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
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191

//! 2D shapes rendering.

use crate::{color::Color, get_context};

use crate::quad_gl::{DrawMode, Vertex};
use glam::{vec2, Vec2};

/// Draws a solid triangle between points `v1`, `v2`, and `v3` with a given `color`.
pub fn draw_triangle(v1: Vec2, v2: Vec2, v3: Vec2, color: Color) {
    let context = get_context();

    let mut vertices = Vec::<Vertex>::with_capacity(3);

    vertices.push(Vertex::new(v1.x, v1.y, 0., 0., 0., color));
    vertices.push(Vertex::new(v2.x, v2.y, 0., 0., 0., color));
    vertices.push(Vertex::new(v3.x, v3.y, 0., 0., 0., color));
    let indices: [u16; 3] = [0, 1, 2];

    context.gl.texture(None);
    context.gl.draw_mode(DrawMode::Triangles);
    context.gl.geometry(&vertices, &indices);
}

/// Draws a triangle outline between points `v1`, `v2`, and `v3` with a given line `thickness` and `color`.
pub fn draw_triangle_lines(v1: Vec2, v2: Vec2, v3: Vec2, thickness: f32, color: Color) {
    draw_line(v1.x, v1.y, v2.x, v2.y, thickness, color);
    draw_line(v2.x, v2.y, v3.x, v3.y, thickness, color);
    draw_line(v3.x, v3.y, v1.x, v1.y, thickness, color);
}

/// Draws a solid rectangle with its top-left corner at `[x, y]` with size `[w, h]` (width going to
/// the right, height going down), with a given `color`.
pub fn draw_rectangle(x: f32, y: f32, w: f32, h: f32, color: Color) {
    let context = get_context();

    #[rustfmt::skip]
    let vertices = [
        Vertex::new(x    , y    , 0., 0.0, 0.0, color),
        Vertex::new(x + w, y    , 0., 1.0, 0.0, color),
        Vertex::new(x + w, y + h, 0., 1.0, 1.0, color),
        Vertex::new(x    , y + h, 0., 0.0, 1.0, color),
    ];
    let indices: [u16; 6] = [0, 1, 2, 0, 2, 3];

    context.gl.texture(None);
    context.gl.draw_mode(DrawMode::Triangles);
    context.gl.geometry(&vertices, &indices);
}

/// Draws a rectangle outline with its top-left corner at `[x, y]` with size `[w, h]` (width going to
/// the right, height going down), with a given line `thickness` and `color`.
pub fn draw_rectangle_lines(x: f32, y: f32, w: f32, h: f32, thickness: f32, color: Color) {
    let context = get_context();
    let t = thickness / 2.;

    #[rustfmt::skip]
    let vertices = [
        Vertex::new(x    , y    , 0., 0.0, 1.0, color),
        Vertex::new(x + w, y    , 0., 1.0, 0.0, color),
        Vertex::new(x + w, y + h, 0., 1.0, 1.0, color),
        Vertex::new(x    , y + h, 0., 0.0, 0.0, color),
        //inner rectangle
        Vertex::new(x + t    , y + t    , 0., 0.0, 0.0, color),
        Vertex::new(x + w - t, y + t    , 0., 0.0, 0.0, color),
        Vertex::new(x + w - t, y + h - t, 0., 0.0, 0.0, color),
        Vertex::new(x + t    , y + h - t, 0., 0.0, 0.0, color),
    ];
    let indices: [u16; 24] = [
        0, 1, 4, 1, 4, 5, 1, 5, 6, 1, 2, 6, 3, 7, 2, 2, 7, 6, 0, 4, 3, 3, 4, 7,
    ];

    context.gl.texture(None);
    context.gl.draw_mode(DrawMode::Triangles);
    context.gl.geometry(&vertices, &indices);
}

