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|
;;; Chickadee Game Toolkit
;;; Copyright © 2019, 2021 David Thompson <davet@gnu.org>
;;;
;;; Chickadee is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published
;;; by the Free Software Foundation, either version 3 of the License,
;;; or (at your option) any later version.
;;;
;;; Chickadee is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; 3D Model loading and rendering.
;;
;;; Code:
(define-module (chickadee graphics model)
#:use-module (chickadee array-list)
#: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)
#:use-module (chickadee graphics depth)
#:use-module (chickadee graphics engine)
#:use-module (chickadee graphics pbr)
#:use-module (chickadee graphics phong)
#:use-module (chickadee graphics shader)
#:use-module (chickadee graphics texture)
#:use-module (chickadee utils)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (ice-9 rdelim)
#:use-module (rnrs bytevectors)
#:use-module (rnrs io ports)
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module ((srfi srfi-43) #:select (vector-every))
#:use-module (web uri)
#:export (scene-node?
scene-node-name
scene-node-mesh
scene-node-matrix
scene-node-children
model?
model-scenes
model-default-scene
draw-model
load-obj
load-gltf))
;;;
;;; Rendering State
;;;
(define-record-type <render-state>
(%make-render-state renderer view-matrix
matrix-stack matrix-pool)
render-state?
(renderer render-state-renderer)
(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-array-list)
(array-list (make-identity-matrix4))))
(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-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
;;;
;; A piece of a mesh. Represents a single draw call.
(define-record-type <primitive>
(make-primitive name vertex-array material)
primitive?
(name primitive-name)
(vertex-array primitive-vertex-array)
(material primitive-material))
(define (draw-primitive/phong primitive state)
(shader-apply/phong (primitive-vertex-array primitive)
(primitive-material primitive)
(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-matrix-current state)
(render-state-view-matrix state)))
;;;
;;; Mesh
;;;
;; A complete 3D model composed of many primitives.
(define-record-type <mesh>
(make-mesh name primitives)
mesh?
(name mesh-name)
(primitives mesh-primitives))
(define (draw-mesh mesh state)
(let ((render (render-state-renderer state)))
(for-each (lambda (primitive) (render primitive state))
(mesh-primitives mesh))))
;;;
;;; Scene Node
;;;
;; A tree of meshes with their own transformation matrices.
(define-record-type <scene-node>
(%make-scene-node name mesh matrix children)
scene-node?
(name scene-node-name)
(mesh scene-node-mesh)
(matrix scene-node-matrix)
(children scene-node-children))
(define* (make-scene-node #:key
(name "anonymous")
mesh
(matrix (make-identity-matrix4))
(children '()))
(%make-scene-node name mesh matrix children))
(define (draw-scene-node node state)
(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)))
(render-state-matrix-pop! state))
;;;
;;; Model
;;;
;; A collection of scenes and the associated information about *how*
;; to actually render the darn thing.
(define-record-type <model>
(%make-model name scenes default-scene render-state)
model?
(name model-name)
(scenes model-scenes)
(default-scene model-default-scene)
(render-state model-render-state))
(define* (make-model #:key name scenes (default-scene (car scenes)) render-state)
(%make-model name scenes default-scene render-state))
(define %depth-test (make-depth-test))
(define (draw-model model model-matrix view-matrix)
(with-graphics-state ((g:depth-test %depth-test))
(let ((state (model-render-state model)))
(render-state-reset! state)
(render-state-view-matrix-mult! state view-matrix)
(render-state-matrix-push-and-mult! state model-matrix)
;; TODO: Support drawing non-default scenes.
