From 79c190b9d8f382e9e553d42c9361a85e588ff36f Mon Sep 17 00:00:00 2001
From: Garima <garima19802003@gmail.com>
Date: Thu, 4 Jul 2024 21:33:30 +0530
Subject: [PATCH] Solves issue #7059

---
 src/core/environment.js | 42 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/src/core/environment.js b/src/core/environment.js
index cf4444bc65..75ed27c53e 100644
--- a/src/core/environment.js
+++ b/src/core/environment.js
@@ -1078,6 +1078,48 @@ function exitFullscreen() {
   }
 }
 
+
+/**
+ * Converts 3D world coordinates to 2D screen coordinates.
+ *
+ * This function takes a 3D vector and converts its coordinates
+ * from the world space to screen space. This is useful for placing
+ * 2D elements in a 3D scene or for determining the screen position
+ * of 3D objects.
+ *
+ * @method worldToScreen
+ * @param {p5.Vector} worldPosition The 3D coordinates in the world space.
+ * @return {p5.Vector} A vector containing the 2D screen coordinates.
+ * @example
+ * <div>
+ * <code>
+ * </code>
+ * </div>
+ * @alt
+ * A 3D scene with a rotating box and a red ellipse at the screen coordinates of the world origin.
+ */
+p5.prototype.worldToScreen = function(worldPosition) {
+  const renderer = this._renderer;
+  if (renderer.drawingContext instanceof CanvasRenderingContext2D) {
+    // Handle 2D context
+    const transformMatrix = new DOMMatrix()
+      .scale(1 / pixelDensity())
+      .multiply(renderer.drawingContext.getTransform());
+    const screenCoordinates = transformMatrix.transformPoint(
+      new DOMPoint(worldPosition.x, worldPosition.y));
+    return createVector(screenCoordinates.x, screenCoordinates.y);
+  } else{
+    // Handle WebGL context
+    const cameraCoordinates = renderer.uMVMatrix.multiplyPoint(worldPosition);
+    const normalizedDeviceCoordinates =
+    renderer.uPMatrix.multiplyAndNormalizePoint(cameraCoordinates);
+    const screenX = (0.5 + 0.5 * normalizedDeviceCoordinates.x) * this.width;
+    const screenY = (0.5 - 0.5 * normalizedDeviceCoordinates.y) * this.height;
+    const screenZ = (0.5 + 0.5 * normalizedDeviceCoordinates.z);
+    return createVector(screenX, screenY, screenZ);
+  }
+};
+
 /**
  * Returns the sketch's current
  * <a href="https://developer.mozilla.org/en-US/docs/Learn/Common_questions/Web_mechanics/What_is_a_URL" target="_blank">URL</a>