[orx-mesh, orx-obj-loader] Separate into commonMain and jvmMain

orx-mesh/src/jvmMain/kotlin/VertexBufferExtensions.kt

@@ -0,0 +1,57 @@
+import org.openrndr.color.ColorRGBa
+import org.openrndr.draw.VertexBuffer
+import org.openrndr.extra.objloader.Polygon
+import org.openrndr.extra.objloader.objVertexFormat
+import org.openrndr.math.Vector2
+import org.openrndr.math.Vector3
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+
+
+private fun ByteBuffer.getVector3(): Vector3 {
+    val x = getFloat()
+    val y = getFloat()
+    val z = getFloat()
+    return Vector3(x.toDouble(), y.toDouble(), z.toDouble())
+}
+
+private fun ByteBuffer.getVector2(): Vector2 {
+    val x = getFloat()
+    val y = getFloat()
+    return Vector2(x.toDouble(), y.toDouble())
+}
+
+private fun ByteBuffer.getColorRGBa(): ColorRGBa {
+    val r = getFloat()
+    val g = getFloat()
+    val b = getFloat()
+    val a = getFloat()
+    return ColorRGBa(r.toDouble(), g.toDouble(), b.toDouble(), a.toDouble())
+}
+
+/**
+    Convert vertex buffer contents to a list of [Polygon] instances
+ */
+fun VertexBuffer.toPolygons(vertexCount: Int = this.vertexCount): List<Polygon> {
+    require(vertexFormat == objVertexFormat)
+    val triangleCount = vertexCount / 3
+    val buffer = ByteBuffer.allocateDirect(this.vertexCount * vertexFormat.size)
+    buffer.order(ByteOrder.nativeOrder())
+
+    val polygons = mutableListOf<Polygon>()
+    for (t in 0 until triangleCount) {
+        val positions = mutableListOf<Vector3>()
+        val normals = mutableListOf<Vector3>()
+        val textureCoordinates = mutableListOf<Vector2>()
+        val colors = mutableListOf<ColorRGBa>()
+
+        for (v in 0 until 3) {
+            positions.add(buffer.getVector3())
+            normals.add(buffer.getVector3())
+            textureCoordinates.add(buffer.getVector2())
+            colors.add(buffer.getColorRGBa())
+        }
+        polygons.add(Polygon(positions, normals, textureCoordinates, colors))
+    }
+    return polygons
+}