text.rs

   1 use cgmath::conv::array4x4;
   2 use cgmath::{Matrix4, Vector3};
   3 use glium;
   4 use glium::{Display, Program, Surface, implement_vertex, texture, uniform};
   5 use std;
   6
   7 fn gamma<T>(x: T) -> f32
   8 where
   9     f32: From<T>,
  10     T: Copy,
  11 {
  12     ((f32::from(x)) / 255.).powf(2.2)
  13 }
  14
  15 fn srgb<T>(c: [T; 3]) -> [f32; 4]
  16 where
  17     f32: From<T>,
  18     T: Copy,
  19 {
  20     [gamma(c[0]), gamma(c[1]), gamma(c[2]), 0.0]
  21 }
  22
  23 #[cfg(feature = "image")]
  24 fn c64_font() -> (u32, u32, Vec<u8>) {
  25     let image = image::load_from_memory_with_format(
  26         &include_bytes!("textures/c64-font.png")[..],
  27         image::PNG,
  28     ).unwrap()
  29         .to_luma();
  30     let (w, h) = image.dimensions();
  31     (w, h, image.into_raw())
  32 }
  33
  34 #[cfg(not(feature = "image"))]
  35 fn c64_font() -> (u32, u32, Vec<u8>) {
  36     let pixels = &include_bytes!("textures/c64-font.gray")[..];
  37     (128, 128, Vec::from(pixels))
  38 }
  39
  40 pub fn text_program(display: &Display) -> Program {
  41     //load_program(display, "shaders/text.vert", "shaders/text.frag");
  42     let vertex_shader_src = include_str!("shaders/text.vert");
  43     let fragment_shader_src = include_str!("shaders/text.frag");
  44     Program::from_source(display, vertex_shader_src, fragment_shader_src, None).unwrap()
  45 }
  46
  47 #[derive(Copy, Clone)]
  48 struct Vertex {
  49     position: [f32; 2],
  50     tex_coords: [f32; 2],
  51 }
  52 implement_vertex!(Vertex, position, tex_coords);
  53
  54 pub struct Text<'a> {
  55     tex: texture::Texture2d,
  56     vertex_buffer: glium::VertexBuffer<Vertex>,
  57     index_buffer: glium::IndexBuffer<u16>,
  58     program: glium::Program,
  59     params: glium::DrawParameters<'a>,
  60     pub model: Matrix4<f32>,
  61     pub character: char,
  62 }
  63
  64 impl<'a> Text<'a> {
  65     pub fn new(display: &Display, character: char) -> Text<'_> {
  66         let (w, h, pixels) = c64_font();
  67         let image = glium::texture::RawImage2d {
  68             data: std::borrow::Cow::from(pixels),
  69             width: w,
  70             height: h,
  71             format: glium::texture::ClientFormat::U8,
  72         };
  73         let tex = glium::texture::Texture2d::with_format(
  74             display,
  75             image,
  76             glium::texture::UncompressedFloatFormat::U8,
  77             glium::texture::MipmapsOption::NoMipmap,
  78         ).unwrap();
  79
  80         // building the vertex buffer, which contains all the vertices that we will draw
  81         let vertex_buffer = {
  82             glium::VertexBuffer::new(
  83                 display,
  84                 &[
  85                     Vertex {
  86                         position: [-0.5, -0.5],
  87                         tex_coords: [0.0, 1.0],
  88                     },
  89                     Vertex {
  90                         position: [-0.5, 0.5],
  91                         tex_coords: [0.0, 0.0],
  92                     },
  93                     Vertex {
  94                         position: [0.5, 0.5],
  95                         tex_coords: [1.0, 0.0],
  96                     },
  97                     Vertex {
  98                         position: [0.5, -0.5],
  99                         tex_coords: [1.0, 1.0],
 100                     },
 101                 ],
 102             ).unwrap()
 103         };
 104
 105         let index_buffer = glium::IndexBuffer::new(
 106             display,
 107             glium::index::PrimitiveType::TriangleStrip,
 108             &[1 as u16, 2, 0, 3],
 109         ).unwrap();
 110
 111         let params = glium::DrawParameters {
 112             depth: glium::Depth {
 113                 test: glium::draw_parameters::DepthTest::IfLess,
 114                 write: true,
 115                 ..Default::default()
 116             },
 117             multisampling: true,
 118             ..Default::default()
 119         };
 120
 121         Text {
 122             tex: tex,
 123             vertex_buffer: vertex_buffer,
 124             index_buffer: index_buffer,
 125             program: text_program(display),
 126             params: params,
 127             model: Matrix4::from_translation(Vector3::unit_z() * (-1.0)),
 128             character: character,
 129         }
 130     }
 131
 132     pub fn draw(&self, frame: &mut glium::Frame, perspview: &[[f32; 4]; 4]) {
 133         let uniforms =
 134             uniform! {
 135             model: array4x4(self.model),
 136             perspview: *perspview,
 137             tex: self.tex.sampled()
 138                 .magnify_filter(glium::uniforms::MagnifySamplerFilter::Nearest),
 139             index: self.character as i32,
 140             // RGB values from http://unusedino.de/ec64/technical/misc/vic656x/colors/
 141             bgcolor: srgb([ 64,  50, 133u8]),  //  6 - blue
 142             fgcolor: srgb([120, 106, 189u8]),  // 14 - light blue
 143         };
 144         frame
 145             .draw(
 146                 &self.vertex_buffer,
 147                 &self.index_buffer,
 148                 &self.program,
 149                 &uniforms,
 150                 &self.params,
 151             )
 152             .unwrap();
 153     }
 154 }