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Overview

Mars-RS renders a visual representation of the VEX Robotics Competition Over Under game field. The field display includes game elements, scoring zones, and properly scaled dimensions.

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Field Dimensions

The field is rendered as a 12×12 foot square: 
let size = ft() * 12.0 * 0.9; // 90% of 12 feet
self.size = size;
self.pos = (
    screen_width() / 2.0 - size / 2.0, 
    screen_height() / 2.0 - size / 2.0
);

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Scaling Function

The ft() function converts feet to screen pixels: 
pub fn ft() -> f32 {
    screen_width().min(screen_height()) / 12.0
}
This ensures the field scales proportionally to fit the window while maintaining the correct aspect ratio.

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Field Tiles

The field consists of a 6×6 grid of tiles in a checkerboard pattern: 
let tileSize = self.size / 6.0;
let colors = [hex!(0xDCABDF), hex!(0xC792DF)];

for i in 0..6 {
    for j in 0..6 {
        let index = (i+j) % 2;
        draw_rectangle(
            self.pos.0 + i as f32 * tileSize, 
            self.pos.1 + j as f32 * tileSize, 
            tileSize, 
            tileSize, 
            colors[index]
        );
    }
}
Tile Colors:
  • Light purple: #DCABDF
  • Dark purple: #C792DF

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Game Elements

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Triballs

Triballs are the game pieces in VEX Over Under. They are represented as three-sided objects with curved edges: 
pub struct Triball {
    pub size: f32,
    pub pos: (f32, f32),
    pub rotation: f32,
    pub vel: Vec3,
    pub accel: Vec3
}

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Rendering

Triballs are drawn using three arc segments: 
let v1 = util::rotate![0.0, self.size * R303, self.rotation, self.pos]; 
let v2 = util::rotate![-self.size / 2.0,-self.size * R306, self.rotation, self.pos];
let v3 = util::rotate![self.size / 2.0, -self.size * R306, self.rotation, self.pos];

draw_arc(v1, self.size, self.rotation - PI / 3.0, self.rotation - 2.0 * PI/3.0, GREEN);
draw_arc(v2, self.size, self.rotation, self.rotation + PI / 3.0, GREEN);
draw_arc(v3, self.size, self.rotation + 2.0 * PI/3.0, self.rotation + 3.0 * PI/3.0, GREEN);
Where:
  • R303 = 0.57735026919 (√3/3)
  • R306 = 0.28867513459 (√3/6)
Triballs are rendered in green color and rotate based on their rotation property.

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Scoring Zones

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Goals

The field features goals on both sides with nets:

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Blue Goal (Left Side)

// Goal perimeter
draw_circle(x + tileSize, y + 2.0 * tileSize, 15.0, blue);
draw_circle(x + tileSize, ylow - 2.0 * tileSize, 15.0, blue);
draw_line(x + tileSize, y + 2.0 * tileSize, x + tileSize, ylow - 2.0 * tileSize, thin, ablue);

// Net pattern
for i in 1..10 {
    let inc = tileSize / 5.0 * i as f32;
    draw_line(x, y + 2.0 * tileSize + inc, x + tileSize, y+2.0 * tileSize + inc, thin/3.0, blue);
}
for i in 1..5 {
    let inc = tileSize / 5.0 * i as f32;
    draw_line(x + inc, y + 2.0 * tileSize, x + inc, ylow - 2.0 * tileSize, thin/3.0, blue);
}
Blue Goal Colors:
  • Primary: #35A7FF
  • Accent: #4F7CAC

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Red Goal (Right Side)

// Goal perimeter
draw_circle(xmax - tileSize, y + 2.0 * tileSize, 15.0, red);
draw_circle(xmax - tileSize, ylow - 2.0 * tileSize, 15.0, red);
draw_line(xmax - tileSize, y + 2.0 * tileSize, xmax - tileSize, ylow - 2.0 * tileSize, thin, ared);

// Net pattern (similar to blue side)
Red Goal Colors:
  • Primary: #FF5964
  • Accent: #90323D

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Load Zones

Load zones are marked in the corners of the field: 
// Red load zones
draw_line(x+tileSize - 6.0, y + 6.0, x + 6.0, y+tileSize - 6.0, thick, red);
draw_line(x+tileSize - 6.0, ylow - 6.0, x + 6.0, ylow-tileSize + 6.0, thick, red);

// Blue load zones
draw_line(xmax - tileSize + 6.0, y + 6.0, xmax - 6.0, y+tileSize - 6.0, thick, blue);
draw_line(xmax - tileSize + 6.0, ylow - 6.0, xmax - 6.0, ylow-tileSize + 6.0, thick, blue);
Load zones are diagonal lines in the corner tiles.

