diff options
| -rw-r--r-- | sly/render/utils.scm | 59 |
1 files changed, 58 insertions, 1 deletions
diff --git a/sly/render/utils.scm b/sly/render/utils.scm index a0748b2..24d1180 100644 --- a/sly/render/utils.scm +++ b/sly/render/utils.scm @@ -23,7 +23,64 @@ (define-module (sly render utils) #:use-module (oop goops) - #:export (draw)) + #:use-module (ice-9 match) + #:use-module (srfi srfi-9) + #:use-module (gl low-level) + #:use-module (gl enums) + #:export (draw + make-blend-mode blend-mode? + blend-mode-source blend-mode-destination + default-blend-mode + apply-blend-mode)) ;; Generic method for rendering objects. (define-generic draw) + +;;; +;;; Blending +;;; + +(define-record-type <blend-mode> + (make-blend-mode source destination) + blend-mode? + (source blend-mode-source) + (destination blend-mode-destination)) + +(define default-blend-mode + (make-blend-mode 'src-alpha 'one-minus-src-alpha)) + +;; Translate symbols to OpenGL constants. +(define source-blend-function + (match-lambda + ('zero 0) + ('one 1) + ('dst-color 774) + ('one-minus-dst-color 775) + ('src-alpha-saturate 776) + ('src-alpha 770) + ('one-minus-src-alpha 771) + ('dst-alpha 772) + ('one-minus-dst-alpha 773) + ('constant-color 32769) + ('one-minus-constant-color 32770) + ('constant-alpha 32771) + ('one-minus-constant-alpha 32772))) + +(define destination-blend-function + (match-lambda + ('zero 0) + ('one 1) + ('src-color 768) + ('one-minus-src-color 769) + ('src-alpha 770) + ('one-minus-src-alpha 771) + ('dst-alpha 772) + ('one-minus-dst-alpha 773) + ('constant-color 32769) + ('one-minus-constant-color 32770) + ('constant-alpha 32771) + ('one-minus-constant-alpha 32772))) + +(define (apply-blend-mode blend-mode) + (glBlendFunc (source-blend-function (blend-mode-source blend-mode)) + (destination-blend-function (blend-mode-destination blend-mode)))) |