From 026e42f212da6bcc6fc533e8419029df2afea936 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Wed, 23 Oct 2019 08:07:21 -0400
Subject: render: shader: Allow client-side only fields in shader structs.

---
 chickadee/render/shader.scm | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/chickadee/render/shader.scm b/chickadee/render/shader.scm
index 5442097..0b0e631 100644
--- a/chickadee/render/shader.scm
+++ b/chickadee/render/shader.scm
@@ -45,10 +45,11 @@
             float-vec4
             mat4
             sampler-2d
+            local-field
+            define-shader-type
             uniform-namespace?
             uniform-namespace-ref
             uniform-namespace-for-each
-            define-shader-type
             make-shader
             shader?
             null-shader
@@ -238,6 +239,8 @@
                  (format port "#<shader-struct ~a>"
                          (shader-struct-fields vt)))))
 
+(define local-field (gensym "local-shader-field-"))
+
 (define (shader-struct? struct)
   (eq? (struct-vtable (struct-vtable struct)) <shader-struct>))
 
@@ -258,6 +261,8 @@
                    (shader-data-type-validate type value))
          (error "invalid type for shader struct field" field value)))
      (cond
+      ((eq? type local-field)
+       #t)
       ((= size 1)
        (validate value))
       ((and (vector? value)
@@ -306,7 +311,11 @@
         (() #f)
         (((name index type size) . rest)
          (format port " ~a[~d ~a]: ~a"
-                 name size (shader-data-type-name type) (struct-ref obj index))
+                 name size
+                 (if (eq? type local-field)
+                     'local
+                     (shader-data-type-name type))
+                 (struct-ref obj index))
          (loop rest))))
     (display ">" port)))
 
-- 
cgit v1.2.3