Package eu.svjatoslav.sixth.e3d.renderer.raster.shapes.basic.line

Class Line

java.lang.Object

eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractShape

eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractCoordinateShape

eu.svjatoslav.sixth.e3d.renderer.raster.shapes.basic.line.Line

public class Line
extends AbstractCoordinateShape

A 3D line segment with perspective-correct width and alpha blending.

This class represents a line between two 3D points, rendered with a specified width that adjusts based on perspective (distance from the viewer). The line is drawn using interpolators to handle edge cases and alpha blending for transparency effects.

The rendering algorithm: 1. For thin lines (below a threshold), draws single-pixel lines with alpha adjustment based on perspective. 2. For thicker lines, creates four interpolators to define the line's rectangular area and fills it scanline by scanline.

Note: The width is scaled by the LINE_WIDTH_MULTIPLIER and adjusted based on the distance from the viewer (z-coordinate) to maintain a consistent visual size.

Field Summary

Fields

Modifier and Type	Field	Description
Color	color	Color of the line.
final double	width	width of the line.

Fields inherited from class eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractCoordinateShape

shapeId, vertices

Fields inherited from class eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractShape

cachedBoundingBox, mouseInteractionController

Constructor Summary

Constructors

Constructor	Description
Line(Point3D point1, Point3D point2, Color color, double width)	Creates a line between two points with the specified color and width.
Line(Line parentLine)	Creates a copy of an existing line with cloned coordinates and color.

Method Summary

Modifier and Type	Method	Description
protected double	getScreenXMargin(RenderingContext renderingContext)	The thick-line widening is perpendicular to the line direction, so it reaches past the vertex range on the X axis exactly as much as on Y.
protected double	getScreenYMargin(RenderingContext renderingContext)	The thick-line path widens the line perpendicular to its direction by the projected endpoint radii, reaching beyond the vertex Y range.
void	paint(RenderingContext buffer)	Renders this line to the screen using perspective-correct width and alpha blending.

Methods inherited from class eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractCoordinateShape

clippedVertices, getBoundingBox, getBspRank, getZ, getZ, onScreenMaxX, onScreenMaxY, onScreenMinX, onScreenMinY, setBspRank, setZ, transform, translate

Methods inherited from class eu.svjatoslav.sixth.e3d.renderer.raster.shapes.AbstractShape

getTransformWeight, invalidateBounds, setMouseInteractionController

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

width

public final double width

width of the line.

color

public Color color

Color of the line.

Constructor Details

Line

public Line(Line parentLine)

Creates a copy of an existing line with cloned coordinates and color.

Parameters:

parentLine - the line to copy

Line

public Line(Point3D point1,
 Point3D point2,
 Color color,
 double width)

Creates a line between two points with the specified color and width.

Parameters:

point1 - the starting point of the line

point2 - the ending point of the line

color - the color of the line

width - the width of the line in world units

Method Details

getScreenYMargin

protected double getScreenYMargin(RenderingContext renderingContext)

The thick-line path widens the line perpendicular to its direction by the projected endpoint radii, reaching beyond the vertex Y range. The thin paths stay within the vertex Y range, but there the radius is below 1 pixel anyway.

Overrides:

getScreenYMargin in class AbstractCoordinateShape

Parameters:

renderingContext - the rendering context (provides projection parameters for size computation)

Returns:

the Y margin in screen pixels (0 = vertex bounds are exact)

getScreenXMargin

protected double getScreenXMargin(RenderingContext renderingContext)

The thick-line widening is perpendicular to the line direction, so it reaches past the vertex range on the X axis exactly as much as on Y.

Overrides:

getScreenXMargin in class AbstractCoordinateShape

Parameters:

renderingContext - the rendering context (provides projection parameters for size computation)

Returns:

the X margin in screen pixels (0 = vertex bounds are exact)

paint

public void paint(RenderingContext buffer)

Renders this line to the screen using perspective-correct width and alpha blending.

This method handles two rendering modes:

• Thin lines: When the projected width is below threshold, draws single-pixel lines with alpha adjusted for sub-pixel appearance.
• Thick lines: Creates four edge interpolators and fills the rectangular area scanline by scanline with perspective-correct alpha fading at edges.

Specified by:

paint in class AbstractCoordinateShape

Parameters:

buffer - the rendering context containing the pixel buffer