From 783713719bc6fb6f891191b2cba0a1c9053a3674 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Thu, 14 Sep 2023 19:53:07 -0400
Subject: graphics: Factor out GL calls in viewport module.

---
 chickadee/graphics/gpu.scm      | 13 +++++++++++++
 chickadee/graphics/viewport.scm | 27 +++++----------------------
 2 files changed, 18 insertions(+), 22 deletions(-)

diff --git a/chickadee/graphics/gpu.scm b/chickadee/graphics/gpu.scm
index 44ffa7b..93aac87 100644
--- a/chickadee/graphics/gpu.scm
+++ b/chickadee/graphics/gpu.scm
@@ -26,6 +26,7 @@
   #:use-module (gl)
   #:use-module (ice-9 match)
   #:use-module (rnrs bytevectors)
+  #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9)
   #:use-module (system foreign)
   #:export (blend-mode?
@@ -216,6 +217,7 @@
             set-gpu-texture!
             gpu-gc
             gpu-reset!
+            gpu-clear-viewport
             gpu-draw
             gpu-draw/indexed
             gpu-draw/instanced
@@ -1193,6 +1195,17 @@
   (when divisor
     (gl-vertex-attrib-divisor index divisor)))
 
+(define (gpu-clear-viewport flags)
+  (gl-clear
+   (fold (lambda (flag result)
+           (logior (match flag
+                     ('depth-buffer 256)
+                     ('accum-buffer 512)
+                     ('stencil-buffer 1024)
+                     ('color-buffer 16384))
+                   result))
+         0 flags)))
+
 (define (gpu-draw gpu mode count offset)
   (gl-draw-arrays (symbol->begin-mode mode) offset count))
 
diff --git a/chickadee/graphics/viewport.scm b/chickadee/graphics/viewport.scm
index 4258e05..9d93c0e 100644
--- a/chickadee/graphics/viewport.scm
+++ b/chickadee/graphics/viewport.scm
@@ -22,12 +22,10 @@
 (define-module (chickadee graphics viewport)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-9)
-  #:use-module (gl)
   #:use-module (chickadee utils)
   #:use-module (chickadee graphics color)
   #:use-module (chickadee graphics engine)
   #:use-module (chickadee graphics gpu)
-  #:use-module (chickadee graphics gl)
   #:export (make-viewport
             viewport?
             viewport-rect
@@ -40,12 +38,11 @@
             %default-clear-color))
 
 (define-record-type <viewport>
-  (%make-viewport rect clear-color clear-flags clear-mask)
+  (%make-viewport rect clear-color clear-flags)
   viewport?
   (rect viewport-rect)
   (clear-color viewport-clear-color)
-  (clear-flags viewport-clear-flags)
-  (clear-mask viewport-clear-mask))
+  (clear-flags viewport-clear-flags))
 
 (define %default-clear-flags '(color-buffer depth-buffer stencil-buffer))
 ;; Just a fun color from the Dawnbringer 32-color palette instead of
@@ -57,19 +54,6 @@
       n
       (error "expecting non-negative integer:" n)))
 
-;; TODO: This is gross. Get rid of it.
-(define clear-buffer-mask
-  (memoize
-   (lambda (flags)
-     (apply logior
-            ;; Map symbols to OpenGL constants.
-            (map (match-lambda
-                   ('depth-buffer 256)
-                   ('accum-buffer 512)
-                   ('stencil-buffer 1024)
-                   ('color-buffer 16384))
-                 flags)))))
-
 (define* (make-viewport x y width height #:key
                         (clear-color %default-clear-color)
                         (clear-flags %default-clear-flags))
@@ -84,8 +68,7 @@ CLEAR-FLAGS are 'color-buffer', 'depth-buffer', 'accum-buffer', and
                                     (assert-non-negative-integer width)
                                     (assert-non-negative-integer height))
                   clear-color
-                  clear-flags
-                  (clear-buffer-mask clear-flags)))
+                  clear-flags))
 
 (define null-viewport (make-viewport 0 0 0 0))
 
@@ -95,7 +78,7 @@ CLEAR-FLAGS are 'color-buffer', 'depth-buffer', 'accum-buffer', and
                           (clear-color (viewport-clear-color viewport)))
       body ...)))
 
-;; TODO: Add clear buffer mask to managed gpu state.
+;; TODO: Use current viewport's clear flags.
 (define (clear-viewport)
   (graphics-engine-commit! (current-graphics-engine))
-  (gl-clear (clear-buffer-mask %default-clear-flags)))
+  (gpu-clear-viewport %default-clear-flags))
-- 
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