(draw-scene-node (model-default-scene model) state))))
;;;
;;; OBJ Format
;;;
;; Reference documentation:
;; * http://paulbourke.net/dataformats/obj
;; * http://paulbourke.net/dataformats/mtl
(define (load-obj file-name)
(define (scope-file other-file)
(string-append (dirname file-name) "/" other-file))
(call-with-input-file file-name
(lambda (port)
(let ((vertices (make-array-list))
(texcoords (make-array-list))
(normals (make-array-list))
(faces (make-array-list))
(face-map (make-hash-table))
(face-indices-map (make-hash-table))
(material-map (make-hash-table)))
(define (parse-map-args args)
(define (map-option? str)
(string-prefix? "-" str))
(let loop ((args args)
(opts '()))
(match args
(() opts)
(((? map-option? opt) arg . rest)
(loop rest
(cons (cons (string->symbol
(substring opt 1))
arg)
opts)))
((file-name . rest)
(loop rest (cons (cons 'file-name file-name) opts))))))
(define (load-mtl mtl-file-name)
(define (scope-file other-file)
(string-append (dirname mtl-file-name) "/" other-file))
(call-with-input-file mtl-file-name
(lambda (port)
(let loop ((opts '()))
(define (maybe-add-material)
(let ((name (assq-ref opts 'name)))
(when name
(hash-set! material-map
name
(make-phong-material
#:name name
#:ambient (assq-ref opts 'ambient)
#:ambient-map (assq-ref opts 'ambient-map)
#:use-ambient-map
(assq-ref opts 'use-ambient-map?)
#:diffuse (assq-ref opts 'diffuse)
#:diffuse-map (assq-ref opts 'diffuse-map)
#:use-diffuse-map
(assq-ref opts 'use-diffuse-map?)
#:specular (assq-ref opts 'specular)
#:specular-map (assq-ref opts 'specular-map)
#:use-specular-map
(assq-ref opts 'use-specular-map?)
#:shininess (assq-ref opts 'shininess)
#:bump-map (assq-ref opts 'bump-map)
#:use-bump-map
(assq-ref opts 'use-bump-map?))))))
(match (read-line port)
((? eof-object?)
(maybe-add-material))
(line
(match (delete "" (string-split line char-set:whitespace))
((or () ("#" . _)) ; ignore comments and blank lines
(loop opts))
(("d" d) ; ignore dissolve for now
(loop opts))
(("illum" n) ; ignore illumation model for now
(loop opts))
(("Ka" r g b) ; ambient factor
(let ((new-ambient (vec3 (string->number r)
(string->number g)
(string->number b))))
(loop (cons (cons 'ambient new-ambient) opts))))
(("Ka" r) ; ambient factor
(let ((new-ambient (vec3 (string->number r)
(string->number r)
(string->number r))))
(loop (cons (cons 'ambient new-ambient) opts))))
(("Kd" r g b) ; diffuse factor
(let ((new-diffuse (vec3 (string->number r)
(string->number g)
(string->number b))))
(loop (cons (cons 'diffuse new-diffuse) opts))))
(("Kd" r) ; diffuse factor
(let ((new-diffuse (vec3 (string->number r)
(string->number r)
(string->number r))))
(loop (cons (cons 'diffuse new-diffuse) opts))))
(("Ks" r g b) ; specular factor
(let ((new-specular (vec3 (string->number r)
(string->number g)
(string->number b))))
(loop (cons (cons 'specular new-specular) opts))))
(("Ks" r) ; specular factor
(let ((new-specular (vec3 (string->number r)
(string->number r)
(string->number r))))
(loop (cons (cons 'specular new-specular) opts))))
(("Ni" i) ; ignore optical density for now
(loop opts))
(("Ns" s) ; specular exponent (shininess)
;; Force specular exponent to be a float.