/// Draws an outlined solid hexagon centered at `[x, y]` with a radius `size`, outline thickness
/// defined by `border`, orientation defined by `vertical` (when `true`, the hexagon points along
/// the `y` axis), and colors for outline given by `border_color` and fill by `fill_color`.
pub fn draw_hexagon(
    x: f32,
    y: f32,
    size: f32,
    border: f32,
    vertical: bool,
    border_color: Color,
    fill_color: Color,
) {
    let rotation = if vertical { 90. } else { 0. };
    draw_poly(x, y, 6, size, rotation, fill_color);
    if border > 0. {
        draw_poly_lines(x, y, 6, size, rotation, border, border_color);
    }
}

/// Draws a solid regular polygon centered at `[x, y]` with a given number of `sides`, `radius`,
/// clockwise `rotation` (in degrees) and `color`.
pub fn draw_poly(x: f32, y: f32, sides: u8, radius: f32, rotation: f32, color: Color) {
    let context = get_context();

    let mut vertices = Vec::<Vertex>::with_capacity(sides as usize + 2);
    let mut indices = Vec::<u16>::with_capacity(sides as usize * 3);

    let rot = rotation.to_radians();
    vertices.push(Vertex::new(x, y, 0., 0., 0., color));
    for i in 0..sides + 1 {
        let rx = (i as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).cos();
        let ry = (i as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).sin();

        let vertex = Vertex::new(x + radius * rx, y + radius * ry, 0., rx, ry, color);

        vertices.push(vertex);

        if i != sides {
            indices.extend_from_slice(&[0, i as u16 + 1, i as u16 + 2]);
        }
    }

    context.gl.texture(None);
    context.gl.draw_mode(DrawMode::Triangles);
    context.gl.geometry(&vertices, &indices);
}

/// Draws a regular polygon outline centered at `[x, y]` with a given number of `sides`, `radius`,
/// clockwise `rotation` (in degrees), line `thickness`, and `color`.
pub fn draw_poly_lines(
    x: f32,
    y: f32,
    sides: u8,
    radius: f32,
    rotation: f32,
    thickness: f32,
    color: Color,
) {
    let rot = rotation.to_radians();

    for i in 0..sides {
        let rx = (i as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).cos();
        let ry = (i as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).sin();

        let p0 = vec2(x + radius * rx, y + radius * ry);

        let rx = ((i + 1) as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).cos();
        let ry = ((i + 1) as f32 / sides as f32 * std::f32::consts::PI * 2. + rot).sin();

        let p1 = vec2(x + radius * rx, y + radius * ry);

        draw_line(p0.x, p0.y, p1.x, p1.y, thickness, color);
    }
}

/// Draws a solid circle centered at `[x, y]` with a given radius `r` and `color`.
pub fn draw_circle(x: f32, y: f32, r: f32, color: Color) {
    draw_poly(x, y, 20, r, 0., color);
}

/// Draws a circle outline centered at `[x, y]` with a given radius, line `thickness` and `color`.
pub fn draw_circle_lines(x: f32, y: f32, r: f32, thickness: f32, color: Color) {
    draw_poly_lines(x, y, 20, r, 0., thickness, color);
}

/// Draws a line between points `[x1, y1]` and `[x2, y2]` with a given `thickness` and `color`.
pub fn draw_line(x1: f32, y1: f32, x2: f32, y2: f32, thickness: f32, color: Color) {
    let context = get_context();
    let dx = x2 - x1;
    let dy = y2 - y1;

    // https://stackoverflow.com/questions/1243614/how-do-i-calculate-the-normal-vector-of-a-line-segment

    let nx = -dy;
    let ny = dx;

    let tlen = (nx * nx + ny * ny).sqrt() / (thickness * 0.5);
    if tlen < std::f32::EPSILON {
        return;
    }
    let tx = nx / tlen;
    let ty = ny / tlen;

    context.gl.texture(None);
    context.gl.draw_mode(DrawMode::Triangles);
    context.gl.geometry(
        &[
            Vertex::new(x1 + tx, y1 + ty, 0., 0., 0., color),
            Vertex::new(x1 - tx, y1 - ty, 0., 0., 0., color),
            Vertex::new(x2 + tx, y2 + ty, 0., 0., 0., color),
            Vertex::new(x2 - tx, y2 - ty, 0., 0., 0., color),
        ],
        &[0, 1, 2, 2, 1, 3],
    );
}