From 78ddaff5855bf8446adef9e18eb0d7b7ddcee52a Mon Sep 17 00:00:00 2001
From: lamp
Date: Sun, 5 Mar 2023 21:45:56 +0000
Subject: init

---
 src/texture/image_texture.rs | 63 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 src/texture/image_texture.rs

(limited to 'src/texture/image_texture.rs')

diff --git a/src/texture/image_texture.rs b/src/texture/image_texture.rs
new file mode 100644
index 0000000..763c3f0
--- /dev/null
+++ b/src/texture/image_texture.rs
@@ -0,0 +1,63 @@
+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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