(let ((new-shininess (* (string->number s) 1.0)))
(loop (cons (cons 'shininess new-shininess) opts))))
(("map_Ka" . args) ; ambient map
(let* ((ambient-opts (parse-map-args args))
(file (scope-file (assq-ref ambient-opts
'file-name)))
(texture (load-image file
#:min-filter 'linear
#:mag-filter 'linear)))
(loop (cons* (cons 'ambient-map texture)
(cons 'use-ambient-map? #t)
opts))))
(("map_Kd" . args) ; diffuse map
(let* ((diffuse-opts (parse-map-args args))
(file (scope-file (assq-ref diffuse-opts
'file-name)))
(texture (load-image file
#:min-filter 'linear
#:mag-filter 'linear)))
(loop (cons* (cons 'diffuse-map texture)
(cons 'use-diffuse-map? #t)
opts))))
(("map_Ks" . args) ; specular map
(let* ((specular-opts (parse-map-args args))
(file (scope-file (assq-ref specular-opts
'file-name)))
(texture (load-image file
#:min-filter 'linear
#:mag-filter 'linear)))
(loop (cons* (cons 'specular-map texture)
(cons 'use-specular-map? #t)
opts))))
(((or "map_Bump" "map_bump" "bump") . args) ; normal map
(let* ((bump-opts (parse-map-args args))
(file (scope-file (assq-ref bump-opts
'file-name)))
(texture (load-image file
#:min-filter 'linear
#:mag-filter 'linear)))
(loop (cons* (cons 'bump-map texture)
(cons 'use-bump-map? #t)
opts))))
(("newmtl" new-name)
;; Begin new material
(maybe-add-material)
(loop `((name . ,new-name)
(ambient . ,(vec3 0.0 0.0 0.0))
(ambient-map . ,null-texture)
(use-ambient-map? . #f)
(diffuse . ,(vec3 0.0 0.0 0.0))
(diffuse-map . ,null-texture)
(use-diffuse-map? . #f)
(specular . ,(vec3 0.0 0.0 0.0))
(specular-map . ,null-texture)
(use-specular-map? . #f)
(shininess . 1.0)
(bump-map . ,null-texture)
(use-bump-map? . #f))))
(data
(format (current-error-port)
"warning: ~a:~d: unsupported MTL data: ~s~%"
mtl-file-name
(port-line port)
data)
(loop opts)))))))))
(define (parse-error message args)
(apply error (format #f "OBJ parser error @ ~a:~d: ~a"
file-name
(port-line port)
message)
args))
(define (parse-vertex args)
(array-list-push! vertices
(match args
((x y z)
(vec3 (string->number x)
(string->number y)
(string->number z)))
;; TODO: handle w properly
((x y z w)
(vec3 (string->number x)
(string->number y)
(string->number z)))
(_
(parse-error "wrong number of vertex arguments" args)))))
(define (parse-texcoord args)
;; TODO: Handle w properly.
(array-list-push! texcoords
(match args
((u)
(vec2 (string->number u) 0.0))
((u v)
;; OBJ texture coordinates use the
;; top-left of the image as the origin,
;; but OpenGL uses the bottom-left, so
;; all V values must be inverted.
(vec2 (string->number u)
(- 1.0 (string->number v))))
((u v w)
(vec2 (string->number u)
(- 1.0 (string->number v))))
(_
(parse-error "wrong number of texcoord arguments" args)))))
(define (parse-normal args)
(array-list-push! normals
(match args
((i j k)
(vec3 (string->number i)
(string->number j)
(string->number k)))
(_
(parse-error "wrong number of normal arguments" args)))))
(define (parse-face-index arg)
(- (string->number arg) 1))
(define (parse-face-element arg)
(match (string-split arg #\/)
((v)
(list (parse-face-index v) #f #f))
((v t)
(list (parse-face-index v)
(parse-face-index t)
#f))
((v "" n)
(list (parse-face-index v)
#f
(parse-face-index n)))
((v t n)
(list (parse-face-index v)
(parse-face-index t)
(parse-face-index n)))
(_
(parse-error "invalid face syntax" (list arg)))))
(define (indices-for-material material)
(or (hash-ref face-indices-map material)
(let ((new-indices (make-array-list)))
(hash-set! face-indices-map material new-indices)
new-indices)))
(define (deduplicate-face-element e)
;; Faces are often redundant, so we deduplicate in order to
;; make the VBOs we build later as small as possible.
(or (hash-ref face-map e)
(let ((i (array-list-size faces)))
(array-list-push! faces (parse-face-element e))
(hash-set! face-map e i)
i)))
(define (push-face material e)
(array-list-push! (indices-for-material material)
(deduplicate-face-element e)))
(define (parse-face args material)
(match args
;; A single triangle. Ah, life is so simple...
((a b c)
(push-face material a)
(push-face material b)
(push-face material c))
;; A quadrilateral. Needs to be split into 2 triangles.
