Package eu.svjatoslav.sixth.e3d.headless

Class PixelAssertions

java.lang.Object

eu.svjatoslav.sixth.e3d.headless.PixelAssertions

public final class PixelAssertions
extends Object

Pixel-level assertions for headless render verification.

The recurring question in rasterizer debugging is "did this region of the screen actually get painted?" These helpers answer it against a BufferedImage produced by Snapshot, treating one chosen background color as "unpainted". All methods are static and return data rather than throwing, so callers decide how to report failures.

Example — assert the floor rendered (no holes from clipping):

 BufferedImage image = Snapshot.render(scene, lighting, pose, 640, 480);
 double holes = PixelAssertions.unpaintedFraction(image, 0x00000000,
         0.15, 0.45, 0.85, 1.0);  // lower-center band
 if (holes > 0.05)
     throw new AssertionError("floor has holes: " + holes);
 

See Also:

• Snapshot
• GoldenImage

Method Summary

Modifier and Type	Method	Description
static long	countColor(BufferedImage image, int rgb)	Counts pixels equal (in RGB) to the given color.
static long	countPainted(BufferedImage image, int backgroundRgb)	Counts pixels in the whole image that differ from the background color.
static String	dumpPixelGrid(BufferedImage image, int cx, int cy, int radius, int stride)	Dumps a grid of pixel colors around a point as text, for eyeballing gradients/edges in a failing render.
static double	unpaintedFraction(BufferedImage image, int backgroundRgb)	Fraction of pixels in the whole image that still equal the background color (i.e.
static double	unpaintedFraction(BufferedImage image, int backgroundRgb, double x0, double y0, double x1, double y1)	Fraction of pixels inside a relative rectangle that still equal the background color.

Methods inherited from class java.lang.Object

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

Method Details

unpaintedFraction

public static double unpaintedFraction(BufferedImage image,
 int backgroundRgb)

Fraction of pixels in the whole image that still equal the background color (i.e. nothing was painted there).

Parameters:

image - the rendered image

backgroundRgb - the background color (RGB, alpha ignored)

Returns:

fraction in [0, 1]

unpaintedFraction

public static double unpaintedFraction(BufferedImage image,
 int backgroundRgb,
 double x0,
 double y0,
 double x1,
 double y1)

Fraction of pixels inside a relative rectangle that still equal the background color.

Parameters:

image - the rendered image

backgroundRgb - the background color (RGB, alpha ignored)

x0 - left edge, fraction of width (0..1)

y0 - top edge, fraction of height (0..1)

x1 - right edge, fraction of width (0..1)

y1 - bottom edge, fraction of height (0..1)

Returns:

fraction in [0, 1]

countPainted

public static long countPainted(BufferedImage image,
 int backgroundRgb)

Counts pixels in the whole image that differ from the background color.

Parameters:

image - the rendered image

backgroundRgb - the background color (RGB, alpha ignored)

Returns:

number of painted pixels

countColor

public static long countColor(BufferedImage image,
 int rgb)

Counts pixels equal (in RGB) to the given color. Useful with flat test colors: "how much of the red triangle made it to the screen?"

Parameters:

image - the rendered image

rgb - the color to count (alpha ignored)

Returns:

number of matching pixels

dumpPixelGrid

public static String dumpPixelGrid(BufferedImage image,
 int cx,
 int cy,
 int radius,
 int stride)

Dumps a grid of pixel colors around a point as text, for eyeballing gradients/edges in a failing render. Samples every stride pixels, formatted as RRGGBB hex, one row per line.

Parameters:

image - the rendered image

cx - center X in pixels

cy - center Y in pixels

radius - grid extends this many samples in each direction

stride - pixels between samples

Returns:

multi-line hex grid string