#version 460 core
#define STAGE_COMPUTE 1
// the water on the windscreens (water_sim.glsl): the mask of the wipers of a glass baked into its map, once, when the glass is
// set up. a thread per texel of the map; the glass is water_counts.z

#include "common.glsl"
#include "water_sim.glsl"

layout(local_size_x = WATER_GROUP_SIZE) in;

// the mask of the wipers of the material of the glass (wipermask)
layout(binding = WATER_MASK_TEX) uniform sampler2D water_mask;

void main()
{
	uint slot = water_counts.z;
	uint texel = gl_GlobalInvocationID.x;
	if ((slot >= uint(WATER_SLOTS)) || (texel >= uint(WATER_MAP * WATER_MAP)))
		return;
	vec2 uv = (vec2(float(texel % uint(WATER_MAP)), float(texel / uint(WATER_MAP))) + 0.5) / float(WATER_MAP);
	// as much of the mask as a texel of the map covers
	float lod = log2(max(float(textureSize(water_mask, 0).x) / float(WATER_MAP), 1.0));
	water_blades[slot * uint(WATER_MAP * WATER_MAP) + texel] = textureLod(water_mask, uv, lod);
}