Attempt to fix (6)

2 files changed, 49 insertions, 8 deletions

diff --git a/TODO.md b/TODO.md
index d002a6f..482a063 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,4 +1,4 @@
-Keyboard Input
+(1) Keyboard Input
 	Nov 30th:
 	the main input method right now is spinning the two thumbsticks on
 	some kind of game controller, but you can't spin a keyboard key.
@@ -19,14 +19,29 @@ Keyboard Input
 	be: `VerticalGallop jkl;`. reversing those characters could allow you
 	to invert the direction of the gallop, but that should also be an option.
 
-Images save as GIF and PNG
+	Dec 7th:
+	this is pretty clunky. perhaps the tuning cannot fix it. we should try
+	and see if just advancing the cursor on keypress feels alright. the
+	direction thing would need work, though. "on keypress" to mean the
+	entire press not while down. I want a press to be an action alone and
+	not some kind of "smooth draw". although i guess that's what the
+	etch-a-sketch would be like? lots to think about.
+
+(2) Mouse Input
+	this would be cute. Two mice required :)
+
+	one scroll wheel for each degree of freedom. we can have a little
+	sub-window where you can click to identify the mice, "vertical" and
+	"horizontal", and then perhaps a setting to switch them.
+
+(3) Images save as GIF and PNG
 	gif can have a palette of 4 and so can the png. The png might be able
 	to have a depth of 2-bits per pixel which is exciting.
 
 	images should be saved in the underlying resolution and not be dpi
 	scaled. images should not include the stylus.
 
-Clearing should be gradual
+(4) Clearing should be gradual
 	It should require multiple button presses, to imitate shaking a thing,
 	and with each shake the existing lines should get some fixed amount
 	closer to the background colour. maybe they gain 10% of the difference
@@ -35,9 +50,26 @@ Clearing should be gradual
 	It would be cute if the screen did a side-to-side animation on each
 	press as well.
 
+(5) Crash when you try to go below the bottom
+	If you're moving down and you hit the bottom edge, we crash.
+
+(6) Lines with a positive slope draw wrong
+	When you're diagonaling right and up, the line draws almost-inverted
+	and comes out as right and down, but it's more than that. Seemingly,
+	the start and end of the slop-line draw with swapped Y coordinates.
+
+	image.rs:98
+	this just swaps the problem. i think what we need to do is figure
+	out when it gets mad, possibly all the time when the starting Y is
+	lower in the image (so higher Y value) than the ending position.
+	And then we should special-case that. Or attempt to use a "real"
+	line drawing algorithm. Draw larger-than-a-pixel-squares at every
+	point is certainly an algorithm, but probably not the most efficient
+	one we can use. Modified brashman's for thick lines?
+
 ==== DONE? ====
 
-Reduce memory usage with profiling
+(7) Reduce memory usage with profiling
 	resources:
 	- A blog post from the rust-analyzer team on memory profiling (Dec. 2020)
 	  https://rust-analyzer.github.io/blog/2020/12/04/measuring-memory-usage-in-rust.html
diff --git a/src/image.rs b/src/image.rs
index c1e67db..177eff2 100644
--- a/src/image.rs
+++ b/src/image.rs
@@ -88,12 +88,21 @@ impl Image {
 	/// draws a rect of the specified width at that location.
 	pub fn line(&mut self, p1: Vec2<u32>, p2: Vec2<u32>, width: u32, clr: Color) {
 		let start_x = p1.x.min(p2.x) as f32;
-		let start_y = p1.y.min(p2.y) as f32;
+		let mut start_y = p1.y.min(p2.y) as f32;
 		let end_x = p1.x.max(p2.x) as f32;
-		let end_y = p1.y.max(p2.y) as f32;
+		let mut end_y = p1.y.max(p2.y) as f32;
+
+		if start_y < end_y && start_x < end_x {
+			// this just swaps the problem.
+			//FIXME: genny- 2024-12
+			let temp_y = start_y;
+			start_y = end_y;
+			end_y = temp_y;
+		}
 
-		tracing::trace!("start_x = {start_x} / end_x = {end_x}");
-		tracing::trace!("start_y = {start_y} / end_y = {end_y}");
+		tracing::trace!("LINE");
+		tracing::trace!("\tstart_x = {start_x} / end_x = {end_x}");
+		tracing::trace!("\tstart_y = {start_y} / end_y = {end_y}");
 
 		let dx = end_x - start_x;
 		let dy = end_y - start_y;