GLSL.io Transition (v1)

TilesScanline.glsl

#ifdef GL_ES
precision highp float;
#endif
uniform sampler2D from, to;
uniform float progress;
uniform vec2 resolution;

const vec2 tileSize = vec2(64, 64);

const float checkerDistance = 0.015;

const bool flipX = true;
const bool flipY = false;

const bool preTileSingleColor = false; ///8bit ftw
const bool postTileSingleColor = false; ///8bit ftw

vec2 tile2Global(vec2 tex, vec2 tileNum, bool tileSingleColor) {
    vec2 perTile = tileSize / resolution.xy;
    return tileNum * perTile + (tileSingleColor ? vec2(0) : tex*perTile);
}

void main(void)
{
	vec2 uv = gl_FragCoord.xy / resolution.xy;

    vec4 fragColor = vec4(1, 1, 0, 1);

    vec2 posInTile = mod(vec2(gl_FragCoord), tileSize);
    vec2 tileNum = floor(vec2(gl_FragCoord)/ tileSize);
    int num = int(tileNum.x);
    vec2 totalTiles = ceil(resolution.xy / tileSize);
    float countTiles = totalTiles.x * totalTiles.y;
     
	vec2 perTile = ceil(tileSize / resolution.xy);
    float offset = 0.0;   //curtain
    //   scanline horizontal
    offset = (tileNum.x + tileNum.y * totalTiles.x) / countTiles;
    //   and scanline vertical ofc
    //offset = (tileNum.y + tileNum.x * totalTiles.y) / countTiles;

    float timeOffset = (progress - offset) * countTiles;
    timeOffset = clamp(timeOffset, 0.0, 0.5);
    
    float sinTime = 1.0 - abs(cos(fract(timeOffset) * 3.1415926));
    
    fragColor.rg = uv;
    fragColor.b = sinTime;
    
    vec2 texC = posInTile / tileSize;
    
    if (sinTime <= 0.5){
    

        if (flipX) {
            if ((texC.x < sinTime) || (texC.x > 1.0 - sinTime)){
                discard;
            }
            if (texC.x < 0.5) {
                texC.x = (texC.x - sinTime) * 0.5 / (0.5 - sinTime);
            } else {
                texC.x = (texC.x - 0.5) * 0.5 / (0.5 - sinTime) + 0.5;
            }
        }

        if (flipY) {
            if ((texC.y < sinTime) || (texC.y > 1.0 - sinTime)){
                discard;
            }
            if (texC.y < 0.5) {
                texC.y = (texC.y - sinTime) * 0.5 / (0.5 - sinTime);
            } else {
                texC.y = (texC.y - 0.5) * 0.5 / (0.5 - sinTime) + 0.5;
            }
        }

        fragColor = texture2D(from, tile2Global(texC, tileNum, preTileSingleColor));

    } else {
        if (flipX) {
            if ((texC.x > sinTime) || (texC.x < 1.0 - sinTime)){
                discard;
            }
            if (texC.x < 0.5) {
                texC.x = (texC.x - sinTime) * 0.5 / (0.5 - sinTime);
            } else {
                texC.x = (texC.x - 0.5) * 0.5 / (0.5 - sinTime) + 0.5;
            }
            texC.x = 1.0 - texC.x;
        }

        if (flipY) {
            if ((texC.y > sinTime) || (texC.y < 1.0 - sinTime)){
                discard;
            }
            if (texC.y < 0.5) {
                texC.y = (texC.y - sinTime) * 0.5 / (0.5 - sinTime);
            } else {
                texC.y = (texC.y - 0.5) * 0.5 / (0.5 - sinTime) + 0.5;
            }
            texC.y = 1.0 - texC.y;
        }

        fragColor.rgb = texture2D(to, tile2Global(texC, tileNum, postTileSingleColor)).rgb;

    }
    gl_FragColor = fragColor;
  
}

uniforms.default.json

{}

~LICENSE

GLSL.io Transition License (v1): 
The MIT License (MIT)

Copyright (C) 2014 contact@glsl.io

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.