From 8c6326a46f82ae46cc63bd431b0678d4f6b10d00 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 16 Aug 2021 17:11:28 -0400
Subject: graphics: shader: Add support for cube map samplers.

---
 chickadee/graphics/shader.scm | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/chickadee/graphics/shader.scm b/chickadee/graphics/shader.scm
index 80acd02..08e8672 100644
--- a/chickadee/graphics/shader.scm
+++ b/chickadee/graphics/shader.scm
@@ -47,6 +47,7 @@
             float-vec4
             mat4
             sampler-2d
+            sampler-cube
             local-field
             define-shader-type
             uniform-namespace?
@@ -236,6 +237,16 @@
   #:setter gl-uniform1iv
   #:null 0)
 
+(define-shader-primitive-type sampler-cube
+  #:name 'sampler-cube
+  #:size 4
+  #:validator integer?
+  #:serializer
+  (lambda (bv i texture-unit)
+    (bytevector-s32-native-set! bv i texture-unit))
+  #:setter gl-uniform1iv
+  #:null 0)
+
 
 ;;;
 ;;; Compound Shader Data Types
@@ -579,6 +590,7 @@ them into a GPU shader program."
      ((= type (version-2-0 float-vec4)) float-vec4)
      ((= type (version-2-0 float-mat4)) mat4)
      ((= type (version-2-0 sampler-2d)) sampler-2d)
+     ((= type (version-2-0 sampler-cube)) sampler-cube)
      (else
       (error "unsupported OpenGL type" type))))
   (define (camel->snake str)
@@ -660,7 +672,7 @@ them into a GPU shader program."
                      (location (gl-get-uniform-location id name))
                      (size (u32vector-ref size-bv 0))
                      (type (parse-data-type (u32vector-ref type-bv 0)))
-                     (sampler? (eq? type sampler-2d))
+                     (sampler? (or (eq? type sampler-2d) (eq? type sampler-cube)))
                      (default (cond
                                (sampler?
                                 texture-unit)
@@ -815,7 +827,8 @@ shader program."
              ;; most other values.  In the case of samplers, they are
              ;; mapped to OpenGL's "texture units", so we need to
              ;; ignore them here.
-             (unless (eq? (uniform-type uniform) sampler-2d)
+             (unless (or (eq? (uniform-type uniform) sampler-2d)
+                         (eq? (uniform-type uniform) sampler-cube))
                (traverse uniform (shader-struct-ref value key))))
            uniform)
           (error "expected shader struct" x)))
@@ -854,7 +867,8 @@ shader program."
     ;; behind the scenes.
     (shader-uniform-for-each
      (lambda (uniform)
-       (when (eq? (uniform-type uniform) sampler-2d)
+       (when (or (eq? (uniform-type uniform) sampler-2d)
+                 (eq? (uniform-type uniform) sampler-cube))
          (set-uniform-value! shader* uniform (uniform-value uniform))))
      shader*)
     exp))
-- 
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