graphics: Add multisampling support.

3 files changed, 34 insertions, 5 deletions

diff --git a/chickadee.scm b/chickadee.scm
index e974b9f..ad018be 100644
--- a/chickadee.scm
+++ b/chickadee.scm
@@ -241,6 +241,8 @@ border is disabled, otherwise it is enabled.")
   (sdl2:set-gl-attribute! 'context-major-version 2)
   (sdl2:set-gl-attribute! 'context-profile-mask 1) ; core profile
   (sdl2:set-gl-attribute! 'stencil-size 8) ; 8-bit stencil buffer
+  (sdl2:set-gl-attribute! 'multisample-buffers 1)
+  (sdl2:set-gl-attribute! 'multisample-samples 4)
   (let* ((window (sdl2:make-window #:opengl? #t
                                    #:title window-title
                                    #:size (list window-width window-height)
@@ -350,6 +352,8 @@ border is disabled, otherwise it is enabled.")
             (lambda args
               (display "warning: could not enable vsync\n"
                        (current-error-port))))
+          ;; Turn off multisampling by default.
+          (gl-disable (version-1-3 multisample))
           (load)
           (sdl2:load-game-controller-mappings!
            (scope-datadir "gamecontrollerdb.txt"))
diff --git a/chickadee/graphics.scm b/chickadee/graphics.scm
index 4cc21a4..bfa1139 100644
--- a/chickadee/graphics.scm
+++ b/chickadee/graphics.scm
@@ -38,6 +38,7 @@
             current-stencil-test
             current-texture
             current-projection
+            current-multisample
             with-viewport
             with-framebuffer
             with-blend-mode
@@ -45,6 +46,7 @@
             with-stencil-test
             with-texture
             with-projection
+            with-multisample
             clear-screen
             gpu-apply
             gpu-apply*
@@ -53,7 +55,7 @@
 
 (define-record-type <render-context>
   (make-render-context viewport framebuffer blend-mode depth-test
-                       stencil-test projection textures)
+                       stencil-test projection multisample? textures)
   render-context?
   (viewport render-context-viewport set-render-context-viewport!)
   (framebuffer render-context-framebuffer set-render-context-framebuffer!)
@@ -61,6 +63,7 @@
   (depth-test render-context-depth-test set-render-context-depth-test!)
   (stencil-test render-context-stencil-test set-render-context-stencil-test!)
   (projection render-context-projection set-render-context-projection!)
+  (multisample? render-context-multisample? set-render-context-multisample!)
   (textures render-context-textures))
 
 (define render-context
@@ -70,6 +73,7 @@
                        #f
                        #f
                        (make-identity-matrix4)
+                       #f
                        (make-vector 32 null-texture)))
 
 (define (current-viewport)
@@ -93,6 +97,9 @@
 (define (current-projection)
   (render-context-projection render-context))
 
+(define (current-multisample)
+  (render-context-multisample? render-context))
+
 (define-syntax-rule (with (getter setter value) body ...)
   (let ((prev (getter render-context)))
     (setter render-context value)
@@ -143,6 +150,10 @@
   (with (render-context-projection set-render-context-projection! matrix)
         body ...))
 
+(define-syntax-rule (with-multisample multisample? body ...)
+  (with (render-context-multisample? set-render-context-multisample! multisample?)
+        body ...))
+
 (define (keyword->string kw)
   (symbol->string (keyword->symbol kw)))
 
@@ -167,6 +178,7 @@
     (set-gpu-blend-mode! gpu (current-blend-mode))
     (set-gpu-depth-test! gpu (current-depth-test))
     (set-gpu-stencil-test! gpu (current-stencil-test))
+    (set-gpu-multisample! gpu (current-multisample))
     (set-gpu-shader! gpu shader)
     (let loop ((i 0))
       (when (< i 32)
diff --git a/chickadee/graphics/gpu.scm b/chickadee/graphics/gpu.scm
index b8c8ca5..7a70d7e 100644
--- a/chickadee/graphics/gpu.scm
+++ b/chickadee/graphics/gpu.scm
@@ -17,6 +17,7 @@
 
 (define-module (chickadee graphics gpu)
   #:use-module (chickadee graphics gl)
+  #:use-module (gl)
   #:use-module (gl enums)
   #:use-module (oop goops)
   #:use-module (srfi srfi-9)
@@ -45,6 +46,7 @@
             gpu-vertex-buffer
             gpu-vertex-array
             gpu-viewport
+            gpu-multisample
             set-gpu-blend-mode!
             set-gpu-depth-test!
             set-gpu-stencil-test!
@@ -53,7 +55,8 @@
             set-gpu-texture!
             set-gpu-vertex-buffer!
             set-gpu-vertex-array!
-            set-gpu-viewport!))
+            set-gpu-viewport!
+            set-gpu-multisample!))
 
 
 ;;;
@@ -110,7 +113,8 @@ from the GPU's memory."
              textures
              vertex-buffer
              vertex-array
-             viewport)
+             viewport
+             multisample)
   gpu?
   (gl-context gpu-gl-context)
   (gl-version gpu-gl-version)
@@ -124,7 +128,8 @@ from the GPU's memory."
   (textures gpu-textures)
   (vertex-buffer %gpu-vertex-buffer)
   (vertex-array %gpu-vertex-array)
-  (viewport %gpu-viewport))
+  (viewport %gpu-viewport)
+  (multisample %gpu-multisample))
 
 (define current-gpu (make-parameter #f))
 
@@ -134,6 +139,11 @@ from the GPU's memory."
                       (bytevector->pointer bv))
     (s32vector-ref bv 0)))
 
+(define (apply-multisample multisample?)
+  (if multisample?
+      (gl-enable (version-1-3 multisample))
+      (gl-disable (version-1-3 multisample))))
+
 (define (make-gpu gl-context)
   (define (extract-version attr)
     (car (string-split (pointer->string (gl-get-string attr)) #\space)))
@@ -176,7 +186,8 @@ from the GPU's memory."
                (make-gpu-state (module-ref buffer-module 'apply-vertex-array)
                                (module-ref buffer-module 'null-vertex-array))
                (make-gpu-state (module-ref viewport-module 'apply-viewport)
-                               (module-ref viewport-module 'null-viewport)))))
+                               (module-ref viewport-module 'null-viewport))
+               (make-gpu-state apply-multisample #f))))
 
 (define-syntax-rule (define-gpu-getter name ref)
   (define (name gpu)
@@ -190,6 +201,7 @@ from the GPU's memory."
 (define-gpu-getter gpu-vertex-buffer %gpu-vertex-buffer)
 (define-gpu-getter gpu-vertex-array %gpu-vertex-array)
 (define-gpu-getter gpu-viewport %gpu-viewport)
+(define-gpu-getter gpu-multisample %gpu-multisample)
 
 (define-syntax-rule (define-gpu-setter name ref)
   (define (name gpu x)
@@ -203,6 +215,7 @@ from the GPU's memory."
 (define-gpu-setter set-gpu-vertex-buffer! %gpu-vertex-buffer)
 (define-gpu-setter set-gpu-vertex-array! %gpu-vertex-array)
 (define-gpu-setter set-gpu-viewport! %gpu-viewport)
+(define-gpu-setter set-gpu-multisample! %gpu-multisample)
 
 (define (gpu-texture gpu texture-unit)
   (gpu-state-ref (vector-ref (gpu-textures gpu) texture-unit)))