#pragma once

#include <cmath>

#include <algorithm>

#include <halp/audio.hpp>

#include <halp/controls.hpp>

#include <halp/meta.hpp>

#include <halp/sample_accurate_controls.hpp>

#include <halp/texture.hpp>

namespace examples

{

struct TextureFilterExample

{

halp_meta(name, "My example texture filter");

halp_meta(c_name, "oscr_TextureFilterExample")

halp_meta(category, "Demo");

halp_meta(author, "Jean-Michaël Celerier");

halp_meta(description, "Example texture filter");

halp_meta(uuid, "3183d03e-9228-4d50-98e0-e7601dd16a2e");

struct

{

halp::texture_input<"In"> image;

halp::knob_f32<"Gain", halp::range{0., 255., 0.}> gain;

halp::knob_i32<"Downscale", halp::range{1, 32, 8}> downscale;

} inputs;

struct

{

halp::texture_output<"Out"> image;

} outputs;

// Some initialization can be done in the constructor.

TextureFilterExample() noexcept

{

// Allocate some initial data

outputs.image.create(1, 1);

}

void operator()()

{

auto& in_tex = inputs.image.texture;

auto& out_tex = outputs.image.texture;

// Since GPU readbacks are asynchronous: reading textures may take some time and

// thus the data may not be available from the beginning.

if(in_tex.bytes == nullptr)

return;

// Texture hasn't changed since last time, no need to recompute anything

if(!in_tex.changed)

return;

in_tex.changed = false;

const double downscale_factor = inputs.downscale;

const int small_w = in_tex.width / downscale_factor;

const int small_h = in_tex.height / downscale_factor;

// We (dirtily) downscale by a factor of downscale_factor

if(out_tex.width != small_w || out_tex.height != small_h)

outputs.image.create(small_w, small_h);

for(int y = 0; y < small_h; y++)

{

for(int x = 0; x < small_w; x++)

{

// Get a pixel

auto [r, g, b, a] = inputs.image.get(

std::floor(x * downscale_factor), std::floor(y * downscale_factor));

// (Dirtily) Take the luminance and compute its contrast

double contrasted = std::pow((r + g + b) / (3. * 255.), 4.);

// (Dirtily) Posterize

uint8_t col

= std::clamp(uint8_t(contrasted * 8) * (255 / 8.) * inputs.gain, 0., 255.);

// Update the output texture

outputs.image.set(x, y, col, col, col, 255);

}

}

// Call this when the texture changed

outputs.image.upload();

}

};

}