graphics: blend: Add proper <blend-mode> data type.

No more symbols.  Hooray!

5 files changed, 120 insertions, 47 deletions

diff --git a/chickadee/graphics/blend.scm b/chickadee/graphics/blend.scm
index 8901246..d13d541 100644
--- a/chickadee/graphics/blend.scm
+++ b/chickadee/graphics/blend.scm
@@ -16,54 +16,126 @@
 ;;; <http://www.gnu.org/licenses/>.
 
 (define-module (chickadee graphics blend)
-  #:use-module (ice-9 match)
-  #:use-module (gl)
   #:use-module (chickadee graphics engine)
   #:use-module (chickadee graphics gl)
-  #:export (g:blend-mode
+  #:use-module (gl)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-9)
+  #:export (make-blend-mode
+            blend-mode?
+            blend-mode-equation
+            blend-mode-source-function
+            blend-mode-destination-function
+            blend:alpha
+            blend:multiply
+            blend:subtract
+            blend:add
+            blend:lighten
+            blend:darken
+            blend:screen
+            blend:replace
+            g:blend-mode
             current-blend-mode))
 
+(define-record-type <blend-mode>
+  (make-blend-mode equation source-function destination-function)
+  blend-mode?
+  (equation blend-mode-equation)
+  (source-function blend-mode-source-function)
+  (destination-function blend-mode-destination-function))
+
+(define blend:alpha
+  (make-blend-mode 'add 'source-alpha 'one-minus-source-alpha))
+(define blend:multiply
+  (make-blend-mode 'add 'destination-color 'zero))
+(define blend:subtract
+  (make-blend-mode 'reverse-subtract 'one 'zero))
+(define blend:add
+  (make-blend-mode 'add 'one 'one))
+(define blend:lighten
+  (make-blend-mode 'max 'one 'zero))
+(define blend:darken
+  (make-blend-mode 'min 'one 'zero))
+(define blend:screen
+  (make-blend-mode 'add 'one 'one-minus-source-color))
+(define blend:replace
+  (make-blend-mode 'add 'one 'zero))
+
 (define (bind-blend-mode blend-mode)
   (if blend-mode
       (begin
         (gl-enable (enable-cap blend))
-        (match blend-mode
-          ('alpha
-           (gl-blend-equation (blend-equation-mode-ext func-add-ext))
-           (gl-blend-func (blending-factor-src src-alpha)
-                          (blending-factor-dest one-minus-src-alpha)))
-          ('multiply
-           (gl-blend-equation (blend-equation-mode-ext func-add-ext))
-           (gl-blend-func (blending-factor-src dst-color)
-                          (blending-factor-dest zero)))
-          ('subtract
-           (gl-blend-equation
+        (gl-blend-equation
+         (match (blend-mode-equation blend-mode)
+           ('add
+            (blend-equation-mode-ext func-add-ext))
+           ('subtract
+            (blend-equation-mode-ext func-subtract-ext))
+           ('reverse-subtract
             (blend-equation-mode-ext func-reverse-subtract-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest zero)))
-          ('add
-           (gl-blend-equation (blend-equation-mode-ext func-add-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest one)))
-          ('lighten
-           (gl-blend-equation (blend-equation-mode-ext max-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest zero)))
-          ('darken
-           (gl-blend-equation (blend-equation-mode-ext min-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest zero)))
-          ('screen
-           (gl-blend-equation (blend-equation-mode-ext func-add-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest one-minus-src-color)))
-          ('replace
-           (gl-blend-equation (blend-equation-mode-ext func-add-ext))
-           (gl-blend-func (blending-factor-src one)
-                          (blending-factor-dest zero)))))
+           ('min
+            (blend-equation-mode-ext min-ext))
+           ('max
+            (blend-equation-mode-ext max-ext))
+           ('alpha-min
+            (blend-equation-mode-ext alpha-min-sgix))
+           ('alpha-max
+            (blend-equation-mode-ext alpha-min-sgix))))
+        (gl-blend-func (match (blend-mode-source-function blend-mode)
+                         ('zero
+                          (blending-factor-src zero))
+                         ('one
+                          (blending-factor-src one))
+                         ('destination-color
+                          (blending-factor-src dst-color))
+                         ('one-minus-destination-color
+                          (blending-factor-src one-minus-dst-color))
+                         ('source-alpha-saturate
+                          (blending-factor-src src-alpha-saturate))
+                         ('source-alpha
+                          (blending-factor-src src-alpha))
+                         ('one-minus-source-alpha
+                          (blending-factor-src one-minus-src-alpha))
+                         ('destination-alpha
+                          (blending-factor-src dst-alpha))
+                         ('one-minus-destination-alpha
+                          (blending-factor-src one-minus-dst-alpha))
+                         ('constant-color
+                          (blending-factor-src constant-color-ext))
+                         ('one-minus-constant-color
+                          (blending-factor-src one-minus-constant-color-ext))
+                         ('contstant-alpha
+                          (blending-factor-src constant-alpha-ext))
+                         ('one-minus-constant-alpha
+                          (blending-factor-src one-minus-constant-alpha-ext)))
+                       (match (blend-mode-destination-function blend-mode)
+                         ('zero
+                          (blending-factor-dest zero))
+                         ('one
+                          (blending-factor-dest one))
+                         ('source-color
+                          (blending-factor-dest src-color))
+                         ('one-minus-source-color
+                          (blending-factor-dest one-minus-src-color))
+                         ('source-alpha
+                          (blending-factor-dest src-alpha))
+                         ('one-minus-source-alpha
+                          (blending-factor-dest one-minus-src-alpha))
+                         ('destination-alpha
+                          (blending-factor-dest dst-alpha))
+                         ('one-minus-destination-alpha
+                          (blending-factor-dest one-minus-dst-alpha))
+                         ('constant-color
+                          (blending-factor-dest constant-color-ext))
+                         ('one-minus-constant-color
+                          (blending-factor-dest one-minus-constant-color-ext))
+                         ('contstant-alpha
+                          (blending-factor-dest constant-alpha-ext))
+                         ('one-minus-constant-alpha
+                          (blending-factor-dest one-minus-constant-alpha-ext)))))
       (gl-disable (enable-cap blend))))
 
