Refactor renderer functions out of main.rs

This moves the rendering logic to draw the grid, to draw strings, and to
draw the cursor into the renderere module. In addition to being an
organizational improvement, this also allowed for some optimizations
managing OpenGL state. Render times for a moderate screen of text
dropped from ~10ms to ~4ms.

src/main.rs

@@ -55,23 +55,12 @@ static INIT_LIST: &'static str = "abcdefghijklmnopqrstuvwxyz\
 
 type GlyphCache = HashMap<char, renderer::Glyph>;
 
-/// Render a string in a predefined location. Used for printing render time for profiling and
+struct TermProps {
-/// optimization.
+    cell_width: f32,
-fn render_string(s: &str,
+    sep_x: f32,
-                 renderer: &QuadRenderer,
+    cell_height: f32,
-                 glyph_cache: &GlyphCache,
+    sep_y: f32,
-                 cell_width: u32,
+    height: f32,
-                 color: &Rgb)
-{
-    let (mut x, mut y) = (200f32, 20f32);
-
-    for c in s.chars() {
-        if let Some(glyph) = glyph_cache.get(&c) {
-            renderer.render(glyph, x, y, color);
-        }
-
-        x += cell_width as f32 + 2f32;
-    }
 }
 
 fn main() {
@@ -135,7 +124,7 @@ fn main() {
         }
     });
 
-    let renderer = QuadRenderer::new(width, height);
+    let mut renderer = QuadRenderer::new(width, height);
     let mut terminal = Term::new(tty, grid);
     let mut meter = Meter::new();
 
@@ -191,43 +180,27 @@ fn main() {
         {
             let _sampler = meter.sampler();
 
+            let props = TermProps {
+                cell_width: cell_width as f32,
+                sep_x: sep_x as f32,
+                cell_height: cell_height as f32,
+                sep_y: sep_y as f32,
+                height: height as f32,
+            };
+
             // Draw the grid
-            let grid = terminal.grid();
+            renderer.render_grid(terminal.grid(), &glyph_cache, &props);
-            for i in 0..grid.rows() {
-                let row = &grid[i];
-                for j in 0..row.cols() {
-                    let cell = &row[j];
-                    if cell.c != ' ' {
-                        if let Some(glyph) = glyph_cache.get(&cell.c) {
-                            let y = (cell_height as f32 + sep_y as f32) * (i as f32);
-                            let x = (cell_width as f32 + sep_x as f32) * (j as f32);
-
-                            let y_inverted = (height as f32) - y - (cell_height as f32);
-
-                            renderer.render(glyph, x, y_inverted, &cell.fg);
-                        }
-                    }
-                }
-            }
 
             // Also draw the cursor
-            if let Some(glyph) = glyph_cache.get(&term::CURSOR_SHAPE) {
+            renderer.render_cursor(terminal.cursor(), &glyph_cache, &props);
-                let y = (cell_height as f32 + sep_y as f32) * (terminal.cursor_y() as f32);
-                let x = (cell_width as f32 + sep_x as f32) * (terminal.cursor_x() as f32);
-
-                let y_inverted = (height as f32) - y - (cell_height as f32);
-
-                renderer.render(glyph, x, y_inverted, &term::DEFAULT_FG);
-            }
         }
 
+        // Draw render timer
         let timing = format!("{:.3} usec", meter.average());
         let color = Rgb { r: 0xd5, g: 0x4e, b: 0x53 };
-        render_string(&timing[..], &renderer, &glyph_cache, cell_width, &color);
+        renderer.render_string(&timing[..], &glyph_cache, cell_width, &color);
 
         window.swap_buffers().unwrap();
-
-        // ::std::thread::sleep(::std::time::Duration::from_millis(17));
     }
 }
 

src/renderer/mod.rs

@@ -2,16 +2,16 @@ use std::ffi::CString;
 use std::mem::size_of;
 use std::ptr;
 
-use gl;
+use cgmath::{self, Matrix};
-use cgmath;
-
 use euclid::{Rect, Size2D, Point2D};
-
 use gl::types::*;
-
+use gl;
-use cgmath::Matrix;
 
 use text::RasterizedGlyph;
+use grid::Grid;
+use term;
+
+use super::{Rgb, TermProps, GlyphCache};
 
 static TEXT_SHADER_V: &'static str = include_str!("../../res/text.v.glsl");
 static TEXT_SHADER_F: &'static str = include_str!("../../res/text.f.glsl");
@@ -21,6 +21,7 @@ pub struct QuadRenderer {
     vao: GLuint,
     vbo: GLuint,
     ebo: GLuint,
+    active_color: Rgb,
 }
 
 #[allow(dead_code)]
@@ -32,7 +33,6 @@ pub struct PackedVertex {
     v: f32,
 }
 
-use super::Rgb;
 
 impl QuadRenderer {
     // TODO should probably hand this a transform instead of width/height
@@ -91,14 +91,101 @@ impl QuadRenderer {
             vao: vao,
             vbo: vbo,
             ebo: ebo,
+            active_color: Rgb { r: 0, g: 0, b: 0 },
         }
     }
 
