take screen ratio into account

src/plotter2d.rs

@@ -21,7 +21,9 @@ impl Plotter2d {
             include_str!("../assets/shaders/color.vert"),
             include_str!("../assets/shaders/color.frag")).unwrap();
 
-        let camera = Camera {position: (0.0, 0.0), size: 10.0};
+        let start_x_range = 10.0;
+        let camera_size: (f32, f32) = (start_x_range, start_x_range * screen_size.1 as f32 / screen_size.0 as f32);
+        let camera = Camera {position: (0.0, 0.0), size: camera_size };
         let plot = Plot::new(gl, &expression, screen_size.0 as u32, &camera);
 
         Plotter2d {
@@ -46,13 +48,14 @@ impl plotter::Plotter for Plotter2d {
     }
 
     fn zoom(&mut self, delta: f32) {
-        self.camera.size *= (1.03 as f32).powf(delta);
+        self.camera.size.0 *= (1.03 as f32).powf(delta);
+        self.camera.size.1 *= (1.03 as f32).powf(delta);
         self.update_view();
     }
 
     fn translate(&mut self, delta_x: f32, delta_y: f32) {
-        self.camera.position.0 += delta_x * self.camera.size / self.screen_size.0 as f32;
-        self.camera.position.1 += delta_y * self.camera.size / self.screen_size.1 as f32;
+        self.camera.position.0 += delta_x * self.camera.size.0 / self.screen_size.0 as f32;
+        self.camera.position.1 += delta_y * self.camera.size.1 / self.screen_size.1 as f32;
         self.update_view();
     }
 
@@ -65,14 +68,14 @@ impl plotter::Plotter for Plotter2d {
 
 struct Camera {
     position: (f32, f32),
-    size: f32
+    size: (f32, f32)
 }
 
 impl Camera { 
     // project a point to normalized coordinates [-1,1]
     fn to_normalized_coordinates(&self, point: (f32, f32)) -> (f32, f32) {
-        let x_proj = 2.0*(point.0 - self.position.0)/self.size;
-        let y_proj = 2.0*(point.1 - self.position.1)/self.size;
+        let x_proj = 2.0*(point.0 - self.position.0)/self.size.0;
+        let y_proj = 2.0*(point.1 - self.position.1)/self.size.1;
         (x_proj, y_proj)
     }
 }
@@ -125,10 +128,10 @@ impl Plot {
     fn generate_positions(expression: &Expression<IntervalSet<f64>>, resolution: u32, camera: &Camera) -> Vec<f32> {
 
         let display_info = plot_generator2d::Rectangle {
-            x_start: (camera.position.0 - camera.size/2.0) as f64,
-            x_end: (camera.position.0 + camera.size/2.0) as f64,
-            y_start: (camera.position.1 - camera.size/2.0) as f64,
-            y_end: (camera.position.1 + camera.size/2.0) as f64,
+            x_start: (camera.position.0 - camera.size.0 / 2.0) as f64,
+            x_end: (camera.position.0 + camera.size.0 / 2.0) as f64,
+            y_start: (camera.position.1 - camera.size.1 / 2.0) as f64,
+            y_end: (camera.position.1 + camera.size.1 / 2.0) as f64,
         };
 
         let rectangles = plot_generator2d::generate_2dplot_implicit(expression, display_info, resolution);