From eb8a896865a6f3dbb5e3680c43ae408e29176ae4 Mon Sep 17 00:00:00 2001
From: lamp
Date: Fri, 29 Dec 2023 23:32:34 +0000
Subject: initial dsw_mixin stuff

---
 src/perlin.rs | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

(limited to 'src/perlin.rs')

diff --git a/src/perlin.rs b/src/perlin.rs
index 393582b..0b29f48 100644
--- a/src/perlin.rs
+++ b/src/perlin.rs
@@ -1,7 +1,53 @@
+use std::eprintln;
+
 use crate::vec3::{Vec3, Point3};
 
 const POINT_COUNT: usize = 256;
 
+// Mix-in images are necessarily monochrome, so each data entry is a pixel.
+pub struct MixInImage {
+    width: usize,
+    height: usize,
+    data: Vec<f64>,
+}
+
+impl MixInImage {
+    pub fn from_bmp(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;
+        // assuming 3 channels, all of which are equal
+        let data = bmp_data[(data_position as usize)..bmp_data.len()].iter().skip(2).step_by(3).map(|x| *x as f64 / 255.0).collect();
+        Self {
+            width,
+            height,
+            data,
+        }
+    }
+
+    pub fn get(&self, point: &Point3) -> &f64 {
+        let disc_x = ((point.x * self.width as f64) % self.width as f64) as usize;
+        let disc_y = ((point.y * self.height as f64) % self.height as f64) as usize;
+        self.data.get((disc_y * self.width) + disc_x).unwrap()
+    }
+}
+
 pub struct Perlin {
     ranvec: Vec<Vec3>,
     perm_x: Vec<usize>,
@@ -50,6 +96,25 @@ impl Perlin {
         accum.abs()
     }
 
+    
+    pub fn turb_dsw_mixin(&self, point: &Point3, depth: u32, factor: f64, mixin: &MixInImage, mixin_factor: f64, mixin_strength: f64) -> f64 {
+        let mut accum = 0.0;
+        let mut temp_point = point.clone();
+        let mut mixin_point = point.clone();
+        let mut weight = 1.0;
+
+        for _ in 0..depth {
+            accum += weight * (1.0 - mixin_strength) * self.noise(&temp_point);
+            temp_point *= 2.0;
+            let diff = temp_point.xy_diff(&|p: &Vec3| -> f64 {weight * self.noise(p)});
+            temp_point += &diff * factor;
+            mixin_point += &diff * mixin_factor;
+            accum += weight * mixin_strength * mixin.get(&mixin_point);
+            weight *= 0.5;
+        }
+        accum.abs()
+    }
+
     pub fn noise(&self, point: &Point3) -> f64 {
         let u = point.x - point.x.floor();
         let v = point.y - point.y.floor();
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