;;
;; d-------c
;; | /|
;; | / |
;; | / |
;; |/ |
;; a-------b
((a b c d)
;; triangle 1: a b c
(push-face material a)
(push-face material b)
(push-face material c)
;; triangle 2: a c d
(push-face material a)
(push-face material c)
(push-face material d))
;; 3 or more triangles. Interpret as a strip of triangles
;; moving from right to left (because counter-clockwise
;; winding) like this:
;;
;; h-------f-------d-------c
;; | /| /| /|
;; | / | / | / |
;; | / | / | / |
;; |/ |/ |/ |
;; g-------e-------a-------b
;;
;; ... and so on for however many face elements there are.
;; Every other triangle is flipped over, hence the 'flip?'
;; flag in the loop below.
((a b . rest)
(let loop ((a a)
(b b)
(args rest)
(flip? #f))
(match args
(() #t)
((c . rest)
(push-face material a)
(push-face material b)
(push-face material c)
(if flip?
(loop c a rest #f)
(loop a c rest #t))))))
(_
(parse-error "invalid face" args))))
;; Build a vertex array for all the faces of a single
;; material.
;;
;; XXX: We assume there is normal and texture data. Models
;; that don't have one or both will still use up as much
;; memory as if they did. Maybe that's just fine? Dunno.
(define (make-primitive-for-material material)
(let* ((face-indices (indices-for-material material))
(vertex-count (array-list-size faces))
(index-count (array-list-size face-indices))
(stride 8)
(mesh-data (make-f32vector (* vertex-count stride)))
(mesh-indices (make-u32vector index-count))
(null-texcoord (vec2 0.0 0.0))
(null-normal (vec3 0.0 0.0 0.0)))
;; The mesh vertex data is packed like so:
;; - 3 floats for vertex
;; - 2 floats for texture coordinate
;; - 3 floats for normal
;; - repeat for each face
(for-range ((i vertex-count))
(let ((offset (* i stride)))
(match (array-list-ref faces i)
((vert-index tex-index norm-index)
;; Vertex
(let ((v (array-list-ref vertices vert-index)))
(f32vector-set! mesh-data offset (vec3-x v))
(f32vector-set! mesh-data (+ offset 1) (vec3-y v))
(f32vector-set! mesh-data (+ offset 2) (vec3-z v)))
;; Texture coordinate
(let ((t (if tex-index
(array-list-ref texcoords tex-index)
null-texcoord)))
(f32vector-set! mesh-data (+ offset 3) (vec2-x t))
(f32vector-set! mesh-data (+ offset 4) (vec2-y t)))
;; Normal
(let ((n (if norm-index
(array-list-ref normals norm-index)
null-normal)))
(f32vector-set! mesh-data (+ offset 5) (vec3-x n))
(f32vector-set! mesh-data (+ offset 6) (vec3-y n))
(f32vector-set! mesh-data (+ offset 7) (vec3-z n)))))))
;; Pack indices.
(for-range ((i index-count))
(u32vector-set! mesh-indices i (array-list-ref face-indices i)))
;; Construct vertex array.
;; TODO: Add names to buffers and views.
(let* ((index-buffer (make-buffer mesh-indices #:target 'index))
(index-view (make-buffer-view #:type 'scalar
#:component-type 'unsigned-int
#:buffer index-buffer))
(data-buffer (make-buffer mesh-data #:stride (* stride 4)))
(vertex-view (make-buffer-view #:type 'vec3
#:component-type 'float
#:buffer data-buffer))
(texcoord-view (make-buffer-view #:type 'vec2
#:component-type 'float
#:buffer data-buffer
#:offset 12))
(normal-view (make-buffer-view #:type 'vec3
#:component-type 'float
#:buffer data-buffer
#:offset 20)))
(make-primitive material
(make-vertex-array
#:indices index-view
#:attributes `((0 . ,vertex-view)
(1 . ,texcoord-view)
(2 . ,normal-view)))
(or (hash-ref material-map material)
(hash-ref material-map "default"))))))
;; Register default material
(hash-set! material-map "default" default-phong-material)
;; Parse file.
(let loop ((material "default"))
(match (read-line port)
((? eof-object?)
