WIP: Add AccumulationBuffer

src/accumulation_buffer.rs

@@ -0,0 +1,69 @@
+use crate::image::{ImageRgbU8, ToneMapper};
+use crate::util::{Array2D, Tile};
+
+use std::ops::{Add, Mul};
+
+pub struct AccumulationBuffer<T> {
+    colour_buffer: Array2D<T>,
+    weight_buffer: Array2D<f64>,
+}
+
+impl<T> AccumulationBuffer<T>
+where
+    T: Add<T, Output = T> + Mul<f64, Output = T> + Default + Copy,
+{
+    pub fn new(width: usize, height: usize) -> AccumulationBuffer<T> {
+        let colour_buffer = Array2D::new(width, height);
+        let weight_buffer = Array2D::new(width, height);
+        AccumulationBuffer {
+            colour_buffer,
+            weight_buffer,
+        }
+    }
+
+    pub fn width(&self) -> usize {
+        self.colour_buffer.get_width()
+    }
+
+    pub fn height(&self) -> usize {
+        self.colour_buffer.get_height()
+    }
+
+    pub fn to_image_rgb_u8<Op: ToneMapper<T>>(&self, tone_mapper: &Op) -> ImageRgbU8 {
+        let mut result = ImageRgbU8::new(self.width(), self.height());
+        tone_mapper.apply_tone_mapping(&self.colour_buffer, &mut result);
+        result
+    }
+
+    pub fn update_pixel(&mut self, row: usize, column: usize, colour: &T, weight: f64) {
+        let buffer_colour = &mut self.colour_buffer[row][column];
+        let buffer_weight = &mut self.weight_buffer[row][column];
+
+        *buffer_colour = blend(buffer_colour, *buffer_weight, colour, weight);
+        *buffer_weight += weight;
+    }
+
+    pub fn update_tile(&mut self, tile: &Tile, colour: &Array2D<T>, weights: &Array2D<f64>) {
+        assert!(tile.width() == colour.get_width());
+        assert!(tile.height() == colour.get_height());
+        assert!(tile.width() == weights.get_width());
+        assert!(tile.height() == weights.get_height());
+        for i in 0..tile.height() {
+            for j in 0..tile.width() {
+                self.update_pixel(
+                    tile.start_row + i,
+                    tile.start_column + j,
+                    &colour[i][j],
+                    weights[i][j],
+                );
+            }
+        }
+    }
+}
+
+fn blend<T>(value1: &T, weight1: f64, value2: &T, weight2: f64) -> T
+where
+    T: Add<T, Output = T> + Mul<f64, Output = T> + Copy,
+{
+    (*value1 * weight1 + *value2 * weight2) * (1.0 / (weight1 + weight2))
+}

src/lib.rs

@@ -1,6 +1,7 @@
 #![feature(external_doc, clamp)]
 #![doc(include = "../README.md")]
 
+pub mod accumulation_buffer;
 mod camera;
 pub mod colour;
 pub mod image;