adjust examples to y-axis-flip

2025-10-19 14:19:17 +02:00
parent 64bd8ee530
commit 346a4fd720
5 changed files with 121 additions and 9 deletions
@@ -0,0 +1,114 @@
+//! Cartesian coordinate system example
+//!
+//! This example draws a cartesian coordinate system with X and Y axes,
+//! labeled axis endpoints, and 4 labeled points (one in each quadrant).
+
+use macroquad::prelude::*;
+use turtle_lib::*;
+
+#[turtle_main("Cartesian Axes")]
+fn draw(turtle: &mut TurtlePlan) {
+    const AXIS_LENGTH: f32 = 250.0;
+    const GRID_STEP: f32 = 50.0;
+    const FONT_SIZE: i32 = 16;
+    const SMALL_FONT: i32 = 24;
+
+    // Draw coordinate system center and axes
+    turtle
+        .reset()
+        .set_speed(1100)
+        .pen_up()
+        .go_to(vec2(0.0, 0.0))
+        .pen_down();
+
+    // Draw X axis (horizontal)
+    turtle.set_pen_color(macroquad::prelude::BLACK);
+    turtle.set_pen_width(2.0);
+    turtle.pen_up().go_to(vec2(-AXIS_LENGTH, 0.0)).pen_down();
+    turtle.forward(2.0 * AXIS_LENGTH);
+
+    // Draw Y axis (vertical)
+    turtle.pen_up().go_to(vec2(0.0, -AXIS_LENGTH)).pen_down();
+    turtle.set_heading(90.0);
+    turtle.forward(2.0 * AXIS_LENGTH);
+
+    // Draw axis tick marks (major and minor)
+    turtle.set_pen_width(1.0);
+    const MINOR_STEP: f32 = GRID_STEP / 10.0; // 1/10th markers
+
+    let mut pos = -AXIS_LENGTH;
+    while pos <= AXIS_LENGTH {
+        if (pos - 0.0).abs() > 1.0 {
+            // Skip origin
+            // Determine if this is a major or minor tick
+            let is_major = (pos / GRID_STEP).abs().fract() < 0.01;
+            let tick_length = if is_major { 10.0 } else { 5.0 };
+
+            // X axis tick
+            turtle
+                .pen_up()
+                .set_pen_width(tick_length / 5.0)
+                .go_to(vec2(pos, -tick_length / 2.0))
+                .pen_down()
+                .set_heading(90.0)
+                .forward(tick_length);
+
+            // Y axis tick
+            turtle
+                .pen_up()
+                .go_to(vec2(-tick_length / 2.0, pos))
+                .set_pen_width(tick_length / 5.0)
+                .pen_down()
+                .set_heading(0.0)
+                .forward(tick_length);
+        }
+        pos += MINOR_STEP;
+    }
+
+    // Label axes
+    turtle
+        .pen_up()
+        .go_to(vec2(AXIS_LENGTH + 20.0, 0.0))
+        .set_heading(0.0)
+        .write_text("X", FONT_SIZE);
+
+    turtle
+        .pen_up()
+        .go_to(vec2(0.0, AXIS_LENGTH + 20.0))
+        .set_heading(0.0)
+        .write_text("Y", FONT_SIZE);
+
+    // Draw and label 4 points (one per quadrant)
+    let points = vec![
+        (vec2(120.0, 100.0), "A(2|1)"),
+        (vec2(-120.0, 100.0), "B(-2|1)"),
+        (vec2(-120.0, -100.0), "C(-2|-1)"),
+        (vec2(120.0, -100.0), "D(2|-1)"),
+    ];
+
+    for (position, label) in points {
+        // Draw point as small circle
+        turtle
+            .pen_up()
+            .go_to(position)
+            .set_pen_color(macroquad::prelude::RED)
+            .set_pen_width(7.0)
+            .pen_down()
+            .forward(1.0); // Just a small mark
+
+        // Add label
+        let label_offset = vec2(label.len() as f32 * 2.5, 0.0);
+        turtle
+            .pen_up()
+            .go_to(position - label_offset)
+            .set_heading(0.0)
+            .write_text(label, SMALL_FONT);
+    }
+
+    // Label origin
+    turtle
+        .pen_up()
+        .go_to(vec2(-30.0, -20.0))
+        .set_heading(0.0)
+        .write_text("O", FONT_SIZE);
+}