some more examples

turtle-lib/examples/geometric_art.rs

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+//! Creates colorful geometric art with randomly colored triangles.
+//!
+//! Ported from the turtle crate example.
+
+use turtle_lib::*;
+use macroquad::prelude::rand;
+
+// Parameters to play around with for changing the character of the drawing
+const WIDTH: f32 = 800.0;
+const HEIGHT: f32 = 600.0;
+const ROW_COUNT: u32 = 3;
+const COL_COUNT: u32 = 4;
+const COLOR_COUNT: usize = 7;
+
+/// Generate a random color
+fn random_color() -> Color {
+    Color {
+        r: rand::gen_range(0.0, 1.0),
+        g: rand::gen_range(0.0, 1.0),
+        b: rand::gen_range(0.0, 1.0),
+        a: 1.0,
+    }
+}
+
+#[turtle_main("Geometric Art")]
+fn draw(turtle: &mut TurtlePlan) {
+    // Calculate height and width of the triangles
+    let row_height = HEIGHT / ROW_COUNT as f32;
+    let col_width = WIDTH / COL_COUNT as f32;
+
+    // Prepare a set of random colors to randomly choose from when drawing
+    let colors: Vec<Color> = (0..COLOR_COUNT).map(|_| random_color()).collect();
+
+    // Move turtle to the upper left corner of the drawing
+    let x_start = -WIDTH / 2.0;
+    let y_start = HEIGHT / 2.0;
+
+    turtle.pen_up().go_to(vec2(x_start, y_start)).pen_down();
+
+    // Draw all rows
+    for _ in 0..ROW_COUNT {
+        // Create an endless loop over the angles of 90 and 270 degrees
+        // (corresponds to moving right and left, respectively)
+        let mut angle_iter = [90.0, 270.0].iter().cycle();
+
+        // Create triangles from left to right
+        for _ in 0..COL_COUNT {
+            let angle = *angle_iter.next().unwrap();
+            draw_triangle(turtle, angle, col_width, row_height, &colors);
+        }
+
+        // Skip one angle so that we have the correct angle when turning around
+        angle_iter.next();
+
+        // Fill in triangles from right to left to complete the row
+        for _ in 0..COL_COUNT {
+            let angle = *angle_iter.next().unwrap();
+            draw_triangle(turtle, angle, col_width, row_height, &colors);
+        }
+
+        // Reset position to prepare for the next row
+        turtle.right(180.0).forward(row_height).left(180.0);
+    }
+}
+
+/// Draw a single triangle by drawing two sides and filling them with a random color
+/// which creates the third side of the triangle along the way.
+fn draw_triangle(
+    turtle: &mut TurtlePlan,
+    angle: f32,
+    col_width: f32,
+    row_height: f32,
+    colors: &[Color],
+) {
+    // Choose a random color
+    let color_index = rand::gen_range(0, colors.len());
+    let color = colors[color_index];
+
+    turtle
+        .set_fill_color(color)
+        .begin_fill()
+        .right(angle)
+        .forward(col_width)
+        .right(angle)
+        .forward(row_height)
+        .end_fill();
+}