eppz! Lines

part of Unity.Library.eppz

Lightweight OpenGL line rendering for Unity. Like Debug.DrawLine in Game view.

Simple drawing API goes like below (see example scene in Scenes for more).

DrawLine(Vector2.up, Vector2.down, Color.white);
DrawCircle(Vector2.zero, 10.0f, Color.yellow);

Usage

1. Add a LineRendererCamera script to your camera.
2. Hook up a material.
3. A. Inspector only. Add a CachedLineRenderer to a GameObject to define lines in inspector directly.
4. B. Code. Implement DirectLineRenderer in a new script.

See example scenes in Scenes for more.

Under the hood

The library uses OpenGL immediate mode drawing in the Camera.OnPostRender() template metod. While the lines in the scene gets batches into a single draw call, this library is not really meant for production use, mainly useful for debugging purposes.

...
GL.Begin(GL.LINES);
foreach (EPPZ.Lines.Line eachLine in lineBatch)
{
    GL.Color(eachLine.color);
    GL.Vertex(eachLine.from);
    GL.Vertex(eachLine.to);
}
GL.End();
...

The camera also calls Debug.DrawLine calls on Update(), so you can see your drawings in the scene view as well.

Implement DirectLineRenderer

There is a single OnDraw() template method you can override, and impement your drawing code there.

This method will be invoked from LineRendererCamera, batch you line definitions for the given frame, then draw them in OnPostRender() (see above).

public class Line : DirectLineRenderer
{
	protected override void OnDraw()
	{
		DrawLine(Vector2.up, Vector2.down, Color.white);
	}
}

Find more drawing code template DrawPoints(), DrawRect(), DrawCircle(), and DrawPointsWithTransform(), DrawRectWithTransform(), DrawCircleWithTransform() in LineRendererBase.cs. You can see there how to make you own drawing methods.

Example

The code for the Lissajous curve above goes like below. It uses the same DrawLine() used before, the rest is trigonometry math.

using UnityEngine;
using System.Collections;


public class Lissajous : EPPZ.Lines.DirectLineRenderer
{


	float t = 0.0f;

	const float resolution = 0.01f;
	const float speed = 0.2f;


	protected override void OnDraw ()
	{
		// Draw Lissajous curve segments.
		Vector2 from = Function(t, 0.0f);
		for (float s = resolution; s < Mathf.PI * (2.0 + resolution); s += resolution)
		{
			Vector2 to = Function(t, s);

			// Direct draw.
			DrawLine(from, to, Color.white);

			from = to;
		}

		// Step.
		t += speed;
	}

	Vector2 Function(float t, float s)
	{
		// More at https://en.wikipedia.org/wiki/Lissajous_curve
		return new Vector2(
			Mathf.Sin (5 * s + t),
			Mathf.Sin (4 * s + t)
		);
	}
}

License

Licensed under the MIT license.