Add getModelViewPosition function

src/shader-chunks/shaders/depth-utils-pars.frag

@@ -43,23 +43,38 @@ float readDepth(sampler2D depthBuffer, const in vec2 uv, const in float near, co
  * @param depth - The depth value.
  * @param viewZ - The viewZ value.
  * @param projectionMatrix - The projection matrix.
- * @param inverseProjectionMatrix - The inverse projection matrix.
+ * @param projectionMatrixInverse - The inverse projection matrix.
  * @return The view position.
  */
 
 vec3 getViewPosition(const in vec2 screenPosition, const in float depth, const in float viewZ,
-	const in mat4 projectionMatrix, const in mat4 inverseProjectionMatrix) {
+	const in mat4 projectionMatrix, const in mat4 projectionMatrixInverse) {
 
 	vec4 clipPosition = vec4(vec3(screenPosition, depth) * 2.0 - 1.0, 1.0);
 
 	// Unoptimized version:
-	// vec4 viewPosition = inverseProjectionMatrix * clipPosition;
+	// vec4 viewPosition = projectionMatrixInverse * clipPosition;
 	// viewPosition /= viewPosition.w; // Unproject.
 	// return viewPosition.xyz;
 
 	float clipW = projectionMatrix[2][3] * viewZ + projectionMatrix[3][3];
 	clipPosition *= clipW; // Unproject.
 
-	return (inverseProjectionMatrix * clipPosition).xyz;
+	return (projectionMatrixInverse * clipPosition).xyz;
+
+}
+
+/**
+ * Calculates the model view position based on a given view position and view matrix.
+ *
+ * @param viewPosition - The view position.
+ * @param viewMatrix - The inverse camera transformation matrix.
+ * @return The model view position.
+ */
+
+vec3 getModelViewPosition(const in vec3 viewPosition, const in mat4 viewMatrix) {
+
+	vec4 mvPosition = viewMatrix * vec4(viewPosition, 1.0);
+	return -mvPosition.xyz;
 
 }