render: camera: Add null-viewport.

* sly/render/camera.scm (null-viewport): New variable.

1 files changed, 3 insertions, 0 deletions

diff --git a/sly/render/camera.scm b/sly/render/camera.scm
index a9b8e41..48a66b2 100644
--- a/sly/render/camera.scm
+++ b/sly/render/camera.scm
@@ -35,6 +35,7 @@
   #:export (make-viewport viewport?
             viewport-area viewport-clear-color viewport-clear-flags
             %standard-clear-flags apply-viewport
+            null-viewport
             make-camera camera?
             camera-location camera-projection camera-viewport
             orthographic-camera))
@@ -61,6 +62,8 @@ values for CLEAR-FLAGS are 'color-buffer', 'depth-buffer',
 'accum-buffer', and 'stencil-buffer'."
   (%make-viewport area clear-color clear-flags))
 
+(define null-viewport (make-viewport (make-rect 0 0 0 0)))
+
 (define clear-buffer-mask
   (memoize
    (lambda (flags)