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use super::Texture;
use crate::{vec3::Color, vec3::Point3};
// assume 24 bit depth
const BYTES_PER_PIXEL: usize = 3;
pub struct ImageTexture {
data: Vec<u8>,
width: usize,
height: usize,
bytes_per_scanline: usize,
}
impl ImageTexture {
pub fn from_bmp_data(bmp_data: &Vec<u8>) -> Self {
let data_position = u32::from_le_bytes([
bmp_data[0x0A],
bmp_data[0x0B],
bmp_data[0x0C],
bmp_data[0x0D],
]);
// assuming windows BITMAPINFOHEADER, these are i32
let width = i32::from_le_bytes([
bmp_data[0x12],
bmp_data[0x13],
bmp_data[0x14],
bmp_data[0x15],
]) as usize;
let height = i32::from_le_bytes([
bmp_data[0x16],
bmp_data[0x17],
bmp_data[0x18],
bmp_data[0x19],
]) as usize;
Self {
data: bmp_data[(data_position as usize)..bmp_data.len()].to_vec(),
height,
width,
bytes_per_scanline: BYTES_PER_PIXEL * width,
}
}
}
impl Texture for ImageTexture {
fn value(&self, u: f64, v: f64, _: &Point3) -> Color {
let u = u.clamp(0.0, 1.0);
// This is a deviation from the book, where v gets flipped.
// This is probably because the BMP loader loads in stuff upside down.
//let v = 1.0 - v.clamp(0.0, 1.0);
let v = v.clamp(0.0, 1.0);
let mut i = (u * self.width as f64) as usize;
let mut j = (v * self.height as f64) as usize;
if i >= self.width { i = self.width - 1 };
if j >= self.height { j = self.height - 1 };
let color_scale = 1.0 / 255.0;
let pixel = j * self.bytes_per_scanline + i * BYTES_PER_PIXEL;
Color {
x: color_scale * *self.data.get(pixel + 2).unwrap() as f64,
y: color_scale * *self.data.get(pixel + 1).unwrap() as f64,
z: color_scale * *self.data.get(pixel).unwrap() as f64,
}
}
}
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