From 2fe872f0f5b6b07cd18790d53384413ffd480c4f Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Thu, 14 Sep 2023 19:54:00 -0400
Subject: graphics: Factor out GL calls in framebuffer module.

---
 chickadee/graphics/framebuffer.scm | 35 ++++-------------------------------
 chickadee/graphics/gpu.scm         | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/chickadee/graphics/framebuffer.scm b/chickadee/graphics/framebuffer.scm
index f4f3100..2af7edd 100644
--- a/chickadee/graphics/framebuffer.scm
+++ b/chickadee/graphics/framebuffer.scm
@@ -23,12 +23,9 @@
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-9)
   #:use-module (system foreign)
-  #:use-module (gl)
-  #:use-module (gl enums)
   #:use-module (chickadee math matrix)
   #:use-module (chickadee graphics color)
   #:use-module (chickadee graphics engine)
-  #:use-module (chickadee graphics gl)
   #:use-module (chickadee graphics gpu)
   #:use-module (chickadee graphics pixbuf)
   #:use-module ((chickadee graphics texture) #:select (make-texture null-texture))
@@ -39,7 +36,6 @@
             framebuffer-viewport
             framebuffer-projection
             null-framebuffer
-            g:framebuffer
             current-framebuffer
             with-framebuffer))
 
@@ -56,7 +52,6 @@
   (%make-framebuffer 0 0 null-texture null-viewport (make-identity-matrix4)))
 
 (define %clear-color (transparency 0.0))
-(define %draw-buffers (bytevector->pointer (u32vector (version-3-0 color-attachment0))))
 
 (define* (make-framebuffer width height #:key (min-filter 'linear) (mag-filter 'linear)
                            (wrap-s 'repeat) (wrap-t 'repeat))
@@ -71,6 +66,8 @@ dimensions WIDTH x HEIGHT."
                                 #:mag-filter mag-filter
                                 #:wrap-s wrap-s
                                 #:wrap-t wrap-t))
+         (texture-id ((@@ (chickadee graphics texture) texture-id)
+                      texture))
          ;; It is convenient to make a default viewport and
          ;; projection matrix for the framebuffer so that the
          ;; rendering engine can set it whenever it changes to
@@ -83,32 +80,8 @@ dimensions WIDTH x HEIGHT."
                                          texture
                                          viewport
                                          projection)))
-    (set-gpu-renderbuffer! gpu renderbuffer-id)
-    (set-gpu-framebuffer! gpu framebuffer-id)
-    ;; Setup depth buffer.
-    (gl-bind-renderbuffer (version-3-0 renderbuffer)
-                          renderbuffer-id)
-    (gl-renderbuffer-storage (version-3-0 renderbuffer)
-                             (arb-framebuffer-object depth24-stencil8)
-                             width
-                             height)
-    (gl-bind-renderbuffer (version-3-0 renderbuffer) 0)
-    (gl-framebuffer-renderbuffer (version-3-0 framebuffer)
-                                 (arb-framebuffer-object depth-stencil-attachment)
-                                 (version-3-0 renderbuffer)
-                                 renderbuffer-id)
-    ;; Setup framebuffer.
-    (gl-framebuffer-texture-2d (version-3-0 framebuffer)
-                               (version-3-0 color-attachment0)
-                               (texture-target texture-2d)
-                               ((@@ (chickadee graphics texture) texture-id)
-                                texture)
-                               0)
-    (gl-draw-buffers 1 %draw-buffers)
-    ;; Check for errors.
-    (unless (= (gl-check-framebuffer-status (version-3-0 framebuffer))
-               (version-3-0 framebuffer-complete))
-      (error "Framebuffer cannot be created"))
+    (gpu-framebuffer-init gpu framebuffer-id renderbuffer-id texture-id
+                          width height)
     framebuffer))
 
 (define-syntax-rule (with-framebuffer framebuffer body ...)
diff --git a/chickadee/graphics/gpu.scm b/chickadee/graphics/gpu.scm
index 93aac87..ef12d10 100644
--- a/chickadee/graphics/gpu.scm
+++ b/chickadee/graphics/gpu.scm
@@ -113,6 +113,7 @@
             free-gpu-framebuffer
             gpu-framebuffer?
             gpu-framebuffer-id
+            gpu-framebuffer-init
             gpu-framebuffer:null
 
             fresh-gpu-renderbuffer
@@ -1132,6 +1133,34 @@
   (set-active-texture-unit! 0)
   (gl-generate-mipmap (gpu-texture-target texture)))
 
+(define %draw-buffers
+  (bytevector->pointer (u32vector (version-3-0 color-attachment0))))
+
+(define (gpu-framebuffer-init gpu framebuffer renderbuffer texture width height)
+  (set-gpu-framebuffer! gpu framebuffer)
+  ;; Setup depth buffer.
+  (set-gpu-renderbuffer! gpu renderbuffer)
+  (gl-renderbuffer-storage (version-3-0 renderbuffer)
+                           (arb-framebuffer-object depth24-stencil8)
+                           width
+                           height)
+  (set-gpu-renderbuffer! gpu gpu-renderbuffer:null)
+  (gl-framebuffer-renderbuffer (version-3-0 framebuffer)
+                               (arb-framebuffer-object depth-stencil-attachment)
+                               (version-3-0 renderbuffer)
+                               renderbuffer)
+  ;; Setup framebuffer texture.
+  (gl-framebuffer-texture-2d (version-3-0 framebuffer)
+                             (version-3-0 color-attachment0)
+                             (texture-target texture-2d)
+                             (gpu-texture-id texture)
+                             0)
+  (gl-draw-buffers 1 %draw-buffers)
+  ;; Check for errors.
+  (unless (= (gl-check-framebuffer-status (version-3-0 framebuffer))
+             (version-3-0 framebuffer-complete))
+    (error "Framebuffer cannot be created")))
+
 (define (gpu-buffer-upload gpu buffer usage data length offset)
   (set-gpu-buffer! gpu buffer)
   (gl-buffer-data (gpu-buffer-target buffer)
-- 
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