float ringMask(float2 uv)
{
	float2 centered = uv * 2.0 - 1.0;
	float radius = length(centered);
	float ring = 1.0 - smoothstep(0.015, 0.035, abs(radius - 0.55));
	float cross = 1.0 - smoothstep(0.006, 0.018, min(abs(centered.x), abs(centered.y)));
	return saturate(max(ring, cross));
}

float gridMask(float2 uv)
{
	float2 cell = abs(frac(uv * max(scale, 1.0)) - 0.5);
	float line = 1.0 - smoothstep(0.455, 0.495, max(cell.x, cell.y));
	return saturate(line * 0.55);
}

float4 buildMask(ShaderContext context)
{
	float mask = saturate(max(ringMask(context.uv), gridMask(context.uv)));
	return float4(context.sourceColor.rgb, mask);
}

float4 applyMask(ShaderContext context)
{
	float4 generated = sampleVideo(context.uv);
	float mask = generated.a;
	float checker = step(0.5, frac((context.uv.x + context.uv.y) * max(scale, 1.0)));
	float3 testColor = lerp(float3(0.0, 0.75, 1.0), float3(1.0, 0.1, 0.85), checker);
	float3 base = generated.rgb;
	float3 color = lerp(base, testColor, mask * saturate(intensity));
	return float4(color, 1.0);
}

float4 shadeVideo(ShaderContext context)
{
	return applyMask(context);
}
