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use alloc::vec;
use alloc::vec::Vec;
use crate::ppu::Ppu;
use serde::{Deserialize, Serialize};
use core::f64::consts::PI;
use lazy_static::lazy_static;
use num_traits::Float;
#[derive(Default, Debug, Copy, Clone, Eq, PartialEq, Hash, Serialize, Deserialize)]
#[must_use]
pub enum VideoFilter {
Pixellate,
#[default]
Ntsc,
}
impl VideoFilter {
pub const fn as_slice() -> &'static [Self] {
&[Self::Pixellate, Self::Ntsc]
}
}
impl AsRef<str> for VideoFilter {
fn as_ref(&self) -> &str {
match self {
Self::Pixellate => "Pixellate",
Self::Ntsc => "NTSC",
}
}
}
impl From<usize> for VideoFilter {
fn from(value: usize) -> Self {
if value == 1 {
Self::Ntsc
} else {
Self::Pixellate
}
}
}
#[derive(Clone)]
#[must_use]
pub struct Video {
filter: VideoFilter,
output: Vec<u8>,
}
impl Default for Video {
fn default() -> Self {
Self::new()
}
}
impl Video {
pub fn new() -> Self {
let mut output = vec![0x00; 4 * Ppu::SIZE];
// Force alpha to 255.
for p in output.iter_mut().skip(3).step_by(4) {
*p = 255;
}
Self {
filter: VideoFilter::default(),
output,
}
}
#[inline]
pub const fn filter(&self) -> VideoFilter {
self.filter
}
#[inline]
pub fn set_filter(&mut self, filter: VideoFilter) {
self.filter = filter;
}
// Returns a fully rendered frame of RENDER_SIZE RGB colors
pub fn apply_filter(&mut self, buffer: &[u16], frame_number: u32) {
match self.filter {
VideoFilter::Pixellate => self.decode_buffer(buffer),
VideoFilter::Ntsc => self.apply_ntsc_filter(buffer, frame_number),
}
}
#[inline]
#[must_use]
pub fn output(&self) -> &[u8] {
&self.output
}
pub fn decode_buffer(&mut self, buffer: &[u16]) {
assert!(buffer.len() * 4 == self.output.len());
for (pixel, colors) in buffer.iter().zip(self.output.chunks_exact_mut(4)) {
assert!(colors.len() > 2);
let (red, green, blue) = Ppu::system_palette(*pixel);
colors[0] = red;
colors[1] = green;
colors[2] = blue;
// Alpha should always be 255
}
}
// Amazing implementation Bisqwit! Much faster than my original, but boy what a pain
// to translate it to Rust
// Source: https://bisqwit.iki.fi/jutut/kuvat/programming_examples/nesemu1/nesemu1.cc
// http://wiki.nesdev.com/w/index.php/NTSC_video
pub fn apply_ntsc_filter(&mut self, buffer: &[u16], frame_number: u32) {
assert!(buffer.len() * 4 == self.output.len());
let mut prev_pixel = 0;
for (idx, (pixel, colors)) in buffer
.iter()
.zip(self.output.chunks_exact_mut(4))
.enumerate()
{
let x = idx % 256;
let color = if x == 0 {
// Remove pixel 0 artifact from not having a valid previous pixel
0
} else {
let y = idx / 256;
let even_phase = if frame_number & 0x01 == 0x01 { 0 } else { 1 };
let phase = (2 + y * 341 + x + even_phase) % 3;
NTSC_PALETTE
[phase + ((prev_pixel & 0x3F) as usize) * 3 + (*pixel as usize) * 3 * 64]
};
prev_pixel = u32::from(*pixel);
assert!(colors.len() > 2);
colors[0] = (color >> 16 & 0xFF) as u8;
colors[1] = (color >> 8 & 0xFF) as u8;
colors[2] = (color & 0xFF) as u8;
// Alpha should always be 255
}
}
}
impl core::fmt::Debug for Video {
fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
f.debug_struct("Video")
.field("filter", &self.filter)
.field("output_len", &self.output.len())
.finish()
}
}
lazy_static! {
pub static ref NTSC_PALETTE: Vec<u32> ={
// NOTE: There's lot's to clean up here -- too many magic numbers and duplication but
// I'm afraid to touch it now that it works
// Source: https://bisqwit.iki.fi/jutut/kuvat/programming_examples/nesemu1/nesemu1.cc
// http://wiki.nesdev.com/w/index.php/NTSC_video
// Calculate the luma and chroma by emulating the relevant circuits:
const VOLTAGES: [i32; 16] = [
-6, -69, 26, -59, 29, -55, 73, -40, 68, -17, 125, 11, 68, 33, 125, 78,
];
let mut ntsc_palette = vec![0; 512 * 64 * 3];
// Helper functions for converting YIQ to RGB
let gamma = 2.0; // Assumed display gamma
let gammafix = |color: f64| {
if color <= 0.0 {
0.0
} else {
color.powf(2.2 / gamma)
}
};
let yiq_divider = f64::from(9 * 10u32.pow(6));
for palette_offset in 0..3 {
for channel in 0..3 {
for color0_offset in 0..512 {
let emphasis = color0_offset / 64;
for color1_offset in 0..64 {
let mut y = 0;
let mut i = 0;
let mut q = 0;
// 12 samples of NTSC signal constitute a color.
for sample in 0..12 {
let noise = (sample + palette_offset * 4) % 12;
// Sample either the previous or the current pixel.
// Use pixel=color0 to disable artifacts.
let pixel = if noise < 6 - channel * 2 {
color0_offset
} else {
color1_offset
};
// Decode the color index.
let chroma = pixel & 0x0F;
// Forces luma to 0, 4, 8, or 12 for easy lookup
let luma = if chroma < 0x0E { (pixel / 4) & 12 } else { 4 };
// NES NTSC modulator (square wave between up to four voltage levels):
let limit = if (chroma + 8 + sample) % 12 < 6 {
12
} else {
0
};
let high = if chroma > limit { 1 } else { 0 };
let emp_effect = if (152_278 >> (sample / 2 * 3)) & emphasis > 0 {
0
} else {
2
};
let level = 40 + VOLTAGES[high + emp_effect + luma];
// Ideal TV NTSC demodulator:
let (sin, cos) = (PI * sample as f64 / 6.0).sin_cos();
y += level;
i += level * (cos * 5909.0) as i32;
q += level * (sin * 5909.0) as i32;
}
// Store color at subpixel precision
let y = f64::from(y) / 1980.0;
let i = f64::from(i) / yiq_divider;
let q = f64::from(q) / yiq_divider;
let idx = palette_offset + color0_offset * 3 * 64 + color1_offset * 3;
match channel {
2 => {
let rgb =
255.95 * gammafix(q.mul_add(0.623_557, i.mul_add(0.946_882, y)));
ntsc_palette[idx] += 0x10000 * rgb.clamp(0.0, 255.0) as u32;
}
1 => {
let rgb =
255.95 * gammafix(q.mul_add(-0.635_691, i.mul_add(-0.274_788, y)));
ntsc_palette[idx] += 0x00100 * rgb.clamp(0.0, 255.0) as u32;
}
0 => {
let rgb =
255.95 * gammafix(q.mul_add(1.709_007, i.mul_add(-1.108_545, y)));
ntsc_palette[idx] += rgb.clamp(0.0, 255.0) as u32;
}
_ => (), // invalid channel
}
}
}
}
}
ntsc_palette
};
}