GlitchShader.metal

//
//  G8Shaders.metal
//  GenerateMetal-iOS
//
//  Created by Omar Juarez Ortiz on 2019-02-25.
//  Copyright © 2019 Generate Software Inc. All rights reserved.
//

#include <metal_stdlib>
#include "MTIShaderLib.h"
#include "G8ShaderFunctions.h"

using namespace metal;

namespace metalpetal {
    namespace g8shaders {
        fragment float4 glitch1(VertexOut vertexIn [[stage_in]],
                                texture2d<float, access::sample> sourceTexture [[texture(0)]],
                                sampler sourceSampler [[sampler(0)]],
                                constant float &time [[buffer(0)]]){
            float2 resolution = float2(sourceTexture.get_width(), sourceTexture.get_height());
            float2 vUv = vertexIn.textureCoordinate;
            
            float strength = smoothstep(interval * 0.5, interval, interval - mod(time, interval));
            float2 shake = float2(strength * 8.0 + 0.5) * float2(
                                                                 random(float2(time)) * 2.0 - 1.0,
                                                                 random(float2(time * 2.0)) * 2.0 - 1.0
                                                                 ) / resolution;
            
            float y = vUv.y * resolution.y;
            float rgbWave = (
                             noise3D(float3(0.0, y * 0.01, time * 400.0)) * (2.0 + strength * 32.0)
                             * noise3D(float3(0.0, y * 0.02, time * 200.0)) * (1.0 + strength * 4.0)
                             + step(0.9995, sin(y * 0.005 + time * 1.6)) * 12.0
                             + step(0.9999, sin(y * 0.005 + time * 2.0)) * -18.0
                             ) / resolution.x;
            float rgbDiff = (6.0 + sin(time * 500.0 + vUv.y * 40.0) * (20.0 * strength + 1.0)) / resolution.x;
            float rgbUvX = vUv.x + rgbWave;
            float r = sourceTexture.sample(sourceSampler, float2(rgbUvX + rgbDiff, vUv.y) + shake).r;
            float g = sourceTexture.sample(sourceSampler, float2(rgbUvX, vUv.y) + shake).g;
            float b = sourceTexture.sample(sourceSampler, float2(rgbUvX - rgbDiff, vUv.y) + shake).b;
            
            float whiteNoise = (random(vUv + fmod(time, 10.0)) * 2.0 - 1.0) * (0.15 + strength * 0.15);
            
            float bnTime = floor(time * 20.0) * 200.0;
            float noiseX = step((snoise3D(float3(0.0, vUv.x * 3.0, bnTime)) + 1.0) / 2.0, 0.12 + strength * 0.3);
            float noiseY = step((snoise3D(float3(0.0, vUv.y * 3.0, bnTime)) + 1.0) / 2.0, 0.12 + strength * 0.3);
            float bnMask = noiseX * noiseY;
            float bnUvX = vUv.x + sin(bnTime) * 0.2 + rgbWave;
            float bnR = sourceTexture.sample(sourceSampler, float2(bnUvX + rgbDiff, vUv.y)).r * bnMask;
            float bnG = sourceTexture.sample(sourceSampler, float2(bnUvX, vUv.y)).g * bnMask;
            float bnB = sourceTexture.sample(sourceSampler, float2(bnUvX - rgbDiff, vUv.y)).b * bnMask;
            float4 blockNoise = float4(bnR, bnG, bnB, 1.0);
            
            float bnTime2 = floor(time * 25.0) * 300.0;
            float noiseX2 = step((snoise3D(float3(0.0, vUv.x * 2.0, bnTime2)) + 1.0) / 2.0, 0.12 + strength * 0.5);
            float noiseY2 = step((snoise3D(float3(0.0, vUv.y * 8.0, bnTime2)) + 1.0) / 2.0, 0.12 + strength * 0.3);
            float bnMask2 = noiseX2 * noiseY2;
            float bnR2 = sourceTexture.sample(sourceSampler, float2(bnUvX + rgbDiff, vUv.y)).r * bnMask2;
            float bnG2 = sourceTexture.sample(sourceSampler, float2(bnUvX, vUv.y)).g * bnMask2;
            float bnB2 = sourceTexture.sample(sourceSampler, float2(bnUvX - rgbDiff, vUv.y)).b * bnMask2;
            float4 blockNoise2 = float4(bnR2, bnG2, bnB2, 1.0);
            
            float waveNoise = (sin(vUv.y * 1200.0) + 1.0) / 2.0 * (0.15 + strength * 0.2);
            
            return float4(r, g, b, 1.0) * (1.0 - bnMask - bnMask2) + (whiteNoise + blockNoise + blockNoise2 - waveNoise);
        }
    
    }
}