Upshift

Added

• Real extra frames. The built-in frame generator now presents additional images between the frames the game renders, through the same window surface used by the real frame. The display receives more images than the renderer produces, on both the OpenGL and the Vulkan backend.
• Frame generation multiplier (1x–4x, default 2x): 2x presents one extra frame per rendered frame, 3x two, 4x three. 1x turns generation off.
• Force exact multiplier to present the selected number of frames even when the renderer already fills the display interval.

Behaviour

• Each extra frame is the last finished image, including the HUD, warped by the camera rotation predicted from the two previous poses. A pure rotation is a homography in clip space, so the warp needs one texture read and no depth buffer.
• Pacing is adaptive by default: the generator subtracts the time spent presenting extra frames from the measured interval between real frames and only adds as many frames as still fit into the refresh period. A scene that already holds the refresh rate pays nothing.
• Generation pauses while a screen is open, the game is paused or the window is minimized. Very small or very large rotation deltas (a teleport) are skipped instead of smearing the image.
• If presenting an extra frame fails, the window surface is released and the generator pauses for a few seconds before retrying; the game keeps rendering normal frames in the meantime.

Technical

• New FrameGenPresenter owns the pose history, the rotation homography, the output texture and the adaptive pacing.
• MinecraftMixin injects at HEAD and RETURN of Minecraft.renderFrame (no @Overwrite), so the extra presents happen before the next real frame starts and the previous finished image is the source.
• Config schema 8 adds frameGenMultiplier; existing configs migrate automatically.
• Java 21 bytecode.