#f)
(line
(match (delete "" (string-split line char-set:whitespace))
((or () ("#" . _)) ; ignore comments and blank lines
(loop material))
(("f" . args)
(parse-face args material)
(loop material))
(("g" . _) ; ignore group name for now
(loop material))
(("mtllib" mtl-file-name)
(load-mtl (scope-file mtl-file-name))
(loop material))
(("o" . _) ;ignore object name for now
(loop material))
(("s" . _) ; ignore smoothing group for now
(loop material))
(("usemtl" new-material)
(loop new-material))
(("v" . args)
(parse-vertex args)
(loop material))
(("vn" . args)
(parse-normal args)
(loop material))
(("vt" . args)
(parse-texcoord args)
(loop material))
(data
(format (current-error-port)
"warning: ~a:~d: unsupported OBJ data: ~s~%"
file-name
(port-line port)
data)
(loop material))))))
;; Construct a mesh by composing primitives. One primitive
;; per material.
(let* ((model-name (basename file-name))
(mesh (make-mesh model-name
(hash-fold (lambda (material indices memo)
;; It's possible that a material has
;; no data associated with it, so we
;; drop those.
(if (array-list-empty? indices)
memo
(cons (make-primitive-for-material material)
memo)))
'()
face-indices-map)))
(scene (make-scene-node #:name model-name
#:mesh mesh)))
(make-model #:name model-name
#:scenes (list scene)
#:render-state
(make-render-state draw-primitive/phong)))))))
;;;
;;; glTF 2.0
;;;
(define (load-gltf file-name)
(define (object-ref obj key)
(let ((value (assoc-ref obj key)))
(unless (pair? value)
(error "expected object for key" key value))
value))
(define (object-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (or (not value) (pair? value) (null? value))
(error "expected object for optional key" key value))
value))
(define (array-ref obj key)
(let ((value (assoc-ref obj key)))
(unless (vector? value)
(error "expected array for key" key value))
value))
(define (array-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (or (not value) (vector? value))
(error "expected array for optional key" key value))
value))
(define (string-ref obj key)
(let ((value (assoc-ref obj key)))
(unless (string? value)
(error "expected string for key" key value))
value))
(define (string-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (or (not value) (string? value))
(error "expected string for optional key" key value))
value))
(define (number-ref obj key)
(let ((value (assoc-ref obj key)))
(unless (number? value)
(error "expected number for key" key value))
value))
(define (number-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (or (not value) (number? value))
(error "expected number for key" key value))
value))
(define (boolean-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (boolean? value)
(error "expected boolean for key" key value))
value))
(define (number-array-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(unless (or (not value)
(and (vector? value) (vector-every number? value)))
(error "expected numeric array for key" key value))
value))
(define (matrix-ref/optional obj key)
(let ((value (assoc-ref obj key)))
(cond
((not value) #f)
((and (vector? value)
(= (vector-length value) 16)
(vector-every number? value))
;; glTF matrices are in column-major order.
(make-matrix4 (vector-ref value 0)
(vector-ref value 4)
(vector-ref value 8)
(vector-ref value 12)
(vector-ref value 1)
(vector-ref value 5)
(vector-ref value 9)
(vector-ref value 13)
(vector-ref value 2)
(vector-ref value 6)
(vector-ref value 10)
(vector-ref value 14)
(vector-ref value 3)
(vector-ref value 7)
(vector-ref value 11)
(vector-ref value 15)))
(else
(error "expected 4x4 matrix for key" key value)))))
