Wrong source region when using BLIT_FLIP_X/Y with a partially clipped sprite

[aduros]

Wrong source region when using BLIT_FLIP_X/Y with a partially clipped sprite

[eXponenta]

Are you sure that bug still is reproduced?
Can i help with it, becuse it a will be required for my game.
My game use a atlass for movement animation, and flips can be used for avoid doubling right-left movements.

[aduros]

Yeah, it's still an issue. Here's a repro case:

import * as w4 from "./wasm4";

const skullWidth = 8;
const skullHeight = 16;
const skullFlags = 1; // BLIT_2BPP
const skull = memory.data<u8>([ 0xaa,0x80,0xa8,0x3f,0xa3,0xff,0xa3,0xff,0x8f,0xff,0x8f,0xff,0x3c,0x03,0x30,0x53,0x30,0x53,0x30,0x03,0x8c,0x0f,0xa3,0xfc,0xa8,0xfc,0xa8,0xff,0xa8,0xf3,0xaa,0x08 ]);

let x = -16;
let frame = 0;

store<u16>(w4.DRAW_COLORS, 0x2014);

export function update (): void {
    let x = i32(16*Math.sin(0.01*frame)+144);

    // Draw skull left half
    w4.blit(skull, x, 64, skullWidth, skullHeight, skullFlags);

    // BUG: Draw flipped skull right half
    w4.blit(skull, x+skullWidth, 64, skullWidth, skullHeight, skullFlags | w4.BLIT_FLIP_X);

    ++frame;
}

You can see that as the flipped right half of the sprite is partially off screen, it's not drawn correctly. It also happens when using BLIT_ROTATE.

If you want to take a stab at this, the fix is probably in the sx/sy calculation in framebuffer.js.

[JerwuQu]

This is still an issue in 2.2.0. Might give a shot at fixing it later tonight unless it's already in progress...?

#include "wasm4.h"

const uint8_t smiley[] = {
    0b11000011,
    0b10000001,
    0b00100100,
    0b00100100,
    0b00000000,
    0b00100100,
    0b10011001,
    0b11000011,
};

void update () {
    *DRAW_COLORS = 2;

    blit(smiley, 0, 145, 8, 8, BLIT_1BPP);
    blit(smiley, 20, 150, 8, 8, BLIT_1BPP);
    blit(smiley, 40, 155, 8, 8, BLIT_1BPP);
    blit(smiley, 60, 160, 8, 8, BLIT_1BPP);

    blit(smiley, 80, 145, 8, 8, BLIT_1BPP | BLIT_FLIP_Y);
    blit(smiley, 100, 150, 8, 8, BLIT_1BPP | BLIT_FLIP_Y);
    blit(smiley, 120, 155, 8, 8, BLIT_1BPP | BLIT_FLIP_Y);
    blit(smiley, 140, 160, 8, 8, BLIT_1BPP | BLIT_FLIP_Y);
}

[aduros]

Please do @JerwuQu! A fix would be much appreciated 😃

[JerwuQu]

Fixed in #319