render: Expand depth testing support.

Now includes depth function, mask, and range configuration.

7 files changed, 82 insertions, 15 deletions

diff --git a/Makefile.am b/Makefile.am
index ce67cd0..d8e0314 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -64,6 +64,7 @@ SOURCES = 					\
   chickadee/render/gl.scm			\
   chickadee/render/gpu.scm			\
   chickadee/render/blend.scm			\
+  chickadee/render/depth.scm			\
   chickadee/render/texture.scm			\
   chickadee/render/shader.scm			\
   chickadee/render/buffer.scm			\
diff --git a/chickadee/render.scm b/chickadee/render.scm
index 00e484c..195529d 100644
--- a/chickadee/render.scm
+++ b/chickadee/render.scm
@@ -50,13 +50,13 @@
             gpu-apply/instanced))
 
 (define-record-type <render-context>
-  (make-render-context viewport framebuffer blend-mode depth-test?
-                        projection textures)
+  (make-render-context viewport framebuffer blend-mode depth-test
+                       projection textures)
   render-context?
   (viewport render-context-viewport set-render-context-viewport!)
   (framebuffer render-context-framebuffer set-render-context-framebuffer!)
   (blend-mode render-context-blend-mode set-render-context-blend-mode!)
-  (depth-test? render-context-depth-test? set-render-context-depth-test!)
+  (depth-test render-context-depth-test set-render-context-depth-test!)
   (projection render-context-projection set-render-context-projection!)
   (textures render-context-textures))
 
@@ -78,7 +78,7 @@
   (render-context-blend-mode render-context))
 
 (define (current-depth-test)
-  (render-context-depth-test? render-context))
+  (render-context-depth-test render-context))
 
 (define (current-texture i)
   (vector-ref (render-context-textures render-context) i))
@@ -117,7 +117,7 @@
         body ...))
 
 (define-syntax-rule (with-depth-test depth-test body ...)
-  (with (render-context-depth-test? set-render-context-depth-test! depth-test)
+  (with (render-context-depth-test set-render-context-depth-test! depth-test)
         body ...))
 
 (define-syntax-rule (with-texture n texture body ...)
diff --git a/chickadee/render/blend.scm b/chickadee/render/blend.scm
index e5f3ffc..1c0b215 100644
--- a/chickadee/render/blend.scm
+++ b/chickadee/render/blend.scm
@@ -20,8 +20,7 @@
   #:use-module (gl)
   #:use-module (chickadee render gl)
   #:use-module (chickadee render gpu)
-  #:export (apply-blend-mode
-            apply-depth-test))
+  #:export (apply-blend-mode))
 
 (define (apply-blend-mode blend-mode)
   (if blend-mode
@@ -62,8 +61,3 @@
            (gl-blend-func (blending-factor-src one)
                           (blending-factor-dest zero)))))
       (gl-disable (enable-cap blend))))
-
-(define (apply-depth-test depth-test?)
-  (if depth-test?
-      (gl-enable (enable-cap depth-test))
-      (gl-disable (enable-cap depth-test))))
diff --git a/chickadee/render/depth.scm b/chickadee/render/depth.scm
new file mode 100644
index 0000000..2eb4e55
--- /dev/null
+++ b/chickadee/render/depth.scm
@@ -0,0 +1,61 @@
+;;; 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 depth)
+  #: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-depth-test
+            depth-test?
+            depth-test-write?
+            depth-test-function
+            depth-test-near
+            depth-test-far
+            default-depth-test
+            apply-depth-test))
+
+(define-record-type <depth-test>
+  (%make-depth-test write? function near far)
+  depth-test?
+  (write? depth-test-write?)
+  (function depth-test-function)
+  (near depth-test-near)
+  (far depth-test-far))
+
+(define* (make-depth-test #:key (write? #t) (function 'less-than) (near 0.0) (far 1.0))
+  (%make-depth-test write? function near far))
+
+(define default-depth-test (make-depth-test))
+
+(define (apply-depth-test depth-test)
+  (if depth-test
+      (let ((glfunc (match (depth-test-function depth-test)
+                      ('always (depth-function always))
+                      ('never (depth-function never))
+                      ('equal (depth-function equal))
+                      ('not-equal (depth-function notequal))
+                      ('less-than (depth-function less))
+                      ('less-than-or-equal (depth-function lequal))
+                      ('greater-than (depth-function greater))
+                      ('greater-than-or-equal (depth-function gequal)))))
+        (gl-enable (enable-cap depth-test))
+        (gl-depth-func glfunc)
+        (gl-depth-mask (depth-test-write? depth-test))
+        (gl-depth-range (depth-test-near depth-test) (depth-test-far depth-test)))
+      (gl-disable (enable-cap depth-test))))
diff --git a/chickadee/render/gl.scm b/chickadee/render/gl.scm
index 295a7bb..67d8ef1 100644
--- a/chickadee/render/gl.scm
+++ b/chickadee/render/gl.scm
@@ -306,3 +306,13 @@ object.")
 ;;;
 
 (re-export (%glGetString . gl-get-string))
+
+
+;;;
+;;; Depth Buffer
+;;;
+
+(re-export (%glDepthFunc . gl-depth-func)
+           (%glDepthMask . gl-depth-mask)
+           (%glDepthRange . gl-depth-range))
+
diff --git a/chickadee/render/gpu.scm b/chickadee/render/gpu.scm
index 554e263..3974c68 100644
--- a/chickadee/render/gpu.scm
+++ b/chickadee/render/gpu.scm
@@ -127,6 +127,7 @@ from the GPU's memory."
   (let ((textures (make-vector 32))
         ;; Lazily resolve bindings to avoid circular dependencies.
         (blend-module (resolve-interface '(chickadee render blend)))
+        (depth-module (resolve-interface '(chickadee render depth)))
         (buffer-module (resolve-interface '(chickadee render buffer)))
         (framebuffer-module (resolve-interface '(chickadee render framebuffer)))
         (shader-module (resolve-interface '(chickadee render shader)))
@@ -148,8 +149,7 @@ from the GPU's memory."
                glsl-version
                (make-gpu-state (module-ref blend-module 'apply-blend-mode)
                                'replace)
-               (make-gpu-state (module-ref blend-module 'apply-depth-test)
-                               #f)
+               (make-gpu-state (module-ref depth-module 'apply-depth-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)
diff --git a/chickadee/render/model.scm b/chickadee/render/model.scm
index 2e73506..a9133c4 100644
--- a/chickadee/render/model.scm
+++ b/chickadee/render/model.scm
@@ -29,6 +29,7 @@
   #:use-module (chickadee render)
   #:use-module (chickadee render buffer)
   #:use-module (chickadee render color)
+  #:use-module (chickadee render depth)
   #:use-module (chickadee render pbr)
   #:use-module (chickadee render phong)
   #:use-module (chickadee render shader)
@@ -175,7 +176,7 @@
   (%make-model name scenes default-scene render-state))
 
 (define (draw-model model model-matrix view-matrix)
-  (with-depth-test #t
+  (with-depth-test default-depth-test
     (let ((state (model-render-state model)))
      (render-state-reset! state)
      (render-state-view-matrix-mult! state view-matrix)