(define (assert-color v)
(if (and (= (vector-length v) 4)
(vector-every (lambda (x) (and (>= x 0.0) (<= x 1.0))) v))
(make-color (vector-ref v 0)
(vector-ref v 1)
(vector-ref v 2)
(vector-ref v 3))
(error "not a color vector" v)))
(define scope-file
(let ((gltf-root (dirname
(if (absolute-file-name? file-name)
file-name
(string-append (getcwd) "/" file-name)))))
(lambda (other-file)
(if (absolute-file-name? other-file)
other-file
(string-append gltf-root "/" other-file)))))
(define base64-prefix "data:application/octet-stream;base64,")
(define (parse-buffer obj)
;; TODO: support glb-stored buffers:
;; https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#glb-stored-buffer
(let* ((uri (string-ref/optional obj "uri"))
(length (number-ref obj "byteLength"))
(name (or (string-ref/optional obj "name") "anonymous"))
(extensions (object-ref/optional obj "extensions"))
(extras (assoc-ref obj "extras"))
(data (cond
((string-prefix? base64-prefix uri)
(base64-decode (substring uri (string-length base64-prefix))))
(uri
(call-with-input-file (scope-file (uri-decode uri))
(lambda (port)
(get-bytevector-n port length))))
(else
(make-bytevector length)))))
data))
(define (parse-buffer-view obj buffers)
(let ((name (string-ref/optional obj "name"))
(data (vector-ref buffers (number-ref obj "buffer")))
(offset (or (number-ref/optional obj "byteOffset") 0))
(length (number-ref obj "byteLength"))
(stride (number-ref/optional obj "byteStride"))
(target (match (or (number-ref/optional obj "target") 34962)
(34962 'vertex)
(34963 'index)))
(extensions (object-ref/optional obj "extensions"))
(extras (assoc-ref obj "extras")))
(make-buffer data
#:name name
#:offset offset
#:length length
#:stride stride
#:target target)))
(define (parse-accessor obj buffer-views)
(define (type-length type)
(match type
('scalar 1)
('vec2 2)
('vec3 3)
('vec4 4)
('mat2 4)
('mat3 9)
('mat4 16)))
(let ((name (or (string-ref/optional obj "name") "anonymous"))
(view (match (number-ref/optional obj "bufferView")
(#f #f)
(n (vector-ref buffer-views n))))
(offset (or (number-ref/optional obj "byteOffset") 0))
(component-type (match (number-ref obj "componentType")
(5120 'byte)
(5121 'unsigned-byte)
(5122 'short)
(5123 'unsigned-short)
(5125 'unsigned-int)
(5126 'float)))
(normalized? (boolean-ref/optional obj "normalized"))
(length (number-ref obj "count"))
(type (match (string-ref obj "type")
("SCALAR" 'scalar)
("VEC2" 'vec2)
("VEC3" 'vec3)
("VEC4" 'vec4)
("MAT2" 'mat2)
("MAT3" 'mat3)
("MAT4" 'mat4)))
(max (number-array-ref/optional obj "max"))
(min (number-array-ref/optional obj "min"))
(sparse (object-ref/optional obj "sparse"))
(extensions (object-ref/optional obj "extensions"))
(extras (assoc-ref obj "extras")))
(unless (>= length 1)
(error "count must be greater than 0" length))
(when (and (vector? max)
(not (= (vector-length max) (type-length type))))
(error "not enough elements for max" max type))
(when (and (vector? min)
(not (= (vector-length min) (type-length type))))
(error "not enough elements for min" min type))
(make-buffer-view #:name name
#:buffer view
#:offset offset
#:component-type component-type
#:normalized? normalized?
#:length length
#:type type
#:max max
#:min min
#:sparse sparse)))
(define (texture-filter n)
(match n
(9728 'nearest)
((or #f 9729) 'linear)
;; TODO: Support mip-mapping
;; (9984 'nearest-mipmap-nearest)
;; (9985 'linear-mipmap-nearest)
;; (9986 'nearest-mipmap-linear)
;; (9987 'linear-mipmap-linear)
(_ 'linear)))
(define (texture-wrap n)
(match n
(10496 'clamp)
(10497 'repeat)
(33069 'clamp-to-border)
(33071 'clamp-to-edge)
;; TODO: Support mirrored repeat.
