Simplify text shader

5 files changed, 60 insertions, 127 deletions

diff --git a/Cargo.lock b/Cargo.lock
index cc7bddaf..91d29e3f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -35,7 +35,6 @@ dependencies = [
  "arraydeque 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "base64 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "cgmath 0.17.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "copypasta 0.0.1",
  "dirs 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -284,16 +283,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "cgmath"
-version = "0.17.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "approx 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
-[[package]]
 name = "clang-sys"
 version = "0.22.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2749,7 +2738,6 @@ dependencies = [
 "checksum cexpr 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "42aac45e9567d97474a834efdee3081b3c942b2205be932092f53354ce503d6c"
 "checksum cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "082bb9b28e00d3c9d39cc03e64ce4cea0f1bb9b3fde493f0cbc008472d22bdf4"
 "checksum cgl 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "55e7ec0b74fe5897894cbc207092c577e87c52f8a59e8ca8d97ef37551f60a49"
-"checksum cgmath 0.17.0 (registry+https://github.com/rust-lang/crates.io-index)" = "283944cdecc44bf0b8dd010ec9af888d3b4f142844fdbe026c20ef68148d6fe7"
 "checksum clang-sys 0.22.0 (registry+https://github.com/rust-lang/crates.io-index)" = "939a1a34310b120d26eba35c29475933128b0ec58e24b43327f8dbe6036fc538"
 "checksum clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b957d88f4b6a63b9d70d5f454ac8011819c6efa7727858f458ab71c756ce2d3e"
 "checksum clipboard 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "b9b4623b47d8637fc9d47564583d4cc01eb8c8e34e26b2bf348bf4b036acb657"
diff --git a/Cargo.toml b/Cargo.toml
index cac5ec4d..7935d346 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,7 +23,6 @@ name = "alacritty"
 
 [dependencies]
 libc = "0.2"
-cgmath = "0.17"
 notify = "4"
 bitflags = "1"
 font = { path = "./font" }
diff --git a/res/text.f.glsl b/res/text.f.glsl
index 532cf929..70ad3d19 100644
--- a/res/text.f.glsl
+++ b/res/text.f.glsl
@@ -13,19 +13,18 @@
 // limitations under the License.
 #version 330 core
 in vec2 TexCoords;
-in vec3 fg;
-in vec4 bg;
-flat in int background;
+flat in vec3 fg;
+flat in vec4 bg;
+uniform int backgroundPass;
 
 layout(location = 0, index = 0) out vec4 color;
 layout(location = 0, index = 1) out vec4 alphaMask;
 
-uniform float bgOpacity;
 uniform sampler2D mask;
 
 void main()
 {
-    if (background != 0) {
+    if (backgroundPass != 0) {
         if (bg.a == 0.0)
             discard;
 
diff --git a/res/text.v.glsl b/res/text.v.glsl
index 32aee5ac..369e7c7e 100644
--- a/res/text.v.glsl
+++ b/res/text.v.glsl
@@ -12,67 +12,63 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 #version 330 core
-layout (location = 0) in vec2 position;
-
 // Cell properties
-layout (location = 1) in vec2 gridCoords;
+layout (location = 0) in vec2 gridCoords;
 
 // glyph properties
-layout (location = 2) in vec4 glyph;
+layout (location = 1) in vec4 glyph;
 
 // uv mapping
-layout (location = 3) in vec4 uv;
+layout (location = 2) in vec4 uv;
 
 // text fg color
-layout (location = 4) in vec3 textColor;
+layout (location = 3) in vec3 textColor;
 
 // Background color
-layout (location = 5) in vec4 backgroundColor;
+layout (location = 4) in vec4 backgroundColor;
 
 out vec2 TexCoords;
-out vec3 fg;
-out vec4 bg;
+flat out vec3 fg;
+flat out vec4 bg;
 
 // Terminal properties
-uniform vec2 termDim;
 uniform vec2 cellDim;
+uniform vec4 projection;
 
 uniform int backgroundPass;
 
-// Orthographic projection
-uniform mat4 projection;
-flat out int background;
 
 void main()
 {
-    vec2 glyphOffset = glyph.xy;
-    vec2 glyphSize = glyph.zw;
-    vec2 uvOffset = uv.xy;
-    vec2 uvSize = uv.zw;
+    vec2 projectionOffset = projection.xy;
+    vec2 projectionScale = projection.zw;
 
-    // Position of cell from top-left
-    vec2 cellPosition = (cellDim) * gridCoords;
+    // Compute vertex corner position
+    vec2 position;
+    position.x = (gl_VertexID == 0 || gl_VertexID == 1) ? 1. : 0;
+    position.y = (gl_VertexID == 0 || gl_VertexID == 3) ? 0. : 1;
 
