render: Add stencil test support.

5 files changed, 158 insertions, 1 deletions

diff --git a/Makefile.am b/Makefile.am
index d8e0314..5cd42b5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -65,6 +65,7 @@ SOURCES = 					\
   chickadee/render/gpu.scm			\
   chickadee/render/blend.scm			\
   chickadee/render/depth.scm			\
+  chickadee/render/stencil.scm			\
   chickadee/render/texture.scm			\
   chickadee/render/shader.scm			\
   chickadee/render/buffer.scm			\
diff --git a/chickadee/render/gl.scm b/chickadee/render/gl.scm
index 67d8ef1..0781048 100644
--- a/chickadee/render/gl.scm
+++ b/chickadee/render/gl.scm
@@ -316,3 +316,14 @@ object.")
            (%glDepthMask . gl-depth-mask)
            (%glDepthRange . gl-depth-range))
 
+
+;;;
+;;; Stencil Buffer
+;;;
+
+(re-export (%glStencilMask . gl-stencil-mask)
+           (%glStencilMaskSeparate . gl-stencil-mask-separate)
+           (%glStencilFunc . gl-stencil-func)
+           (%glStencilFuncSeparate . gl-stencil-func-separate)
+           (%glStencilOp . gl-stencil-op)
+           (%glStencilOpSeparate . gl-stencil-op-separate))
diff --git a/chickadee/render/gpu.scm b/chickadee/render/gpu.scm
index 3974c68..e01486d 100644
--- a/chickadee/render/gpu.scm
+++ b/chickadee/render/gpu.scm
@@ -37,6 +37,7 @@
             gpu-glsl-version
             gpu-blend-mode
             gpu-depth-test
+            gpu-stencil-test
             gpu-framebuffer
             gpu-shader
             gpu-texture
@@ -45,6 +46,7 @@
             gpu-viewport
             set-gpu-blend-mode!
             set-gpu-depth-test!
+            set-gpu-stencil-test!
             set-gpu-framebuffer!
             set-gpu-shader!
             set-gpu-texture!
@@ -100,6 +102,7 @@ from the GPU's memory."
              glsl-version
              blend-mode
              depth-test
+             stencil-test
              framebuffer
              shader
              textures
@@ -112,6 +115,7 @@ from the GPU's memory."
   (glsl-version gpu-glsl-version)
   (blend-mode %gpu-blend-mode)
   (depth-test %gpu-depth-test)
+  (stencil-test %gpu-stencil-test)
   (framebuffer %gpu-framebuffer)
   (shader %gpu-shader)
   (textures gpu-textures)
@@ -128,6 +132,7 @@ from the GPU's memory."
         ;; Lazily resolve bindings to avoid circular dependencies.
         (blend-module (resolve-interface '(chickadee render blend)))
         (depth-module (resolve-interface '(chickadee render depth)))
+        (stencil-module (resolve-interface '(chickadee render stencil)))
         (buffer-module (resolve-interface '(chickadee render buffer)))
         (framebuffer-module (resolve-interface '(chickadee render framebuffer)))
         (shader-module (resolve-interface '(chickadee render shader)))
@@ -150,6 +155,7 @@ from the GPU's memory."
                (make-gpu-state (module-ref blend-module 'apply-blend-mode)
                                'replace)
                (make-gpu-state (module-ref depth-module 'apply-depth-test) #f)
+               (make-gpu-state (module-ref stencil-module 'apply-stencil-test) #f)
                (make-gpu-state (module-ref framebuffer-module 'apply-framebuffer)
                                (module-ref framebuffer-module 'null-framebuffer))
                (make-gpu-state (module-ref shader-module 'apply-shader)
@@ -168,6 +174,7 @@ from the GPU's memory."
 
 (define-gpu-getter gpu-blend-mode %gpu-blend-mode)
 (define-gpu-getter gpu-depth-test %gpu-depth-test)
+(define-gpu-getter gpu-stencil-test %gpu-stencil-test)
 (define-gpu-getter gpu-framebuffer %gpu-framebuffer)
 (define-gpu-getter gpu-shader %gpu-shader)
 (define-gpu-getter gpu-vertex-buffer %gpu-vertex-buffer)
@@ -180,6 +187,7 @@ from the GPU's memory."
 