(_ 'repeat)))
(define (parse-texture obj images samplers)
(let ((image (vector-ref images (number-ref obj "source")))
(sampler
(vector-ref samplers (or (number-ref/optional obj "sampler") 0))))
(load-image (scope-file (uri-decode (string-ref image "uri")))
#:min-filter (texture-filter
(number-ref/optional sampler "minFilter"))
#:mag-filter (texture-filter
(number-ref/optional sampler "magFilter"))
#:wrap-s (texture-wrap (number-ref/optional sampler "wrapS"))
#:wrap-t (texture-wrap (number-ref/optional sampler "wrapT"))
#:flip? #f)))
(define (parse-material obj textures)
(let* ((name (or (string-ref/optional obj "name") "anonymous"))
(pbrmr (or (object-ref/optional obj "pbrMetallicRoughness") '()))
(base-color-factor
(let ((v (or (number-array-ref/optional pbrmr "baseColorFactor")
#(1.0 1.0 1.0 1.0))))
(vec3 (vector-ref v 0) (vector-ref v 1) (vector-ref v 2))))
(metallic-factor
(or (number-ref/optional pbrmr "metallicFactor")
1.0))
(roughness-factor
(or (number-ref/optional pbrmr "roughnessFactor")
1.0))
(normal-factor
(let ((v (or (array-ref/optional obj "normalFactor")
#(1.0 1.0 1.0))))
(vec3 (vector-ref v 0) (vector-ref v 1) (vector-ref v 2))))
(occlusion-factor
(let ((v (or (array-ref/optional obj "occlusionFactor")
#(1.0 1.0 1.0))))
(vec3 (vector-ref v 0) (vector-ref v 1) (vector-ref v 2))))
(emissive-factor
(let ((v (or (array-ref/optional obj "emissiveFactor")
#(1.0 1.0 1.0))))
(vec3 (vector-ref v 0) (vector-ref v 1) (vector-ref v 2))))
;; TODO: Sort primitives such that all OPAQUE and MASK
;; objects are drawn first, then draw primitives with
;; BLEND.
(alpha-mode (match (or (string-ref/optional obj "alphaMode")
"OPAQUE")
("OPAQUE" 0)
("MASK" 1)
("BLEND" 2)))
(alpha-cutoff (or (number-ref/optional obj "alphaCutoff") 0.5))
(double-sided? (boolean-ref/optional obj "doubleSided"))
(extensions (object-ref/optional obj "extensions"))
(extras (assoc-ref obj "extras")))
(define (parse-texture obj key)
(match (object-ref/optional obj key)
(#f (values null-texture 0))
(texture
(values (vector-ref textures (number-ref texture "index"))
(or (number-ref/optional texture "texCoord") 0)))))
(define (non-null-texture? texture)
(not (eq? texture null-texture)))
(let-values (((base-color-texture base-color-texcoord)
(parse-texture pbrmr "baseColorTexture"))
((normal-texture normal-texcoord)
(parse-texture obj "normalTexture"))
((occlusion-texture occlusion-texcoord)
(parse-texture obj "occlusionTexture"))
((emissive-texture emissive-texcoord)
(parse-texture obj "emissiveTexture")))
(make-pbr-material #:name name
#:base-color-factor base-color-factor
#:base-color-texture base-color-texture
#:base-color-texture-enabled (non-null-texture? base-color-texture)
#:base-color-texcoord base-color-texcoord
#:metallic-factor metallic-factor
#:roughness-factor roughness-factor
#:normal-factor normal-factor
#:normal-texture normal-texture
#:normal-texture-enabled (non-null-texture? normal-texture)
#:normal-texcoord normal-texcoord
#:occlusion-factor occlusion-factor
#:occlusion-texture occlusion-texture
#:occlusion-texture-enabled (non-null-texture? occlusion-texture)
#:occlusion-texcoord occlusion-texcoord
#:emissive-factor emissive-factor
#:emissive-texture emissive-texture
#:emissive-texture-enabled (non-null-texture? emissive-texture)
#:emissive-texcoord emissive-texcoord
#:alpha-mode alpha-mode
#:alpha-cutoff alpha-cutoff
#:double-sided? double-sided?))))
(define (attribute-name->index name)
(let ((shader (graphics-variable-ref pbr-shader)))
(match name
("POSITION"
(attribute-location
(hash-ref (shader-attributes shader) "position")))
("NORMAL" 9)
("TANGENT" 10)
("TEXCOORD_0"
(attribute-location
(hash-ref (shader-attributes shader) "texcoord0")))
("TEXCOORD_1"
(attribute-location
(hash-ref (shader-attributes shader) "texcoord1")))
("COLOR_0"
(attribute-location
(hash-ref (shader-attributes shader) "color0")))
("JOINTS_0" 12)
("WEIGHTS_0" 13))))
(define (parse-primitive obj materials accessors)
(let ((attributes (map (match-lambda
((name . n)
(cons (attribute-name->index name)
(vector-ref accessors n))))
(object-ref obj "attributes")))
(indices (match (number-ref/optional obj "indices")
(#f #f)
(n (vector-ref accessors n))))
(material (match (number-ref/optional obj "material")
(#f default-pbr-material)
(n (vector-ref materials n))))
(mode (match (or (number-ref/optional obj "mode") 4)
(0 'points)
(1 'lines)
(2 'line-loop)
(3 'line-strip)
(4 'triangles)
(5 'triangle-strip)
(6 'triangle-fan)))
;; TODO: Support morph targets.
