diff options
author | David Thompson <dthompson2@worcester.edu> | 2020-10-03 22:29:27 -0400 |
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committer | David Thompson <dthompson2@worcester.edu> | 2020-10-03 22:29:27 -0400 |
commit | 85c32e4c1302a3c37a1ebb4cf7b4888affdc4f61 (patch) | |
tree | 49405ce1598633857b69e6c8a30ae7abca324173 /chickadee/graphics/viewport.scm | |
parent | 0a13a8e9760091031986fe3a429645113dd038b1 (diff) |
Rename 'render' subdirectory to 'graphics'.
Diffstat (limited to 'chickadee/graphics/viewport.scm')
-rw-r--r-- | chickadee/graphics/viewport.scm | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/chickadee/graphics/viewport.scm b/chickadee/graphics/viewport.scm new file mode 100644 index 0000000..5fd2e9b --- /dev/null +++ b/chickadee/graphics/viewport.scm @@ -0,0 +1,111 @@ +;;; Chickadee Game Toolkit +;;; Copyright © 2017 David Thompson <davet@gnu.org> +;;; +;;; Chickadee is free software: you can redistribute it and/or modify +;;; it under the terms of the GNU General Public License as published +;;; by the Free Software Foundation, either version 3 of the License, +;;; or (at your option) any later version. +;;; +;;; Chickadee is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +;;; General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with this program. If not, see +;;; <http://www.gnu.org/licenses/>. + +;;; Commentary: +;; +;; Viewports specify the renderable section of a window. +;; +;;; Code: + +(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 gl) + #:use-module (chickadee graphics gpu) + #:export (make-viewport + viewport? + viewport-x + viewport-y + viewport-width + viewport-height + viewport-clear-color + viewport-clear-flags + null-viewport + apply-viewport + clear-viewport + %default-clear-flags + %default-clear-color)) + +(define-record-type <viewport> + (%make-viewport x y width height clear-color clear-flags) + viewport? + (x viewport-x) + (y viewport-y) + (width viewport-width) + (height viewport-height) + (clear-color viewport-clear-color) + (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 +;; boring old black. +(define %default-clear-color tango-light-sky-blue) + +(define (assert-non-negative-integer n) + (if (and (integer? n) (>= n 0)) + n + (error "expecting non-negative integer:" n))) + +(define* (make-viewport x y width height #:key + (clear-color %default-clear-color) + (clear-flags %default-clear-flags)) + "Create a viewport that covers an area of the window starting from +coordinates (X, Y) and spanning WIDTH x HEIGHT pixels. Fill the +viewport with CLEAR-COLOR when clearing the screen. Clear the buffers +denoted by the list of symbols in CLEAR-FLAGS. Possible values for +CLEAR-FLAGS are 'color-buffer', 'depth-buffer', 'accum-buffer', and +'stencil-buffer'." + (%make-viewport (assert-non-negative-integer x) + (assert-non-negative-integer y) + (assert-non-negative-integer width) + (assert-non-negative-integer height) + clear-color + clear-flags)) + +(define null-viewport (make-viewport 0 0 0 0)) + +(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 (clear-viewport viewport) + (gl-clear (clear-buffer-mask (viewport-clear-flags viewport)))) + +(define (apply-viewport viewport) + "Set the OpenGL state for VIEWPORT. Clip rendering to the viewport +area, set the clear color, and clear necessary buffers." + (unless (eq? viewport null-viewport) + (let ((x (viewport-x viewport)) + (y (viewport-y viewport)) + (w (viewport-width viewport)) + (h (viewport-height viewport)) + (c (viewport-clear-color viewport))) + (gl-enable (enable-cap scissor-test)) + (gl-viewport x y w h) + (gl-scissor x y w h) + (gl-clear-color (color-r c) (color-g c) (color-b c) (color-a c))))) |