From 73f00bd8420a9125a8a5f8c5bbfed1a3be80f849 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Garc=C3=ADa=20Li=C3=B1=C3=A1n?=
 <fernandogarcialinan@gmail.com>
Date: Sun, 22 Mar 2020 16:49:18 +0100
Subject: [PATCH] Compositor: Added support for logarithmic depth buffer.

---
 simgear/scene/viewer/Compositor.cxx     | 11 +++++++++++
 simgear/scene/viewer/Compositor.hxx     |  2 ++
 simgear/scene/viewer/CompositorPass.cxx |  5 ++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/simgear/scene/viewer/Compositor.cxx b/simgear/scene/viewer/Compositor.cxx
index e91b1d44..ffaccdba 100644
--- a/simgear/scene/viewer/Compositor.cxx
+++ b/simgear/scene/viewer/Compositor.cxx
@@ -129,6 +129,8 @@ Compositor::Compositor(osg::View *view,
     new osg::Uniform("fg_PrevProjectionMatrixInverse", osg::Matrixf()),
     new osg::Uniform("fg_CameraPositionCart", osg::Vec3f()),
     new osg::Uniform("fg_CameraPositionGeod", osg::Vec3f()),
+    new osg::Uniform("fg_NearFarPlanes", osg::Vec3f()),
+    new osg::Uniform("fg_Fcoef", 0.0f),
     new osg::Uniform("fg_LightDirection", osg::Vec3f())
     }
 {
@@ -165,6 +167,9 @@ Compositor::update(const osg::Matrix &view_matrix,
     SGGeod camera_pos_geod = SGGeod::fromCart(
         SGVec3d(camera_pos.x(), camera_pos.y(), camera_pos.z()));
 
+    double left, right, bottom, top, zNear, zFar;
+    proj_matrix.getFrustum(left, right, bottom, top, zNear, zFar);
+
     osg::Matrixf prev_view_matrix, prev_view_matrix_inv;
     _uniforms[VIEW_MATRIX]->get(prev_view_matrix);
     _uniforms[VIEW_MATRIX_INV]->get(prev_view_matrix_inv);
@@ -203,6 +208,12 @@ Compositor::update(const osg::Matrix &view_matrix,
                               camera_pos_geod.getLatitudeRad(),
                               camera_pos_geod.getElevationM()));
             break;
+        case NEAR_FAR_PLANES:
+            u->set(osg::Vec3f(-zFar, -zFar * zNear, zFar - zNear));
+            break;
+        case FCOEF:
+            u->set(2.0f / log2(float(zFar) + 1.0f));
+            break;
         default:
             // Unknown uniform
             break;
diff --git a/simgear/scene/viewer/Compositor.hxx b/simgear/scene/viewer/Compositor.hxx
index 23855347..f7e538c9 100644
--- a/simgear/scene/viewer/Compositor.hxx
+++ b/simgear/scene/viewer/Compositor.hxx
@@ -57,6 +57,8 @@ public:
         PREV_PROJECTION_MATRIX_INV,
         CAMERA_POSITION_CART,
         CAMERA_POSITION_GEOD,
+        NEAR_FAR_PLANES,
+        FCOEF,
         LIGHT_DIRECTION,
         TOTAL_BUILTIN_UNIFORMS
     };
diff --git a/simgear/scene/viewer/CompositorPass.cxx b/simgear/scene/viewer/CompositorPass.cxx
index aa727305..dd89237f 100644
--- a/simgear/scene/viewer/CompositorPass.cxx
+++ b/simgear/scene/viewer/CompositorPass.cxx
@@ -385,7 +385,6 @@ public:
 
     virtual void operator()(osg::Node *node, osg::NodeVisitor *nv) {
         osg::Camera *camera = static_cast<osg::Camera *>(node);
-        EffectCullVisitor *cv = dynamic_cast<EffectCullVisitor *>(nv);
 
         traverse(node, nv);
 
@@ -720,6 +719,10 @@ public:
             }
         }
 
+        osg::StateSet *ss = camera->getOrCreateStateSet();
+        auto &uniforms = compositor->getUniforms();
+        ss->addUniform(uniforms[Compositor::FCOEF]);
+
         return pass.release();
     }
 };