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//! Transformation module
//!
//! Useful to turn on-screen coordinates into measurements of the "real" world the map describes
//! and the other way around.
use crate::math::{Rect, Vec2};
const STANDARD_PIXELS_PER_M: f32 = 64.;
const MIN_PIXELS_PER_M: f32 = 5.;
const MAX_PIXELS_PER_M: f32 = 10_000.;
pub struct Transform {
/// The (not necessarily natural) number of pixels per m, i.e. the current scale of the map
pixels_per_m: f32,
/// The vector the entire on-screen map is moved by in pixels
translation_px: Vec2<f32>,
}
impl Transform {
/// Create a new standard transformation for the map.
pub fn new() -> Self {
Self {
pixels_per_m: STANDARD_PIXELS_PER_M,
translation_px: Vec2::new(0., 0.),
}
}
/// Convert a point that is given in meters into the corresponding point in pixels.
#[inline]
pub fn point_m_to_px(&self, point: Vec2<f32>) -> Vec2<f32> {
// Start by converting the absolute position in meters into the absolute position in
// pixels, then add the translation of the screen.
(point * self.pixels_per_m) + self.translation_px
}
/// Convert an on-screen point into an absolute point with values in meters.
#[inline]
pub fn point_px_to_m(&self, point: Vec2<f32>) -> Vec2<f32> {
// Start by subtracting the pixel translation and afterwards convert these absolute pixel
// measurements into meters.
(point - self.translation_px) / self.pixels_per_m
}
/// Convert a length given in meters into a length in pixels
#[inline]
pub fn length_m_to_px(&self, length: f32) -> f32 {
length * self.pixels_per_m
}
/// Convert a length given in pixels into a length in meters
#[inline]
pub fn length_px_to_m(&self, length: f32) -> f32 {
length / self.pixels_per_m
}
/// Convert a rectangle which has measurements in meters into one of pixels
#[inline]
pub fn rect_m_to_px(&self, rect: Rect<f32>) -> Rect<f32> {
let left_upper = self.point_m_to_px(Vec2::new(rect.x, rect.y));
Rect::new(
left_upper.x,
left_upper.y,
self.length_m_to_px(rect.w),
self.length_m_to_px(rect.h),
)
}
/// Convert a rectangle which has measurements in pixels into one of meters
#[inline]
pub fn rect_px_to_m(&self, rect: Rect<f32>) -> Rect<f32> {
let left_upper = self.point_px_to_m(Vec2::new(rect.x, rect.y));
Rect::new(
left_upper.x,
left_upper.y,
self.length_px_to_m(rect.w),
self.length_px_to_m(rect.h),
)
}
/// Attempts to zoom the pixels per meter by the amount of factor.
///
/// # Arguments
/// `factor`: A number greater than one means zooming in, a number less than one means zooming out. What happens when you try to
/// zoom with a negative factor you'll have to figure out yourself.
/// `mouse_pos_px`: Position of the mouse cursor, this time not in meters, but in screen
/// pixels. This will be used to tether zoom on that point.
pub fn try_zoom(&mut self, mouse_pos_px: Vec2<f32>, factor: f32) -> bool {
// Abort zooming when the scale would not be in the min-max-bounds anymore.
let desired_px_per_m = self.pixels_per_m * factor;
if (factor < 1. && desired_px_per_m <= MIN_PIXELS_PER_M)
|| (factor > 1. && desired_px_per_m >= MAX_PIXELS_PER_M)
{
return false;
}
// Save the absolute mouse position in meters for tethering later
let mouse_pos_m = self.point_px_to_m(mouse_pos_px);
// Make sure the desired scale stays within the bounds and in whole numbers
let desired_px_per_m = if desired_px_per_m < MIN_PIXELS_PER_M {
MIN_PIXELS_PER_M as u32 as f32
} else if desired_px_per_m > MAX_PIXELS_PER_M {
MAX_PIXELS_PER_M as u32 as f32
} else {
desired_px_per_m as u32 as f32
};
/* Adjust to the desired scale and bring the map back to its desired position according to
* the mouse pointer position.
*/
self.pixels_per_m = desired_px_per_m;
self.translation_px += mouse_pos_px - self.point_m_to_px(mouse_pos_m);
true
}
/// Move the canvas by the vector in pixels.
pub fn move_by_px(&mut self, by: Vec2<f32>) {
self.translation_px += by;
}
pub fn pixels_per_m(&self) -> f32 {
self.pixels_per_m
}
pub fn translation_px(&self) -> Vec2<f32> {
self.translation_px
}
}
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