WARP 1k by MB Maniax
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Z X R O T O Z O O M E R
1K Intro for ZX Spectrum
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Forever XXIV Demoparty (2026)
1K Intro Competition Entry
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CREDITS
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Idea & Programming: Shrek/MB Maniax
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REQUIREMENTS
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Platform: ZX Spectrum 48K
Size: 1005 bytes (1K)
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DESCRIPTION
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This 1K intro features two visual effects:
PART 1 - WAVING FLAG (Intro)
The "ZX" logo with rainbow background waves like a flag in the wind.
Each row and column is displaced using sine-wave offsets, creating
a 2D rubber-sheet deformation effect. The wave speed gradually
increases during the intro sequence.
PART 2 - ROTOZOOMER (Main Effect)
Classic rotozoomer effect with smooth rotation and zoom pulsation.
The texture rotates and zooms in/out continuously, creating a
hypnotic visual effect.
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TECHNICAL DETAILS
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ROTOZOOMER ALGORITHM:
The rotozoomer uses 8.8 fixed-point math for texture mapping.
For each screen pixel (x,y), we calculate texture coordinates (u,v):
u = startU + x*dUx + y*dUy
v = startV + x*dVx + y*dVy
Where:
dUx = cos(angle) * zoom / 128
dVx = sin(angle) * zoom / 128
dUy = -sin(angle) * zoom / 128 (perpendicular)
dVy = cos(angle) * zoom / 128
The angle changes smoothly using sine-modulated speed (accelerates
and decelerates). Zoom pulsates using another sine wave.
SINE TABLE:
Only first quadrant (64 values) is stored in ROM. The remaining
192 values are generated at runtime using symmetry:
- Q2 (64-127): mirror of Q1
- Q3 (128-191): negation of Q1
- Q4 (192-255): negation of Q2
TEXTURE:
32x32 attribute texture generated at runtime:
- Rainbow diagonal stripes (Red, Yellow, Green, Blue)
- "Z" letter in white (bright)
- "X" letter in black
Letters are defined as compact data (Y, X, length triplets).
WAVING FLAG:
Pre-calculated offset tables for X (24 values) and Y (32 values)
axes. Each offset = sin(coordinate * 4 + phase) / 32, giving
smooth +-3 pixel displacement. Phase increases each frame.
SOUND:
AY-3-8910 white noise generator creates ambient wind-like sound.
Noise period set to 31 for deep rumble, volume kept low (3/15).
MEMORY OPTIMIZATION:
All runtime variables (sin table, texture, offsets) use EQU
addresses beyond the binary - they exist only in RAM, not in
the 1K binary file.
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SIZE BREAKDOWN (approximate)
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Screen clear & init: ~30 bytes
Sine table generator: ~50 bytes
Sine Q1 data: 64 bytes
Texture generator: ~80 bytes
Letter data (Z + X): ~90 bytes
Wave effect (intro): ~150 bytes
Rotozoomer: ~300 bytes
Math routines: ~100 bytes
AY sound init: ~40 bytes
Main loop & control: ~50 bytes
Misc: ~70 bytes
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TOTAL: ~1024 bytes
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CONTROLS
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SPACE - Exit to BASIC (in Rotazoomer part)
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GREETINGS
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Greetings fly to all ZX Spectrum sceners and Forever party visitors!
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(c) 2026 Shrek / MB Maniax
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