1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

//! A batched line renderer.

use crate::context::Context;
use crate::planar_camera::PlanarCamera;
use crate::resource::{AllocationType, BufferType, Effect, GPUVec, ShaderAttribute, ShaderUniform};
use na::{Matrix3, Point2, Point3};

#[path = "error.rs"]
mod error;

/// Structure which manages the display of short-living lines.
pub struct PlanarLineRenderer {
    shader: Effect,
    pos: ShaderAttribute<Point2<f32>>,
    color: ShaderAttribute<Point3<f32>>,
    view: ShaderUniform<Matrix3<f32>>,
    proj: ShaderUniform<Matrix3<f32>>,
    colors: GPUVec<Point3<f32>>,
    lines: GPUVec<Point2<f32>>,
    line_width: f32,
}

impl PlanarLineRenderer {
    /// Creates a new lines manager.
    pub fn new() -> PlanarLineRenderer {
        let mut shader = Effect::new_from_str(LINES_VERTEX_SRC, LINES_FRAGMENT_SRC);

        shader.use_program();

        PlanarLineRenderer {
            lines: GPUVec::new(Vec::new(), BufferType::Array, AllocationType::StreamDraw),
            colors: GPUVec::new(Vec::new(), BufferType::Array, AllocationType::StreamDraw),
            pos: shader
                .get_attrib::<Point2<f32>>("position")
                .expect("Failed to get shader attribute."),
            color: shader
                .get_attrib::<Point3<f32>>("color")
                .expect("Failed to get shader attribute."),
            view: shader
                .get_uniform::<Matrix3<f32>>("view")
                .expect("Failed to get shader uniform."),
            proj: shader
                .get_uniform::<Matrix3<f32>>("proj")
                .expect("Failed to get shader uniform."),
            shader,
            line_width: 1.0,
        }
    }

    /// Indicates whether some lines have to be drawn.
    pub fn needs_rendering(&self) -> bool {
        self.lines.len() != 0
    }

    /// Adds a line to be drawn during the next frame. Lines are not persistent between frames.
    /// This method must be called for each line to draw, and at each update loop iteration.
    pub fn draw_line(&mut self, a: Point2<f32>, b: Point2<f32>, color: Point3<f32>) {
        for lines in self.lines.data_mut().iter_mut() {
            lines.push(a);
            lines.push(b);
        }
        for colors in self.colors.data_mut().iter_mut() {
            colors.push(color);
            colors.push(color);
        }
    }

    /// Actually draws the lines.
    pub fn render(&mut self, camera: &mut dyn PlanarCamera) {
        if self.lines.len() == 0 {
            return;
        }

        self.shader.use_program();
        self.pos.enable();
        self.color.enable();

        camera.upload(&mut self.proj, &mut self.view);

        self.color.bind_sub_buffer(&mut self.colors, 0, 0);
        self.pos.bind_sub_buffer(&mut self.lines, 0, 0);

        let ctxt = Context::get();
        verify!(ctxt.draw_arrays(Context::LINES, 0, self.lines.len() as i32));
        verify!(ctxt.line_width(self.line_width));

        self.pos.disable();
        self.color.disable();

        for lines in self.lines.data_mut().iter_mut() {
            lines.clear()
        }

        for colors in self.colors.data_mut().iter_mut() {
            colors.clear()
        }
    }

    /// Sets the line width for the rendered lines.
    pub fn set_line_width(&mut self, line_width: f32) {
        self.line_width = line_width.max(f32::EPSILON /* Gl will usually round this to 1 pixel */);
    }
}

/// Vertex shader used by the material to display line.
static LINES_VERTEX_SRC: &str = A_VERY_LONG_STRING;
/// Fragment shader used by the material to display line.
static LINES_FRAGMENT_SRC: &str = ANOTHER_VERY_LONG_STRING;

const A_VERY_LONG_STRING: &str = "#version 100
    attribute vec2 position;
    attribute vec3 color;
    varying   vec3 vColor;
    uniform   mat3 proj;
    uniform   mat3 view;

    void main() {
        vec3 projected_pos = proj * view * vec3(position, 1.0);
        projected_pos.z = 0.0;

        gl_Position = vec4(projected_pos, 1.0);
        vColor = color;
    }";

const ANOTHER_VERY_LONG_STRING: &str = "#version 100
#ifdef GL_FRAGMENT_PRECISION_HIGH
   precision highp float;
#else
   precision mediump float;
#endif

    varying vec3 vColor;
    void main() {
        gl_FragColor = vec4(vColor, 1.0);
    }";