graphics: model: Add support for scene node transforms in glTF models.

1 files changed, 61 insertions, 20 deletions

diff --git a/chickadee/graphics/model.scm b/chickadee/graphics/model.scm
index 7abd352..b0150af 100644
--- a/chickadee/graphics/model.scm
+++ b/chickadee/graphics/model.scm
@@ -26,6 +26,7 @@
   #:use-module (chickadee base64)
   #:use-module (chickadee json)
   #:use-module (chickadee math matrix)
+  #:use-module (chickadee math quaternion)
   #:use-module (chickadee math vector)
   #:use-module (chickadee graphics buffer)
   #:use-module (chickadee graphics color)
@@ -61,29 +62,55 @@
 ;;;
 
 (define-record-type <render-state>
-  (%make-render-state renderer world-matrix view-matrix)
+  (%make-render-state renderer view-matrix
+                      matrix-stack matrix-pool)
   render-state?
   (renderer render-state-renderer)
-  (world-matrix render-state-world-matrix)
-  (view-matrix render-state-view-matrix))
+  (view-matrix render-state-view-matrix)
+  (matrix-stack render-state-matrix-stack)
+  (matrix-pool render-state-matrix-pool))
 
 (define (make-render-state renderer)
   (%make-render-state renderer
                       (make-identity-matrix4)
-                      (make-identity-matrix4)))
+                      (make-array-list)
+                      (array-list (make-identity-matrix4))))
 
-(define (render-state-reset! state)
-  (matrix4-identity! (render-state-world-matrix state))
-  (matrix4-identity! (render-state-view-matrix state)))
+(define (render-state-matrix-borrow state)
+  (let ((mpool (render-state-matrix-pool state)))
+    (if (array-list-empty? mpool)
+        (make-identity-matrix4)
+        (array-list-pop! mpool))))
+
+(define (render-state-matrix-current state)
+  (let ((mstack (render-state-matrix-stack state)))
+    (array-list-ref mstack (- (array-list-size mstack) 1))))
 
-(define (render-state-world-matrix-mult! state matrix)
-  (let ((world (render-state-world-matrix state)))
-    (matrix4-mult! world world matrix)))
+(define (render-state-reset! state)
+  (matrix4-identity! (render-state-view-matrix state))
+  (let ((mstack (render-state-matrix-stack state))
+        (mpool (render-state-matrix-pool state)))
+    (let loop ()
+      (unless (array-list-empty? mstack)
+        (array-list-push! mpool (array-list-pop! mstack))
+        (loop)))
+    (let ((m (render-state-matrix-borrow state)))
+      (matrix4-identity! m)
+      (array-list-push! mstack m))))
 
 (define (render-state-view-matrix-mult! state matrix)
   (let ((view (render-state-view-matrix state)))
     (matrix4-mult! view view matrix)))
 
+(define (render-state-matrix-push-and-mult! state matrix)
+  (let ((new (render-state-matrix-borrow state)))
+    (matrix4-mult! new matrix (render-state-matrix-current state))
+    (array-list-push! (render-state-matrix-stack state) new)))
+
+(define (render-state-matrix-pop! state)
+  (array-list-push! (render-state-matrix-pool state)
+                    (array-list-pop! (render-state-matrix-stack state))))
+
 
 ;;;
 ;;; Primitive
@@ -100,13 +127,13 @@
 (define (draw-primitive/phong primitive state)
   (shader-apply/phong (primitive-vertex-array primitive)
                       (primitive-material primitive)
-                      (render-state-world-matrix state)
+                      (render-state-matrix-current state)
                       (render-state-view-matrix state)))
 
 (define (draw-primitive/pbr primitive state)
   (shader-apply/pbr (primitive-vertex-array primitive)
                     (primitive-material primitive)
-                    (render-state-world-matrix state)
+                    (render-state-matrix-current state)
                     (render-state-view-matrix state)))
 
 
@@ -148,13 +175,14 @@
   (%make-scene-node name mesh matrix children))
 
 (define (draw-scene-node node state)
-  ;; TODO: Apply push/pop model matrix stuff.
+  (render-state-matrix-push-and-mult! state (scene-node-matrix node))
   (for-each (lambda (child)
               (draw-scene-node child state))
             (scene-node-children node))
   (let ((mesh (scene-node-mesh node)))
     (when mesh
-      (draw-mesh mesh state))))
+      (draw-mesh mesh state)))
+  (render-state-matrix-pop! state))
 
 
 ;;;
@@ -181,7 +209,7 @@
     (let ((state (model-render-state model)))
       (render-state-reset! state)
       (render-state-view-matrix-mult! state view-matrix)
-      (render-state-world-matrix-mult! state model-matrix)
+      (render-state-matrix-push-and-mult! state model-matrix)
       ;; TODO: Support drawing non-default scenes.
       (draw-scene-node (model-default-scene model) state))))
 
@@ -977,14 +1005,27 @@
           ;; TODO: Parse skin.
           (skin #f)
           (matrix (or (matrix-ref/optional obj "matrix")
-                      (make-identity-matrix4)))
+                      (let ((rotation (or (array-ref/optional obj "rotation")
+                                          #(0.0 0.0 0.0 1.0)))
+                            (scale (or (array-ref/optional obj "scale")
+                                       #(1.0 1.0 1.0)))
+                            (translation (or (array-ref/optional obj "translation")
+                                             #(0.0 0.0 0.0))))
+                        (matrix4* (match scale
+                                    (#(x y z)
+                                     (matrix4-scale (vec3 x y z))))
+                                  (match rotation
+                                    (#(x y z w)
+                                     ;; Rotation needs to be negated
+                                     ;; for some reason.
+                                     (matrix4-rotate
+                                      (quaternion (- x) (- y) (- z) w))))
+                                  (match translation
+                                    (#(x y z)
+                                     (matrix4-translate (vec3 x y z))))))))
           (mesh (match (number-ref/optional obj "mesh")
                   (#f #f)
                   (n (vector-ref meshes n))))
-          ;; TODO: Parse rotation, scale, translation
-          (rotation #f)
-          (scale #f)
-          (translation #f)
           ;; TODO: Parse weights.
           (weights #f)
           (children (map parse-child