1 files changed, 143 insertions, 15 deletions
diff --git a/sly/render/mesh.scm b/sly/render/mesh.scm
index 992ef85..98510d3 100644
--- a/sly/render/mesh.scm
+++ b/sly/render/mesh.scm
@@ -17,29 +17,157 @@
 
 ;;; Commentary:
 ;;
-;; A mesh is a 2D/3D model comprised of a shader and vertex buffers.
+;; Meshes encapsulate the geometry for a single OpenGL draw call.
 ;;
 ;;; Code:
 
 (define-module (sly render mesh)
-  #:use-module (oop goops)
+  #:use-module (system foreign)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-9)
-  #:use-module (system foreign)
+  #:use-module (srfi srfi-43)
+  #:use-module (rnrs bytevectors)
   #:use-module (gl)
   #:use-module (gl low-level)
   #:use-module (sly wrappers gl)
+  #:use-module (sly math vector)
   #:use-module (sly render color)
   #:use-module (sly render shader)
-  #:use-module (sly render texture)
-  #:use-module (sly math vector)
-  #:use-module (sly signal)
-  #:use-module (sly math transform)
-  #:use-module (sly render utils)
-  #:use-module (sly render vertex-array)
-  #:use-module (sly render model)
-  #:export (make-mesh))
-
-(define* (make-mesh #:optional #:key shader texture indices positions textures)
-  (make-model #:shader shader #:texture texture
-              #:mesh (make-vertex-array indices positions textures)))
+  #:export (make-mesh
+            mesh?
+            mesh-id mesh-length
+            apply-mesh with-mesh))
+
+;;;
+;;; Vertex Buffer
+;;;
+
+(define-record-type <vertex-buffer>
+  (%make-vertex-buffer id type attr-size length)
+  vertex-buffer?
+  (id vertex-buffer-id)
+  (type vertex-buffer-type)
+  (attr-size vertex-buffer-attr-size)
+  (length vertex-buffer-length))
+
+(define (generate-vertex-buffer)
+  (let ((bv (u32vector 1)))
+    (glGenBuffers 1 (bytevector->pointer bv))
+    (u32vector-ref bv 0)))
+
+(define (bind-vertex-buffer vbo)
+  (glBindBuffer (vertex-buffer-type vbo)
+                (vertex-buffer-id vbo)))
+
+(define-syntax-rule (with-vertex-buffer vbo body ...)
+  (let ((type (vertex-buffer-type vbo)))
+    (glBindBuffer type (vertex-buffer-id vbo))
+    body ...
+    (glBindBuffer type 0)))
+
+(define (vertices-bytevector vertices index?)
+  (let* ((elem (vector-ref vertices 0))
+         (bv (if index?
+                 (make-u32vector (vector-length vertices))
+                 (make-f32vector (* (vector-length vertices)
+                                    (attribute-size elem)))))
+         (setter (if index? u32vector-set! f32vector-set!)))
+    (vector-for-each
+     (match-lambda*
+      ((i (? number? k))
+       (setter bv i k))
+      ((i ($ <vector2> x y))
+       (let ((offset (* i 2)))
+         (setter bv offset x)
+         (setter bv (1+ offset) y)))
+      ((i ($ <vector3> x y z))
+       (let ((offset (* i 3)))
+         (setter bv offset x)
+         (setter bv (1+ offset) y)
+         (setter bv (+ offset 2) z)))
+      ((i ($ <vector4> x y z w))
+       (let ((offset (* i 4)))
+         (setter bv offset x)
+         (setter bv (1+ offset) y)
+         (setter bv (+ offset 2) z)
+         (setter bv (+ offset 3) w)))
+      ((i (color? c))
+       (let ((offset (* i 4)))
+         (setter bv offset (color-r c))
+         (setter bv (1+ offset) (color-g c))
+         (setter bv (+ offset 2) (color-b c))
+         (setter bv (+ offset 3) (color-a c)))))
+     vertices)
+    bv))
+
+(define attribute-size
+  (match-lambda
+   ((? number? _) 1)
+   ((? vector2? _) 2)
+   ((? vector3? _) 3)
+   ((or (? vector4? _)
+        (? color? _))
+    4)
+   (attr
+    (error "Unsupported vertex buffer attribute: " attr))))
+
+(define (gl-buffer-type index?)
+  (if index?
+      (arb-vertex-buffer-object element-array-buffer-arb)
+      (arb-vertex-buffer-object array-buffer-arb)))
+
+(define* (make-vertex-buffer vertices #:optional (index? #f))
+  (let ((bv (vertices-bytevector vertices index?))
+        (vbo (%make-vertex-buffer (generate-vertex-buffer)
+                                  (gl-buffer-type index?)
+                                  (attribute-size (vector-ref vertices 0))
+                                  (vector-length vertices))))
+    (with-vertex-buffer vbo
+      (glBufferData (vertex-buffer-type vbo)
+                    (bytevector-length bv)
+                    (bytevector->pointer bv)
+                    (arb-vertex-buffer-object static-draw-arb)))
+    vbo))
+
+;;;
+;;; Mesh
+;;;
+
+(define-record-type <mesh>
+  (%make-mesh id length)
+  mesh?
+  (id mesh-id)
+  (length mesh-length))
+
+(define (generate-vertex-array)
+  (let ((bv (u32vector 1)))
+    (glGenVertexArrays 1 (bytevector->pointer bv))
+    (u32vector-ref bv 0)))
+
+(define (apply-mesh vao)
+  (glBindVertexArray (mesh-id vao)))
+
+;; emacs: (put 'with-mesh 'scheme-indent-function 1)
+(define-syntax-rule (with-mesh vao body ...)
+  (begin
+    (apply-mesh vao)
+    body ...
+    (glBindVertexArray 0)))
+
+(define (vertex-attrib-pointer location vbo)
+  (glEnableVertexAttribArray location)
+  (with-vertex-buffer vbo
+    (glVertexAttribPointer location (vertex-buffer-attr-size vbo)
+                           (data-type float) #f 0 %null-pointer)))
+
+(define (make-mesh indices positions textures)
+  (let ((mesh (%make-mesh (generate-vertex-array)
+                          (vector-length indices)))
+        (positions (make-vertex-buffer positions))
+        (textures (make-vertex-buffer textures)))
+    (with-mesh mesh
+      (vertex-attrib-pointer vertex-position-location positions)
+      (if textures
+          (vertex-attrib-pointer vertex-texture-location textures))
+      (bind-vertex-buffer (make-vertex-buffer indices #t)))
+    mesh))