Instanced Line Render Demo

Demo extension showcasing the instanced line and dot rendering API. Features an N-body gravity simulation, grid drawing, sine waves, edge tests, and traffic signal visualization.

Overview

util_instancedLineRenderDemo demonstrates the debugDrawer:drawLineInstance() and debugDrawer:drawDot() APIs with several visual demos. Includes an N-body simulation with history trails, grid comparisons (standard vs instanced lines), sine wave rendering, edge/width tests, and a traffic signal mock-up.

Extension path: lua/ge/extensions/util/instancedLineRenderDemo.lua

Exports (M)

Internals

N-Body Simulation

• Masses: 5 particles with random initial positions, velocities, and colors.
• Forces: Each particle is attracted toward origin (-32x) and repelled/attracted by other masses.
• History: Up to 10,000 line segments stored per mass for trail rendering.
• Rendering: Two copies - one with depth testing off, one with depth on (offset by 5 units).

Instanced Line API

-- Full signature:
debugDrawer:drawLineInstance(posA, posB, widthA, colorA, widthB, colorB, colOutlineA, colOutlineB, outLineMultiplier, endRoundCaps)

-- Simplified (uniform width/color):
debugDrawer:drawLineInstance(posA, posB, width, color, useDepth)

-- Dot:
debugDrawer:drawDot(pos, size, color, colOutline, outLineMultiplier)

Demo Components

Signal States

The traffic signal cycles through 4 states:

1. Red
2. Red + Yellow
3. Green
4. Yellow

How It Works

1. Load: extensions.load('util_instancedLineRenderDemo').
2. The simulation starts automatically.
3. Every frame, onPreRender updates physics and draws all demos near origin (0, 0, 3).
4. Commented-out demos (grid, sine, edge, signal) can be re-enabled in the source.

Lua Examples

-- Load the demo
extensions.load('util_instancedLineRenderDemo')

-- Key rendering calls used in the demo:
debugDrawer:drawLineInstance(p1, p2, 3, ColorF(1,0,0,1), true)
debugDrawer:drawDot(pos, 50, ColorF(0,1,0,1), ColorF(0,0,0,1), 1.2)
debugDrawer:drawLineInstance(p1, p2, 10, col1, 30, col2, bgColor, bgColor, 30)

Additional Exports

• M.onExtensionLoaded - (undocumented)
• M.onPreRender - (undocumented)

See Also

• Auto Annotation - Related reference
• Booster - Related reference
• Calibrate ESC - Related reference
• Game Engine Overview - Guide