-    // Invert Y since framebuffer origin is bottom-left
-    cellPosition.y = termDim.y - cellPosition.y - cellDim.y;
+    // Position of cell from top-left
+    vec2 cellPosition = cellDim * gridCoords;
 
     if (backgroundPass != 0) {
-        cellPosition.y = cellPosition.y;
-        vec2 finalPosition = cellDim * position + cellPosition;
-        gl_Position = projection * vec4(finalPosition.xy, 0.0, 1.0);
+        vec2 finalPosition = cellPosition + cellDim * position;
+        gl_Position = vec4(projectionOffset + projectionScale * finalPosition, 0.0, 1.0);
+
         TexCoords = vec2(0, 0);
     } else {
-        // Glyphs are offset within their cell; account for y-flip
-        vec2 cellOffset = vec2(glyphOffset.x, glyphOffset.y - glyphSize.y);
+        vec2 glyphSize = glyph.zw;
+        vec2 glyphOffset = glyph.xy;
+        glyphOffset.y = cellDim.y - glyphOffset.y;
 
-        // position coordinates are normalized on [0, 1]
-        vec2 finalPosition = glyphSize * position + cellPosition + cellOffset;
+        vec2 finalPosition = cellPosition + glyphSize * position + glyphOffset;
+        gl_Position = vec4(projectionOffset + projectionScale * finalPosition, 0.0, 1.0);
 
-        gl_Position = projection * vec4(finalPosition.xy, 0.0, 1.0);
-        TexCoords = uvOffset + vec2(position.x, 1 - position.y) * uvSize;
+        vec2 uvOffset = uv.xy;
+        vec2 uvSize = uv.zw;
+        TexCoords = uvOffset + position * uvSize;
     }
 
-    background = backgroundPass;
     bg = vec4(backgroundColor.rgb / 255.0, backgroundColor.a);
     fg = textColor / vec3(255.0, 255.0, 255.0);
 }
diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index 1446fe3c..e96d35a5 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -21,7 +21,6 @@ use std::ptr;
 use std::sync::mpsc;
 use std::time::Duration;
 
-use cgmath;
 use fnv::FnvHasher;
 use glutin::dpi::PhysicalSize;
 use font::{self, FontDesc, FontKey, GlyphKey, Rasterize, RasterizedGlyph, Rasterizer};
@@ -111,12 +110,9 @@ pub struct TextShaderProgram {
     // Program id
     id: GLuint,
 
-    /// projection matrix uniform
+    /// projection scale and offset uniform
     u_projection: GLint,
 
-    /// Terminal dimensions (pixels)
-    u_term_dim: GLint,
-
     /// Cell dimensions (pixels)
     u_cell_dim: GLint,
 
@@ -486,13 +482,11 @@ const BATCH_MAX: usize = 0x1_0000;
 const ATLAS_SIZE: i32 = 1024;
 
 impl QuadRenderer {
-    // TODO should probably hand this a transform instead of width/height
     pub fn new(size: PhysicalSize) -> Result<QuadRenderer, Error> {
         let program = TextShaderProgram::new(size)?;
         let rect_program = RectShaderProgram::new()?;
 
         let mut vao: GLuint = 0;
-        let mut vbo: GLuint = 0;
         let mut ebo: GLuint = 0;
 
         let mut vbo_instance: GLuint = 0;
@@ -506,42 +500,14 @@ impl QuadRenderer {
             gl::BlendFunc(gl::SRC1_COLOR, gl::ONE_MINUS_SRC1_COLOR);
             gl::Enable(gl::MULTISAMPLE);
 
+            // Disable depth mask, as the renderer never uses depth tests
+            gl::DepthMask(gl::FALSE);
+
             gl::GenVertexArrays(1, &mut vao);
-            gl::GenBuffers(1, &mut vbo);
             gl::GenBuffers(1, &mut ebo);
             gl::GenBuffers(1, &mut vbo_instance);
             gl::BindVertexArray(vao);
 
