x < p2.x) {
+        direction = 1.0f;
     } else {
-        vpDirection = -1.0f;
+        direction = -1.0f;
-        vec2 tmp = vpP0;
+        vec2 tmp = p0;
-        vpP0 = vpP2;
+        p0 = p2;
-        vpP2 = tmp;
+        p2 = tmp;
     }
 
     // Divide into lines.
     float lineCount = 1.0f;
     if (vVertexID[1] > 0) {
         // Quadratic curve.
-        vec2 dev = vpP0 - 2.0f * vpP1 + vpP2;
+        vec2 dev = p0 - 2.0f * p1 + p2;
         float devSq = dot(dev, dev);
         if (devSq >= CURVE_THRESHOLD) {
             // Inverse square root is likely no slower and may be faster than regular square root
@@ -100,10 +98,19 @@ void main() {
     // so we're in the clear: the rasterizer will always discard the unshaded areas and render only
     // the shaded ones.
 
-    gl_TessLevelInner[0] = vpP0.x == vpP2.x ? 0.0f : lineCount * 2.0f - 1.0f;
+    float tessLevel = p0.x == p2.x ? 0.0f : (lineCount * 2.0f - 1.0f);
-    gl_TessLevelOuter[1] = gl_TessLevelOuter[3] = gl_TessLevelInner[0];
+    gl_TessLevelInner[0] = tessLevel;
+    gl_TessLevelInner[1] = 1.0f;
+    gl_TessLevelOuter[0] = 1.0f;
+    gl_TessLevelOuter[1] = tessLevel;
+    gl_TessLevelOuter[2] = 1.0f;
+    gl_TessLevelOuter[3] = tessLevel;
 
-    // Don't split vertically at all. We only tessellate horizontally.
+    // NB: These per-patch outputs must be assigned in this order, or Apple's compiler will
-    gl_TessLevelInner[1] = gl_TessLevelOuter[0] = gl_TessLevelOuter[2] = 1.0f;
+    // miscompile us.
+    vpP0 = p0;
+    vpP1 = p1;
+    vpP2 = p2;
+    vpDirection = direction;
 }
 

resources/shaders/draw.tes.glsl

@@ -51,7 +51,7 @@ void main() {
         float t0 = float(lineIndex + 0) / float(lineCount);
         float t1 = float(lineIndex + 1) / float(lineCount);
         vP0 = mix(mix(vpP0, vpP1, t0), mix(vpP1, vpP2, t0), t0);
-        vP1 = mix(mix(vpP0, vpP1, t1), mix(vpP1, vpP2, t0), t1);
+        vP1 = mix(mix(vpP0, vpP1, t1), mix(vpP1, vpP2, t1), t1);
     }
 
     // Compute Y extents and slope.

resources/shaders/draw.vs.glsl

@@ -10,29 +10,19 @@
 
 #version 410
 
-// FIXME(pcwalton): This should be higher. Dynamically query its maximum possible size, perhaps?
+#define MAX_GLYPHS  2048
-#define MAX_GLYPHS  256
+
+// Accessors to work around Apple driver bugs.
+#define GLYPH_DESCRIPTOR_UNITS_PER_EM(d)    (d).misc.x
+#define IMAGE_DESCRIPTOR_ATLAS_POS(d)       (d).xy
+#define IMAGE_DESCRIPTOR_POINT_SIZE(d)      (d).z
 
 // Information about the metrics of each glyph.
 layout(std140) struct GlyphDescriptor {
-    // The left/top/right/bottom offsets of the glyph from point (0, 0) in glyph space.
+    // The left/bottom/right/top offsets of the glyph from point (0, 0) in glyph space.
     ivec4 extents;
-    // The number of units per em in this glyph.
+    // x: Units per em.
-    uint unitsPerEm;
+    uvec4 misc;
-    // The index of the first point in the VBO.
-    uint startPoint;
-    // The index of the first element in the IBO.
-    uint startIndex;
-};
-
-// Information about the position of each glyph in the atlas.
-layout(std140) struct ImageDescriptor {
-    // The left/top/right/bottom positions of the glyph in the atlas.
-    uvec4 atlasRect;
-    // The font size in pixels.
-    float pointSize;
-    // The index of the glyph.
-    uint glyphIndex;
 };
 
 // The size of the atlas in pixels.
@@ -43,7 +33,7 @@ layout(std140) uniform ubGlyphDescriptors {
 };
 
 layout(std140) uniform ubImageDescriptors {
-    ImageDescriptor uImages[MAX_GLYPHS];
+    uvec4 uImages[MAX_GLYPHS];
 };
 
