MegaFractal

Renders UltraFractal .upr parameter files on your GPU via OpenCL, with progressive preview.

Windows download

Self-contained zip: megafractal.exe (CLI) + megafractal_gui.exe (progressive preview) + example scenes. The GUI fetches the third-party UF formula database on demand (File → Download UF formulas). No runtime DLL deps.
Needs any OpenCL 1.2+ GPU. FP32 by default; pass -double for FP64 deep zooms.

Features

UltraFractal .upr compat — parses the formula language (if/while/repeat, complex math, transforms, gradients, per-layer coloring) and translates to OpenCL C.
Multi-layer rendering — every AA sample evaluates every layer and composites bottom-up in registers; 13 blend modes including HSL variants.
Progressive preview — SDL2 + ImGui GUI shows 1 spp instantly and refines in place at integer-log2 milestones (SL1, SL2, SL4, …).
Live tonemap — exposure and contrast sliders retonemap via a separate imaging kernel; no accumulator round-trip.
TDR-safe dispatch — one-tile probe picks tile size and seeds tiles_per_flush so each finish() stays under a 500 ms budget (4× below the 2 s Windows TDR default).
Device-aware auto-tune — discrete GPUs unroll to 8 samples/pass; iGPUs stay at 1 to respect register pressure (chosen from CL_DEVICE_HOST_UNIFIED_MEMORY).
Supersampling — Roberts R2 quasi-random + per-pixel blue-noise Cranley–Patterson rotation, tent filter.
Linear-light pipeline — gradient LUT decoded to linear, blending and AA integrate in linear, single sRGB encode at the uchar4 write.

Compatibility gallery

greenpurple reference render — greenpurpleregression

loopy reference render — loopyregression

Source

View on Codeberg

C++17 + OpenCL. Contributions of UltraFractal scenes (.upr + reference render at ~1024×640) are welcome — see README.md → Contributing scenes.