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Field Barrier

The center barrier divides the field: 
let grey = hex!(0x38618C);

// Vertical barrier
draw_line(xhalf, y + tileSize, xhalf, ylow - tileSize, thick, grey);

// Horizontal barriers
draw_line(xhalf - tileSize, y + tileSize, xhalf+tileSize, y+tileSize, thick, grey);
draw_circle(xhalf, y + tileSize, 7.0, hex!(0xFFE74C)); // Yellow circle

draw_line(xhalf - tileSize, ylow - tileSize, xhalf+tileSize, ylow-tileSize, thick, grey);
draw_circle(xhalf, ylow - tileSize, 7.0, hex!(0xFFE74C)); // Yellow circle
The barrier includes:
  • Grey lines (#38618C)
  • Yellow circles at intersections (#FFE74C)

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Elevation Bars

Elevation bars allow robots to score points by hanging: 
// Blue alliance bar (top)
draw_line(xhalf, y, xhalf, y + tileSize, thick, blue);

// Red alliance bar (bottom)
draw_line(xhalf, ylow, xhalf, ylow - tileSize, thick, red);
Bars extend one tile from the field edge at the center line.

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Field Border

The entire field is outlined with a border: 
draw_rectangle_lines(self.pos.0, self.pos.1, self.size, self.size, 6.0, hex!(0xD0C4DF));
Border Color: #D0C4DF (light purple) Border Width: 6 pixels

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Coordinate System

The field uses a coordinate system where:
  • (0, 0) is at self.pos (top-left corner of field)
  • X-axis increases from left to right
  • Y-axis increases from top to bottom
  • One tile = size / 6.0 pixels

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Converting Measurements

// 1 foot in screen units
let one_foot = ft();

// Robot size (15 inches = 1.25 feet)
self.robotSize = ft() / 12.0 * 15.0 / 2.0;

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Line Thickness

Different elements use different line thicknesses: 
let thick = tileSize / 8.0;   // Thick lines (barriers, load zones)
let thin = tileSize / 18.0;   // Thin lines (goal perimeter)
let net = thin / 3.0;         // Net lines

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Color Palette

The field uses a consistent color scheme:
ElementHex CodeRGB
Tile Light#DCABDF(220, 171, 223)
Tile Dark#C792DF(199, 146, 223)
Border#D0C4DF(208, 196, 223)
Red Alliance#FF5964(255, 89, 100)
Red Accent#90323D(144, 50, 61)
Blue Alliance#35A7FF(53, 167, 255)
Blue Accent#4F7CAC(79, 124, 172)
Barrier#38618C(56, 97, 140)
Yellow Accent#FFE74C(255, 231, 76)
Triball#00FF00(0, 255, 0)

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Physics (Experimental)

Triball physics is defined but currently disabled: 
pub fn physics(&mut self) {
    // Commented out - not currently implemented
    // self.vel += self.accel;
    // self.pos.0 += self.vel.x;
    // self.pos.1 += self.vel.y;
    // self.rotation += self.vel.z;
}
Physics simulation for triballs is planned but not yet active.

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Field Initialization

Create a new field with: 
pub fn new() -> Field {
    let size = screen_width().min(screen_height()) * 0.8;
    Field { 
        size, 
        pos: (
            screen_width() / 2.0 - size / 2.0, 
            screen_height() / 2.0 - size / 2.0
        ), 
        triballs: Vec::new()
    }
}

Path Creation

Design paths on the field layout

Autonomous Mode

Execute movements on the field

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