-            // ----------------------------
-            // setup vertex position buffer
-            // ----------------------------
-            // Top right, Bottom right, Bottom left, Top left
-            let vertices = [
-                PackedVertex { x: 1.0, y: 1.0 },
-                PackedVertex { x: 1.0, y: 0.0 },
-                PackedVertex { x: 0.0, y: 0.0 },
-                PackedVertex { x: 0.0, y: 1.0 },
-            ];
-
-            gl::BindBuffer(gl::ARRAY_BUFFER, vbo);
-
-            gl::VertexAttribPointer(
-                0,
-                2,
-                gl::FLOAT,
-                gl::FALSE,
-                size_of::<PackedVertex>() as i32,
-                ptr::null(),
-            );
-            gl::EnableVertexAttribArray(0);
-
-            gl::BufferData(
-                gl::ARRAY_BUFFER,
-                (size_of::<PackedVertex>() * vertices.len()) as GLsizeiptr,
-                vertices.as_ptr() as *const _,
-                gl::STATIC_DRAW,
-            );
-
             // ---------------------
             // Set up element buffer
             // ---------------------
@@ -567,59 +533,59 @@ impl QuadRenderer {
             );
             // coords
             gl::VertexAttribPointer(
-                1,
+                0,
                 2,
                 gl::FLOAT,
                 gl::FALSE,
                 size_of::<InstanceData>() as i32,
                 ptr::null(),
             );
-            gl::EnableVertexAttribArray(1);
-            gl::VertexAttribDivisor(1, 1);
+            gl::EnableVertexAttribArray(0);
+            gl::VertexAttribDivisor(0, 1);
             // glyphoffset
             gl::VertexAttribPointer(
-                2,
+                1,
                 4,
                 gl::FLOAT,
                 gl::FALSE,
                 size_of::<InstanceData>() as i32,
                 (2 * size_of::<f32>()) as *const _,
             );
-            gl::EnableVertexAttribArray(2);
-            gl::VertexAttribDivisor(2, 1);
+            gl::EnableVertexAttribArray(1);
+            gl::VertexAttribDivisor(1, 1);
             // uv
             gl::VertexAttribPointer(
-                3,
+                2,
                 4,
                 gl::FLOAT,
                 gl::FALSE,
                 size_of::<InstanceData>() as i32,
                 (6 * size_of::<f32>()) as *const _,
             );
-            gl::EnableVertexAttribArray(3);
-            gl::VertexAttribDivisor(3, 1);
+            gl::EnableVertexAttribArray(2);
+            gl::VertexAttribDivisor(2, 1);
             // color
             gl::VertexAttribPointer(
-                4,
+                3,
                 3,
                 gl::FLOAT,
                 gl::FALSE,
                 size_of::<InstanceData>() as i32,
                 (10 * size_of::<f32>()) as *const _,
             );
-            gl::EnableVertexAttribArray(4);
-            gl::VertexAttribDivisor(4, 1);
+            gl::EnableVertexAttribArray(3);
+            gl::VertexAttribDivisor(3, 1);
             // color
             gl::VertexAttribPointer(
-                5,
+                4,
                 4,
                 gl::FLOAT,
                 gl::FALSE,
                 size_of::<InstanceData>() as i32,
                 (13 * size_of::<f32>()) as *const _,
             );
-            gl::EnableVertexAttribArray(5);
-            gl::VertexAttribDivisor(5, 1);
+            gl::EnableVertexAttribArray(4);
+            gl::VertexAttribDivisor(4, 1);
 
             // Rectangle setup
             gl::GenVertexArrays(1, &mut rect_vao);
@@ -1174,21 +1140,19 @@ impl TextShaderProgram {
         }
 
         // get uniform locations
-        let (projection, term_dim, cell_dim, background) = unsafe {
+        let (projection, cell_dim, background) = unsafe {
             (
                 gl::GetUniformLocation(program, cptr!(b"projection\0")),
-                gl::GetUniformLocation(program, cptr!(b"termDim\0")),
                 gl::GetUniformLocation(program, cptr!(b"cellDim\0")),
                 gl::GetUniformLocation(program, cptr!(b"backgroundPass\0")),
             )
         };
 
-        assert_uniform_valid!(projection, term_dim, cell_dim);
+        assert_uniform_valid!(projection, cell_dim, background);
 
         let shader = TextShaderProgram {
             id: program,
             u_projection: projection,
-            u_term_dim: term_dim,
             u_cell_dim: cell_dim,
             u_background: background,
         };
@@ -1208,36 +1172,23 @@ impl TextShaderProgram {
             return;
         }
 
-        // set projection uniform
-        //
-        // NB Not sure why padding change only requires changing the vertical
-        //    translation in the projection, but this makes everything work
-        //    correctly.
-        let ortho = cgmath::ortho(
-            0.,
-            width - (2. * padding_x),
-            2. * padding_y,
-            height,
-            -1.,
-            1.,
-        );
-        let projection: [[f32; 4]; 4] = ortho.into();
+        // Compute scale and offset factors, from pixel to ndc space. Y is inverted
+        //   [0, width - 2 * padding_x] to [-1, 1]
+        //   [height - 2 * padding_y, 0] to [-1, 1]
+        let scale_x = 2. / (width - 2. * padding_x);
+        let scale_y = -2. / (height - 2. * padding_y);
+        let offset_x = -1.;
+        let offset_y = 1.;
 
         info!("Width: {}, Height: {}", width, height);
 
         unsafe {
-            gl::UniformMatrix4fv(
-                self.u_projection,
-                1,
-                gl::FALSE,
-                projection.as_ptr() as *const _,
-            );
+            gl::Uniform4f(self.u_projection, offset_x, offset_y, scale_x, scale_y);
         }
     }
 
     fn set_term_uniforms(&self, props: &term::SizeInfo) {
         unsafe {
-            gl::Uniform2f(self.u_term_dim, props.width, props.height);
             gl::Uniform2f(self.u_cell_dim, props.cell_width, props.cell_height);
         }
     }