[orx-mesh, orx-mesh-generator, orx-obj-loader] Add decal and tangent tools

2024-09-25 09:51:46 +02:00
parent fb3bb6f7a6
commit e016891b1d
28 changed files with 1072 additions and 82 deletions
--- a/orx-mesh-generators/src/commonMain/kotlin/tangents/MeshDataTangents.kt
+++ b/orx-mesh-generators/src/commonMain/kotlin/tangents/MeshDataTangents.kt
@@ -0,0 +1,94 @@
+package org.openrndr.extra.meshgenerators.tangents
+
+import org.openrndr.extra.mesh.*
+import org.openrndr.math.Vector3
+
+/**
+ * Estimate tangents from normals and texture coordinates
+ * https://terathon.com/blog/tangent-space.html
+ */
+fun IMeshData.estimateTangents(): MeshData {
+    require(vertexData.textureCoords.isNotEmpty()) {
+        "need texture coordinates to estimate tangents"
+    }
+    require(isTriangular()) {
+
+    }
+
+    val normals = MutableList(vertexData.positions.size) { Vector3.ZERO }
+
+    val tan1 = MutableList(vertexData.positions.size) { Vector3.ZERO }
+    val tan2 = MutableList(vertexData.positions.size) { Vector3.ZERO }
+    for (polygon in polygons) {
+        val v1 = vertexData.positions[polygon.positions[0]]
+        val v2 = vertexData.positions[polygon.positions[1]]
+        val v3 = vertexData.positions[polygon.positions[2]]
+
+        val w1 = vertexData.textureCoords[polygon.textureCoords[0]]
+        val w2 = vertexData.textureCoords[polygon.textureCoords[1]]
+        val w3 = vertexData.textureCoords[polygon.textureCoords[2]]
+
+        val x1 = (v2.x - v1.x)
+        val x2 = (v3.x - v1.x)
+        val y1 = (v2.y - v1.y)
+        val y2 = (v3.y - v1.y)
+        val z1 = (v2.z - v1.z)
+        val z2 = (v3.z - v1.z)
+
+        val s1 = (w2.x - w1.x)
+        val s2 = (w3.x - w1.x)
+        val t1 = (w2.y - w1.y)
+        val t2 = (w3.y - w1.y)
+
+        var det = s1 * t2 - s2 * t1
+        if (det == 0.0) det = 1.0
+        val r = 1.0/ (det)
+        val sdir = Vector3(
+            (t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r,
+            (t2 * z1 - t1 * z2) * r
+        ).normalized
+        val tdir = Vector3(
+            (s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r,
+            (s1 * z2 - s2 * z1) * r
+        ).normalized
+
+        tan1[polygon.positions[0]] += sdir
+        tan1[polygon.positions[1]] += sdir
+        tan1[polygon.positions[2]] += sdir
+
+        tan2[polygon.positions[0]] += tdir
+        tan2[polygon.positions[1]] += tdir
+        tan2[polygon.positions[2]] += tdir
+
+        normals[polygon.positions[0]] += vertexData.normals[polygon.normals[0]]
+        normals[polygon.positions[1]] += vertexData.normals[polygon.normals[1]]
+        normals[polygon.positions[2]] += vertexData.normals[polygon.normals[2]]
+
+    }
+
+    for (a in 0 until vertexData.positions.size) {
+        normals[a] = normals[a].normalized
+        tan1[a] = tan1[a].normalized
+        tan2[a] = tan2[a].normalized
+
+        val t = tan1[a]
+        val n = normals[a]
+
+        tan1[a] = (t - n * n.dot(t)).normalized
+        val w = if ((n.cross(t)).dot(tan2[a]) < 0.0f) -1.0 else 1.0
+        tan2[a] = n.cross((t)).normalized * w
+    }
+
+    return MeshData(VertexData(vertexData.positions, vertexData.textureCoords, vertexData.colors, normals, tan1, tan2),
+        polygons = polygons.map {
+            IndexedPolygon(
+                it.positions,
+                it.textureCoords,
+                it.colors,
+                normals = it.positions,
+                tangents = it.positions,
+                bitangents = it.positions
+            )
+        }
+    )
+}