Flip cursor y coordinate.

Author: bcata6

shaders/src/lib.rs

@@ -60,22 +60,22 @@ pub fn fs(constants: &ShaderConstants, mut frag_coord: Vec2) -> Vec4 {
         0.0,
     );
     let time = constants.time;
-    let mouse = vec4(
+    let mut mouse = vec4(
         constants.drag_end_x / COLS as f32,
         constants.drag_end_y / ROWS as f32,
-        constants.drag_start_x / COLS as f32
-            * if constants.mouse_left_pressed {
-                1.0
-            } else {
-                -1.0
-            },
-        constants.drag_start_y / ROWS as f32
-            * if constants.mouse_left_clicked {
-                1.0
-            } else {
-                -1.0
-            },
+        constants.drag_start_x / COLS as f32,
+        constants.drag_start_y / ROWS as f32,
     );
+    if mouse != Vec4::zero() {
+        mouse.y = resolution.y - mouse.y;
+        mouse.w = resolution.y - mouse.w;
+    }
+    if !constants.mouse_left_pressed {
+        mouse.z *= -1.0;
+    }
+    if !constants.mouse_left_clicked {
+        mouse.w *= -1.0;
+    }
 
     let col = (frag_coord.x / resolution.x) as usize;
     let row = (frag_coord.y / resolution.y) as usize;