 // The position of each vertex in glyph space.
@@ -60,13 +50,13 @@ flat out uint vVertexID;
 void main() {
     vVertexID = gl_VertexID;
 
-    ImageDescriptor image = uImages[aGlyphIndex];
+    uvec4 image = uImages[aGlyphIndex];
     GlyphDescriptor glyph = uGlyphs[aGlyphIndex];
 
-    float emsPerUnit = 1.0f / float(glyph.unitsPerEm);
-
     vec2 glyphPos = vec2(aPosition.x - glyph.extents.x, glyph.extents.w - aPosition.y);
-    vec2 atlasPos = glyphPos * emsPerUnit * image.pointSize + vec2(image.atlasRect.xy);
+    float pointSize = float(IMAGE_DESCRIPTOR_POINT_SIZE(image)) / 65536.0f;
+    vec2 glyphPxPos = glyphPos * pointSize / GLYPH_DESCRIPTOR_UNITS_PER_EM(glyph);
+    vec2 atlasPos = glyphPxPos + vec2(IMAGE_DESCRIPTOR_ATLAS_POS(image));
 
     gl_Position = vec4(atlasPos, 0.0f, 1.0f);
 }

src/batch.rs

@@ -53,7 +53,7 @@ impl BatchBuilder {
         self.images[glyph_index as usize] = ImageDescriptor {
             atlas_x: atlas_origin.x,
             atlas_y: atlas_origin.y,
-            point_size: point_size,
+            point_size: (point_size * 65536.0) as u32,
             glyph_index: glyph_index,
         };
 
@@ -167,7 +167,7 @@ impl Iterator for GlyphRangeIter {
 pub struct ImageDescriptor {
     atlas_x: u32,
     atlas_y: u32,
-    point_size: f32,
+    point_size: u32,
     glyph_index: u32,
 }
 

src/coverage.rs

@@ -48,6 +48,7 @@ impl CoverageBuffer {
                                      gl::TEXTURE_RECTANGLE,
                                      gl_texture,
                                      0);
+            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
         }
 
         Ok(CoverageBuffer {

src/glyph_buffer.rs

@@ -61,9 +61,9 @@ impl GlyphBufferBuilder {
 
             if !point.first_point_in_contour && point.on_curve {
                 let indices = if last_point_on_curve {
-                    [point_index - 2, 0, point_index - 1]
+                    [point_index - 1, 0, point_index]
                 } else {
-                    [point_index - 3, point_index - 2, point_index - 1]
+                    [point_index - 2, point_index - 1, point_index]
                 };
                 self.indices.extend(indices.iter().cloned());
             }
@@ -132,7 +132,7 @@ pub struct GlyphBuffers {
 }
 
 #[repr(C)]
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub struct GlyphDescriptor {
     pub left: i32,
     pub bottom: i32,
@@ -154,7 +154,7 @@ impl GlyphDescriptor {
     }
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 #[repr(C)]
 pub struct Vertex {
     x: i16,

src/rasterizer.rs

@@ -39,16 +39,17 @@ pub struct Rasterizer {
     accum_program: Program,
     draw_vertex_array: GLuint,
     draw_position_attribute: GLint,
-    draw_image_index_attribute: GLint,
+    draw_glyph_index_attribute: GLint,
     draw_atlas_size_uniform: GLint,
     draw_glyph_descriptors_uniform: GLuint,
-    draw_image_info_uniform: GLuint,
+    draw_image_descriptors_uniform: GLuint,
 }
 
 impl Rasterizer {
     pub fn new(device: Device, queue: Queue) -> Result<Rasterizer, ()> {
-        let (draw_program, draw_position_attribute, draw_image_index_attribute);
+        let (draw_program, draw_position_attribute, draw_glyph_index_attribute);
-        let (draw_atlas_size_uniform, draw_glyph_descriptors_uniform, draw_image_info_uniform);
+        let (draw_glyph_descriptors_uniform, draw_image_descriptors_uniform);
+        let draw_atlas_size_uniform;
         let mut draw_vertex_array = 0;
         unsafe {
             let shaders = [
@@ -83,16 +84,17 @@ impl Rasterizer {
 
             draw_position_attribute =
                 gl::GetAttribLocation(draw_program, b"aPosition\0".as_ptr() as *const GLchar);
-            draw_image_index_attribute =
+            draw_glyph_index_attribute =
-                gl::GetAttribLocation(draw_program, b"aImageIndex\0".as_ptr() as *const GLchar);
+                gl::GetAttribLocation(draw_program, b"aGlyphIndex\0".as_ptr() as *const GLchar);
 
             draw_atlas_size_uniform =
                 gl::GetUniformLocation(draw_program, b"uAtlasSize\0".as_ptr() as *const GLchar);
             draw_glyph_descriptors_uniform =
                 gl::GetUniformBlockIndex(draw_program,
                                          b"ubGlyphDescriptors\0".as_ptr() as *const GLchar);
-            draw_image_info_uniform =
+            draw_image_descriptors_uniform =
-                gl::GetUniformBlockIndex(draw_program, b"ubImageInfo\0".as_ptr() as *const GLchar);
+                gl::GetUniformBlockIndex(draw_program,
+                                         b"ubImageDescriptors\0".as_ptr() as *const GLchar);
         }
 
