From 0b94f1f488b8d8ec717be35171a4b4997d49419d Mon Sep 17 00:00:00 2001
From: Shinmera <shinmera@tymoon.eu>
Date: Thu, 21 Mar 2019 14:35:29 +0100
Subject: [PATCH] Create tangent vectors for assimp models

---
 formats/assimp.lisp | 12 ++++++++----
 geometry.lisp       | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/formats/assimp.lisp b/formats/assimp.lisp
index 81db518e..ba6f413b 100644
--- a/formats/assimp.lisp
+++ b/formats/assimp.lisp
@@ -7,16 +7,19 @@
 (in-package #:org.shirakumo.fraf.trial)
 
 (defmethod classimp->mesh (source)
-  (let* ((mesh (make-instance 'vertex-mesh :vertex-type 'basic-vertex
+  (let* ((mesh (make-instance 'vertex-mesh :vertex-type 'basic+-vertex
                                            :face-length (classimp:primitive-types source)))
          (verts (vertices mesh))
          (faces (faces mesh)))
     (loop for location across (classimp:vertices source)
           for normal across (classimp:normals source)
           for uv across (aref (classimp:texture-coords source) 0)
-          for vertex = (make-instance 'basic-vertex :location (vec-from-vector location)
-                                                    :normal (vec-from-vector normal)
-                                                    :uv (vec2 (aref uv 0) (aref uv 1)))
+          for tangent across (classimp:tangents source)
+          for vertex = (make-instance 'basic+-vertex
+                                      :location (vec-from-vector location)
+                                      :normal (vec-from-vector normal)
+                                      :uv (vec2 (aref uv 0) (aref uv 1))
+                                      :tangent (vec-from-vector tangent))
           do (vector-push-extend vertex verts))
     (loop for face across (classimp:faces source)
           do (loop for index across face
@@ -28,6 +31,7 @@
          (scene (classimp:import-into-lisp file :processing-flags '(:ai-process-triangulate
                                                                     :ai-process-flip-u-vs
                                                                     :ai-process-fix-infacing-normals
+                                                                    :ai-process-calc-tangent-space
                                                                     ;; FIXME: should scene-graph sometime
                                                                     :ai-process-pre-transform-vertices)))
          (meshes (map 'vector #'classimp->mesh (classimp:meshes scene))))
diff --git a/geometry.lisp b/geometry.lisp
index 1fc22c8b..392796fe 100644
--- a/geometry.lisp
+++ b/geometry.lisp
@@ -165,9 +165,27 @@
 (defmethod fill-vertex-attribute ((vertex colored-vertex) (attribute (eql 'color)) data offset)
   (fill-vector-data (color vertex) 'vec4 data offset))
 
+(defclass tangent-vertex (vertex)
+  ((tangent :initform (vec 0 0 0) :initarg :tangent :accessor tangent :type vec3)))
+
+(defmethod vertex= and ((a tangent-vertex) (b tangent-vertex))
+  (v= (tangent a) (tangent b)))
+
+(defmethod vertex-attribute-size ((vertex tangent-vertex) (attribute (eql 'tangent)))
+  3)
+
+(defmethod vertex-attributes append ((vertex tangent-vertex))
+  '(tangent))
+
+(defmethod fill-vertex-attribute ((vertex tangent-vertex) (attribute (eql 'tangent)) data offset)
+  (fill-vector-data (tangent vertex) 'vec3 data offset))
+
 (defclass basic-vertex (normal-vertex textured-vertex)
   ())
 
+(defclass basic+-vertex (tangent-vertex normal-vertex textured-vertex)
+  ())
+
 ;;;; Translation
 
 (defmethod update-instance-for-different-class ((mesh vertex-mesh) (array vertex-array) &key (data-usage :static-draw) (attributes T))