 (define-gpu-setter set-gpu-blend-mode! %gpu-blend-mode)
 (define-gpu-setter set-gpu-depth-test! %gpu-depth-test)
+(define-gpu-setter set-gpu-stencil-test! %gpu-stencil-test)
 (define-gpu-setter set-gpu-framebuffer! %gpu-framebuffer)
 (define-gpu-setter set-gpu-shader! %gpu-shader)
 (define-gpu-setter set-gpu-vertex-buffer! %gpu-vertex-buffer)
diff --git a/chickadee/render/stencil.scm b/chickadee/render/stencil.scm
new file mode 100644
index 0000000..4a20300
--- /dev/null
+++ b/chickadee/render/stencil.scm
@@ -0,0 +1,137 @@
+;;; Chickadee Game Toolkit
+;;; Copyright © 2020 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/>.
+
+(define-module (chickadee render stencil)
+  #:use-module (ice-9 match)
+  #:use-module (gl)
+  #:use-module (chickadee render gl)
+  #:use-module (chickadee render gpu)
+  #:use-module (srfi srfi-9)
+  #:export (make-stencil-test
+            stencil-test?
+            stencil-test-mask-front
+            stencil-test-mask-back
+            stencil-test-function-front
+            stencil-test-function-back
+            stencil-test-function-mask-front
+            stencil-test-function-mask-back
+            stencil-test-reference-front
+            stencil-test-reference-back
+            stencil-test-on-fail-front
+            stencil-test-on-fail-back
+            stencil-test-on-depth-fail-front
+            stencil-test-on-depth-fail-back
+            stencil-test-on-pass-front
+            stencil-test-on-pass-back
+            default-stencil-test
+            apply-stencil-test))
+
+(define-record-type <stencil-test>
+  (%make-stencil-test mask-front mask-back function-front function-back
+                      function-mask-front function-mask-back
+                      reference-front reference-back
+                      on-fail-front on-fail-back
+                      on-depth-fail-front on-depth-fail-back
+                      on-pass-front on-pass-back)
+  stencil-test?
+  (mask-front stencil-test-mask-front)
+  (mask-back stencil-test-mask-back)
+  (function-front stencil-test-function-front)
+  (function-back stencil-test-function-back)
+  (function-mask-front stencil-test-function-mask-front)
+  (function-mask-back stencil-test-function-mask-back)
+  (reference-front stencil-test-reference-front)
+  (reference-back stencil-test-reference-back)
+  (on-fail-front stencil-test-on-fail-front)
+  (on-fail-back stencil-test-on-fail-back)
+  (on-depth-fail-front stencil-test-on-depth-fail-front)
+  (on-depth-fail-back stencil-test-on-depth-fail-back)
+  (on-pass-front stencil-test-on-pass-front)
+  (on-pass-back stencil-test-on-pass-back))
+
+(define* (make-stencil-test #:key (mask #xFF) (function 'always)
+                            (function-mask #xFF) (reference 0)
+                            (on-fail 'keep) (on-depth-fail 'keep) (on-pass 'keep)
+                            (mask-front mask) (mask-back mask)
+                            (function-front function) (function-back function)
+                            (function-mask-front function-mask)
+                            (function-mask-back function-mask)
+                            (reference-front reference)
+                            (reference-back reference)
+                            (on-fail-front on-fail) (on-fail-back on-fail)
+                            (on-depth-fail-front on-depth-fail)
+                            (on-depth-fail-back on-depth-fail)
+                            (on-pass-front on-pass) (on-pass-back on-pass))
+  (%make-stencil-test mask-front mask-back function-front function-back
+                      function-mask-front function-mask-back
+                      reference-front reference-back
+                      on-fail-front on-fail-back
+                      on-depth-fail-front on-depth-fail-back
+                      on-pass-front on-pass-back))
+
+(define %default-stencil-test (make-stencil-test))
+
+(define* (apply-stencil-test stencil)
+  (define (symbol->op sym)
+    (match sym
+      ('zero (stencil-op zero))
+      ('keep (stencil-op keep))
+      ('replace (stencil-op replace))
+      ('increment (stencil-op incr))
+      ('increment-wrap (version-1-4 incr-wrap))
+      ('decrement (stencil-op decr))
+      ('decrement-wrap (version-1-4 decr-wrap))
+      ('invert (stencil-op invert))))
+  (define (symbol->function sym)
+    (match sym
+      ('always (stencil-function always))
+      ('never (stencil-function never))
+      ('less-than (stencil-function less))
+      ('equal (stencil-function equal))
+      ('less-than-or-equal (stencil-function lequal))
+      ('greater-than (stencil-function greater))
+      ('greater-than-or-equal (stencil-function gequal))
+      ('not-equal (stencil-function notequal))))
+  (if stencil
+      (begin
+        (gl-enable (enable-cap stencil-test))
+        ;; Mask
+        (gl-stencil-mask-separate (cull-face-mode front)
+                                  (stencil-test-mask-front stencil))
+        (gl-stencil-mask-separate (cull-face-mode back)
+                                  (stencil-test-mask-back stencil))
+        ;; Function
+        (gl-stencil-func-separate (cull-face-mode front)
+                                  (symbol->function
+                                   (stencil-test-function-front stencil))
+                                  (stencil-test-reference-front stencil)
+                                  (stencil-test-function-mask-front stencil))
+        (gl-stencil-func-separate (cull-face-mode back)
+                                  (symbol->function
+                                   (stencil-test-function-back stencil))
+                                  (stencil-test-reference-back stencil)
+                                  (stencil-test-function-mask-back stencil))
+        ;; Operation
+        (gl-stencil-op-separate (cull-face-mode front)
+                                (symbol->op (stencil-test-on-fail-front stencil))
+                                (symbol->op (stencil-test-on-depth-fail-front stencil))
+                                (symbol->op (stencil-test-on-pass-front stencil)))
+        (gl-stencil-op-separate (cull-face-mode back)
+                                (symbol->op (stencil-test-on-fail-back stencil))
+                                (symbol->op (stencil-test-on-depth-fail-back stencil))
+                                (symbol->op (stencil-test-on-pass-back stencil))))
+      (gl-disable (enable-cap stencil-test))))
diff --git a/chickadee/render/viewport.scm b/chickadee/render/viewport.scm
index 91f50c1..7b9a192 100644
--- a/chickadee/render/viewport.scm
+++ b/chickadee/render/viewport.scm
@@ -53,7 +53,7 @@
   (clear-color viewport-clear-color)
   (clear-flags viewport-clear-flags))
 
-(define %default-clear-flags '(color-buffer depth-buffer))
+(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)