(targets #f))
(make-primitive "primitive"
(make-vertex-array #:indices indices
#:attributes attributes
#:mode mode)
material)))
(define (parse-mesh obj materials accessors)
(let ((name (or (string-ref/optional obj "name") "anonymous"))
(primitives
(map (lambda (obj)
(parse-primitive obj materials accessors))
(vector->list (array-ref obj "primitives"))))
(weights (number-array-ref/optional obj "weights")))
;; TODO: Support weights.
(make-mesh name primitives)))
(define (parse-node obj parse-child meshes)
;; TODO: Parse all fields of nodes.
(let ((name (or (string-ref/optional obj "name") "anonymous"))
;; TODO: Parse camera.
(camera #f)
;; TODO: Parse skin.
(skin #f)
(matrix (or (matrix-ref/optional obj "matrix")
(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 weights.
(weights #f)
(children (map parse-child
(vector->list
(or (array-ref/optional obj "children")
#())))))
(make-scene-node #:name name
#:children children
#:matrix matrix
#:mesh mesh)))
(define (parse-nodes array meshes)
(define nodes (make-vector (vector-length array) #f))
(define (parse-node* i)
(let ((node (vector-ref nodes i)))
(or node
(let ((node (parse-node (vector-ref array i)
parse-node*
meshes)))
(vector-set! nodes i node)
node))))
(for-range ((i (vector-length array)))
(parse-node* i))
nodes)
(define (parse-scene obj nodes)
(let ((name (or (string-ref/optional obj "name") "anonymous"))
(children
(map (lambda (i) (vector-ref nodes i))
(vector->list
(or (number-array-ref/optional obj "nodes")
#())))))
(make-scene-node #:name name #:children children)))
(define (vector-map proc v)
(let ((new-v (make-vector (vector-length v))))
(for-range ((i (vector-length v)))
(vector-set! new-v i (proc (vector-ref v i))))
new-v))
(call-with-input-file file-name
(lambda (port)
(let* ((tree (read-json port))
(asset (object-ref tree "asset"))
(version (string-ref asset "version"))
(copyright (string-ref/optional asset "copyright"))
(generator (string-ref/optional asset "generator"))
(minimum-version (string-ref/optional asset "minVersion"))
(extensions (object-ref/optional asset "extensions"))
;; TODO: Figure out how to parse extras in a user-defined way
(extras (assoc-ref asset "extras"))
(buffers (vector-map parse-buffer
(or (assoc-ref tree "buffers") #())))
(buffer-views (vector-map (lambda (obj)
(parse-buffer-view obj buffers))
(or (assoc-ref tree "bufferViews") #())))
(accessors (vector-map (lambda (obj)
(parse-accessor obj buffer-views))
(or (assoc-ref tree "accessors") #())))
(images (or (assoc-ref tree "images") #()))
(samplers (or (assoc-ref tree "samplers") #(())))
(textures (vector-map (lambda (obj)
(parse-texture obj images samplers))
(or (assoc-ref tree "textures") #())))
(materials (vector-map (lambda (obj)
(parse-material obj textures))
(or (assoc-ref tree "materials") #())))
(meshes (vector-map (lambda (obj)
(parse-mesh obj materials accessors))
(or (assoc-ref tree "meshes") #())))
(nodes (parse-nodes (or (assoc-ref tree "nodes") #()) meshes))
(scenes (map (lambda (obj)
(parse-scene obj nodes))
(vector->list
(or (assoc-ref tree "scenes") #()))))
(default-scene (list-ref scenes
(or (number-ref/optional tree "scene")
0))))
(unless (string=? version "2.0")
(error "unsupported glTF version" version))
(make-model #:name (basename file-name)
#:scenes (list default-scene)
#:render-state
(make-render-state draw-primitive/pbr))))))
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