         // FIXME(pcwalton): Don't panic if this fails to compile; just return an error.
@@ -105,10 +107,10 @@ impl Rasterizer {
             accum_program: accum_program,
             draw_vertex_array: draw_vertex_array,
             draw_position_attribute: draw_position_attribute,
-            draw_image_index_attribute: draw_image_index_attribute,
+            draw_glyph_index_attribute: draw_glyph_index_attribute,
             draw_atlas_size_uniform: draw_atlas_size_uniform,
             draw_glyph_descriptors_uniform: draw_glyph_descriptors_uniform,
-            draw_image_info_uniform: draw_image_info_uniform,
+            draw_image_descriptors_uniform: draw_image_descriptors_uniform,
         })
     }
 
@@ -121,8 +123,15 @@ impl Rasterizer {
                       texture: &Texture)
                       -> Result<Event, ()> {
         unsafe {
-            gl::UseProgram(self.draw_program);
+            gl::BindFramebuffer(gl::FRAMEBUFFER, coverage_buffer.framebuffer);
+            gl::Viewport(0, 0, atlas_rect.size.width as GLint, atlas_rect.size.height as GLint);
+
+            // TODO(pcwalton): Scissor to the atlas rect to clear faster?
+            gl::ClearColor(0.0, 0.0, 0.0, 1.0);
+            gl::Clear(gl::COLOR_BUFFER_BIT);
+
             gl::BindVertexArray(self.draw_vertex_array);
+            gl::UseProgram(self.draw_program);
 
             // Set up the buffer layout.
             gl::BindBuffer(gl::ARRAY_BUFFER, glyph_buffers.vertices);
@@ -131,20 +140,20 @@ impl Rasterizer {
                                      gl::SHORT,
                                      mem::size_of::<Vertex>() as GLint,
                                      0 as *const GLvoid);
-            gl::VertexAttribIPointer(self.draw_image_index_attribute as GLuint,
+            gl::VertexAttribIPointer(self.draw_glyph_index_attribute as GLuint,
                                      1,
                                      gl::UNSIGNED_SHORT,
                                      mem::size_of::<Vertex>() as GLint,
                                      mem::size_of::<(i16, i16)>() as *const GLvoid);
             gl::EnableVertexAttribArray(self.draw_position_attribute as GLuint);
-            gl::EnableVertexAttribArray(self.draw_image_index_attribute as GLuint);
+            gl::EnableVertexAttribArray(self.draw_glyph_index_attribute as GLuint);
 
             gl::BindBuffer(gl::ELEMENT_ARRAY_BUFFER, glyph_buffers.indices);
 
             gl::BindBufferBase(gl::UNIFORM_BUFFER, 1, glyph_buffers.descriptors);
             gl::BindBufferBase(gl::UNIFORM_BUFFER, 2, batch.images);
             gl::UniformBlockBinding(self.draw_program, self.draw_glyph_descriptors_uniform, 1);
-            gl::UniformBlockBinding(self.draw_program, self.draw_image_info_uniform, 2);
+            gl::UniformBlockBinding(self.draw_program, self.draw_image_descriptors_uniform, 2);
 
             gl::Uniform2ui(self.draw_atlas_size_uniform,
                            atlas_rect.size.width,
@@ -170,6 +179,16 @@ impl Rasterizer {
                                   gl::UNSIGNED_INT,
                                   batch.start_indices.as_ptr() as *const *const GLvoid,
                                   batch.counts.len() as GLsizei);
+
+            gl::Disable(gl::CULL_FACE);
+            gl::Disable(gl::BLEND);
+
+            gl::BindFramebuffer(gl::FRAMEBUFFER, 0);
+
+            // FIXME(pcwalton): We should have some better synchronization here if we're using
+            // OpenCL, but I don't know how to do that portably (i.e. on Mac…) Just using
+            // `glFlush()` seems to work in practice.
+            gl::Flush();
         }
 
         let atlas_rect_uniform = [