Convenience to create the buffer bindings spec

Shirakumo · Aug 30, 2023 · 6518ea7 · 6518ea7
1 parent 02ab58d
commit 6518ea7
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diff --git a/package.lisp b/package.lisp
@@ -599,7 +599,8 @@
    #:size
    #:bindings
    #:index-buffer
-   #:indexed-p)
+   #:indexed-p
+   #:compute-buffer-bindings)
   ;; resources/vertex-buffer.lisp
   (:export
    #:vertex-buffer

diff --git a/resources/vertex-array.lisp b/resources/vertex-array.lisp
@@ -101,3 +101,21 @@
     #++
     (%gl:draw-arrays (vertex-form array) 0 size)
     (gl:bind-vertex-array 0)))
+
+(defun compute-buffer-bindings (buffer fields)
+  (let* ((fields (loop for field in fields
+                       collect (etypecase field
+                                 (cons field)
+                                 (integer (list field :float))
+                                 (keyword (case field
+                                            (:vec2 '(2 :float))
+                                            (:vec3 '(3 :float))
+                                            (:vec4 '(4 :float))
+                                            (T (list 1 field)))))))
+         (stride (loop for (size type) in fields
+                       sum (* size (gl-type-size type)))))
+    (loop with offset = 0
+          for (size type) in fields
+          for i from 0
+          collect `(,buffer :index ,i :size ,size :offset ,offset :type ,type :stride ,stride)
+          do (incf offset (* size (gl-type-size type))))))