 (define-graphics-state g:blend-mode
   current-blend-mode
-  #:default 'replace
+  #:default blend:replace
   #:bind bind-blend-mode)
diff --git a/chickadee/graphics/font.scm b/chickadee/graphics/font.scm
index eb1de3f..8adba8d 100644
--- a/chickadee/graphics/font.scm
+++ b/chickadee/graphics/font.scm
@@ -37,6 +37,7 @@
   #:use-module (chickadee math matrix)
   #:use-module (chickadee math rect)
   #:use-module (chickadee math vector)
+  #:use-module (chickadee graphics blend)
   #:use-module (chickadee graphics color)
   #:use-module (chickadee graphics engine)
   #:use-module (chickadee graphics shader)
@@ -433,7 +434,7 @@ extension must be either .xml or .fnt."
 (define draw-text*
   (let ((cursor (vec2 0.0 0.0))
         (rect (make-rect 0.0 0.0 0.0 0.0)))
-    (lambda* (font text matrix #:key (blend-mode 'alpha)
+    (lambda* (font text matrix #:key (blend-mode blend:alpha)
                    (color white) (start 0) (end (string-length text)))
       (let ((batches (font-sprite-batches font))
             (kernings (font-kernings font)))
@@ -500,7 +501,7 @@ extension must be either .xml or .fnt."
               (origin %null-vec2)
               (rotation 0)
               (scale %default-scale)
-              (blend-mode 'alpha)
+              (blend-mode blend:alpha)
               (start 0)
               (end (string-length text)))
       "Draw the string TEXT with the first character starting at
diff --git a/chickadee/graphics/particles.scm b/chickadee/graphics/particles.scm
index d735572..08e5957 100644
--- a/chickadee/graphics/particles.scm
+++ b/chickadee/graphics/particles.scm
@@ -204,7 +204,7 @@ void main (void) {
                            (delete emitter (particles-emitters particles))))
 
 (define* (make-particles capacity #:key
-                         (blend-mode 'alpha)
+                         (blend-mode blend:alpha)
                          (start-color white)
                          (end-color (make-color 0.0 0.0 0.0 0.0))
                          (texture null-texture)
diff --git a/chickadee/graphics/path.scm b/chickadee/graphics/path.scm
index 8a4edfd..ef5206a 100644
--- a/chickadee/graphics/path.scm
+++ b/chickadee/graphics/path.scm
@@ -1194,7 +1194,7 @@
   ;; Another mini VM for a simple picture language.
   (let loop ((commands (painter-commands painter))
              (matrix matrix)
-             (blend-mode 'alpha)
+             (blend-mode blend:alpha)
              (fill-color white)
              (stroke-color black)
              (stroke-width 1.0)
diff --git a/chickadee/graphics/sprite.scm b/chickadee/graphics/sprite.scm
index 76ee94a..0d6f838 100644
--- a/chickadee/graphics/sprite.scm
+++ b/chickadee/graphics/sprite.scm
@@ -108,7 +108,7 @@ void main (void) {
                        matrix
                        #:key
                        (tint white)
-                       (blend-mode 'alpha)
+                       (blend-mode blend:alpha)
                        (texcoords (texture-gl-tex-rect texture)))
   (let ((shader (graphics-variable-ref sprite-shader))
         (geometry (graphics-variable-ref sprite-geometry))
@@ -152,7 +152,7 @@ void main (void) {
                       (origin %null-vec2)
                       (scale %default-scale)
                       (rotation 0.0)
-                      (blend-mode 'alpha)
+                      (blend-mode blend:alpha)
                       (rect (texture-gl-rect texture)))
   "Draw TEXTURE at POSITION.
 
@@ -335,7 +335,7 @@ may be specified via the TEXTURE-REGION argument."
                        #:tint tint
                        #:texture-region texture-region)))
 
-(define* (draw-sprite-batch* batch matrix #:key (blend-mode 'alpha))
+(define* (draw-sprite-batch* batch matrix #:key (blend-mode blend:alpha))
   "Render the contents of BATCH."
   (let ((shader (graphics-variable-ref sprite-batch-shader))
         (mvp (graphics-variable-ref sprite-mvp-matrix)))
@@ -356,7 +356,7 @@ may be specified via the TEXTURE-REGION argument."
                             (origin %null-vec2)
                             (scale %default-scale)
                             (rotation 0.0)
-                            (blend-mode 'alpha))
+                            (blend-mode blend:alpha))
   "Render the contents of BATCH."
   (let ((matrix (graphics-variable-ref sprite-model-matrix)))
     (matrix4-2d-transform! matrix
@@ -383,7 +383,7 @@ may be specified via the TEXTURE-REGION argument."
               (bottom-margin margin)
               (left-margin margin)
               (right-margin margin)
-              (blend-mode 'alpha)
+              (blend-mode blend:alpha)
               (tint white))
       (let* ((x (rect-x rect))
              (y (rect-y rect))
@@ -463,7 +463,7 @@ may be specified via the TEXTURE-REGION argument."
               (origin %null-vec2)
               (rotation 0.0)
               (scale %default-scale)
-              (blend-mode 'alpha)
+              (blend-mode blend:alpha)
               (tint white))
       "Draw a \"nine patch\" sprite.  A nine patch sprite renders
 TEXTURE on the rectangular area RECT whose stretchable areas are