-    pub fn render(&self, glyph: &Glyph, x: f32, y: f32, color: &Rgb) {
+    /// Render a string in a predefined location. Used for printing render time for profiling and
-        self.program.activate();
+    /// optimization.
+    pub fn render_string(&mut self,
+                     s: &str,
+                     glyph_cache: &GlyphCache,
+                     cell_width: u32,
+                     color: &Rgb)
+    {
+        self.prepare_render();
+
+        let (mut x, mut y) = (200f32, 20f32);
+
+        for c in s.chars() {
+            if let Some(glyph) = glyph_cache.get(&c) {
+                self.render(glyph, x, y, color);
+            }
+
+            x += cell_width as f32 + 2f32;
+        }
+
+        self.finish_render();
+    }
+
+    pub fn render_cursor(&mut self,
+                         cursor: term::Cursor,
+                         glyph_cache: &GlyphCache,
+                         props: &TermProps)
+    {
+        self.prepare_render();
+        if let Some(glyph) = glyph_cache.get(&term::CURSOR_SHAPE) {
+            let y = (props.cell_height + props.sep_y) * (cursor.y as f32);
+            let x = (props.cell_width + props.sep_x) * (cursor.x as f32);
+
+            let y_inverted = props.height - y - props.cell_height;
+
+            self.render(glyph, x, y_inverted, &term::DEFAULT_FG);
+        }
+
+        self.finish_render();
+    }
+
+    pub fn render_grid(&mut self, grid: &Grid, glyph_cache: &GlyphCache, props: &TermProps) {
+        self.prepare_render();
+        for i in 0..grid.rows() {
+            let row = &grid[i];
+            for j in 0..row.cols() {
+                let cell = &row[j];
+                if cell.c != ' ' {
+                    if let Some(glyph) = glyph_cache.get(&cell.c) {
+                        let y = (props.cell_height + props.sep_y) * (i as f32);
+                        let x = (props.cell_width + props.sep_x) * (j as f32);
+
+                        let y_inverted = (props.height) - y - (props.cell_height);
+
+                        self.render(glyph, x, y_inverted, &cell.fg);
+                    }
+                }
+            }
+        }
+        self.finish_render();
+    }
+
+    fn prepare_render(&self) {
         unsafe {
-            // set color
+            self.program.activate();
-            gl::Uniform3i(self.program.u_color, color.r as i32, color.g as i32, color.b as i32);
+
+            gl::BindVertexArray(self.vao);
+            gl::BindBuffer(gl::ARRAY_BUFFER, self.vbo);
+            gl::BindBuffer(gl::ELEMENT_ARRAY_BUFFER, self.ebo);
+        }
+    }
+
+    fn finish_render(&self) {
+        unsafe {
+            gl::BindBuffer(gl::ELEMENT_ARRAY_BUFFER, 0);
+            gl::BindBuffer(gl::ARRAY_BUFFER, 0);
+            gl::BindVertexArray(0);
+
+            self.program.deactivate();
+        }
+    }
+
+    fn render(&mut self, glyph: &Glyph, x: f32, y: f32, color: &Rgb) {
+        if &self.active_color != color {
+            unsafe {
+                gl::Uniform3i(self.program.u_color,
+                              color.r as i32,
+                              color.g as i32,
+                              color.b as i32);
+            }
+            self.active_color = color.to_owned();
         }
 
         let rect = get_rect(glyph, x, y);
@@ -113,24 +200,16 @@ impl QuadRenderer {
 
         unsafe {
             bind_mask_texture(glyph.tex_id);
-            gl::BindVertexArray(self.vao);
-
-            gl::BindBuffer(gl::ARRAY_BUFFER, self.vbo);
             gl::BufferSubData(
                 gl::ARRAY_BUFFER,
                 0,
                 (packed.len() * size_of::<PackedVertex>()) as isize,
                 packed.as_ptr() as *const _
             );
-            gl::BindBuffer(gl::ARRAY_BUFFER, 0);
-            gl::BindBuffer(gl::ELEMENT_ARRAY_BUFFER, self.ebo);
 
             gl::DrawElements(gl::TRIANGLES, 6, gl::UNSIGNED_INT, ptr::null());
-            gl::BindVertexArray(0);
             gl::BindTexture(gl::TEXTURE_2D, 0);
         }
-
-        self.program.deactivate();
     }
 }
 
@@ -195,6 +274,11 @@ impl ShaderProgram {
         assert!(color != gl::INVALID_VALUE as i32);
         assert!(color != gl::INVALID_OPERATION as i32);
 
+        // Initialize to known color (black)
+        unsafe {
+            gl::Uniform3i(color, 0, 0, 0);
+        }
+
         let shader = ShaderProgram {
             id: program,
             u_projection: projection,

src/term.rs

@@ -142,6 +142,11 @@ impl Term {
         self.cursor.y
     }
 
+    #[inline]
+    pub fn cursor(&self) -> Cursor {
+        self.cursor
+    }
+
     /// Set character in current cursor position
     fn set_char(&mut self, c: char) {
         let cell = &mut self.grid[self.cursor];