v1.2.1

3D

• Occlusion between solids. A solid can now hide what is behind it. Lines drawn after a solid has been registered as an occluder are cut by its silhouette. When no occluders are registered, the cost is negligible. Counters report how many lines were cut and how many occluders were refused, so the feature can be verified at run time.
• Correct proportions. The projection uses the same scale on both axes, so squares come out square and circles round.
• Per-axis view window. The visible window can be set independently in x and y to use the full portrait screen.
• Field-of-view queries. Games can ask for the horizontal and vertical field of view actually on screen, instead of hard-coding it.

Drawing

• Stable brightness on static screens. A screen drawn at a single intensity no longer fades out over time.

Calibration

• New ring-burst test figure. It separates the per-stroke error from the length-proportional error. It also shows whether the frame fitted, so overload is not mistaken for distortion.
• Figure selector on button 1. The same setting can be judged on the text, the wheel or the rings without leaving it.
• Audio output setting on screen. Switches show words instead of numbers.
• Joystick centre measured on entry, so navigation works on consoles whose stick does not rest at zero.

Audio and storage

• Stereo output on the audio jack.
• Hardware SPI for the SD card at 12.5 MHz, much faster than before.
• Microsecond clock available to games.

Examples

• Geometry test card: checks screen proportions and visible extent on a console.
• Occlusion demo: the same scene with occlusion on and off, and a worked example of how to use it.