From b457dfd8b838ad63613c4c19edf51f43af4943a5 Mon Sep 17 00:00:00 2001
From: "glassmancody.info" <glassmancody.info@gmail.com>
Date: Fri, 4 Jun 2021 12:13:52 -0700
Subject: [PATCH] fix water RTTs and minor math error in non-infinite
 projection matrix

---
 components/sceneutil/util.cpp | 31 +++++++++++++++++++++++++++++--
 components/sceneutil/util.hpp | 17 +++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/components/sceneutil/util.cpp b/components/sceneutil/util.cpp
index 2e37260eb7..79fe5d13c5 100644
--- a/components/sceneutil/util.cpp
+++ b/components/sceneutil/util.cpp
@@ -150,6 +150,33 @@ void GlowUpdater::setDuration(float duration)
     mDuration = duration;
 }
 
+AttachMultisampledDepthColorCallback::AttachMultisampledDepthColorCallback(const osg::ref_ptr<osg::Texture2D>& colorTex, const osg::ref_ptr<osg::Texture2D>& depthTex, int samples, int colorSamples)
+{
+    int width = colorTex->getTextureWidth();
+    int height = colorTex->getTextureHeight();
+
+    osg::ref_ptr<osg::RenderBuffer> rbColor = new osg::RenderBuffer(width, height, colorTex->getInternalFormat(), samples, colorSamples);
+    osg::ref_ptr<osg::RenderBuffer> rbDepth = new osg::RenderBuffer(width, height, depthTex->getInternalFormat(), samples, colorSamples);
+
+    mMsaaFbo = new osg::FrameBufferObject;
+    mMsaaFbo->setAttachment(osg::Camera::COLOR_BUFFER0, osg::FrameBufferAttachment(rbColor));
+    mMsaaFbo->setAttachment(osg::Camera::DEPTH_BUFFER, osg::FrameBufferAttachment(rbDepth));
+
+    mFbo = new osg::FrameBufferObject;
+    mFbo->setAttachment(osg::Camera::COLOR_BUFFER0, osg::FrameBufferAttachment(colorTex));
+    mFbo->setAttachment(osg::Camera::DEPTH_BUFFER, osg::FrameBufferAttachment(depthTex));
+}
+
+void AttachMultisampledDepthColorCallback::operator()(osg::Node* node, osg::NodeVisitor* nv)
+{
+    osgUtil::RenderStage* renderStage = nv->asCullVisitor()->getCurrentRenderStage();
+
+    renderStage->setMultisampleResolveFramebufferObject(mFbo);
+    renderStage->setFrameBufferObject(mMsaaFbo);
+
+    traverse(node, nv);
+}
+
 void transformBoundingSphere (const osg::Matrixf& matrix, osg::BoundingSphere& bsphere)
 {
     osg::BoundingSphere::vec_type xdash = bsphere._center;
@@ -308,8 +335,8 @@ osg::Matrix getReversedZProjectionMatrixAsPerspective(double fov, double aspect,
     return osg::Matrix(
         A/aspect,   0,      0,                          0,
         0,          A,      0,                          0,
-        0,          0,      far/(far-near)-1.0,         -1,
-        0,          0,      -(far*near)/(far - near),   0
+        0,          0,      near/(far-near),            -1,
+        0,          0,      (far*near)/(far - near),    0
     );
 }
 
diff --git a/components/sceneutil/util.hpp b/components/sceneutil/util.hpp
index 0164e0c99e..69e66bb8b3 100644
--- a/components/sceneutil/util.hpp
+++ b/components/sceneutil/util.hpp
@@ -8,6 +8,7 @@
 #include <osg/Texture2D>
 #include <osg/Vec4f>
 #include <osg/Depth>
+#include <osg/FrameBufferObject>
 
 #include <components/resource/resourcesystem.hpp>
 
@@ -48,6 +49,22 @@ namespace SceneUtil
         bool mDone;
     };
 
+    // Allows camera to render to a color and floating point depth texture with a multisampled framebuffer.
+    // Must be set on a cameras cull callback.
+    // When the depth texture isn't needed as a sampler, use osg::Camera::attach(osg::Camera::DEPTH_COMPONENT, GL_DEPTH_COMPONENT32F) instead.
+    // If multisampling is not being used on the color buffer attachment, use the osg::Camera::attach() method.
+    class AttachMultisampledDepthColorCallback : public osg::NodeCallback
+    {
+    public:
+        AttachMultisampledDepthColorCallback(const osg::ref_ptr<osg::Texture2D>& colorTex, const osg::ref_ptr<osg::Texture2D>& depthTex, int samples, int colorSamples);
+
+        void operator()(osg::Node* node, osg::NodeVisitor* nv) override;
+
+    private:
+        osg::ref_ptr<osg::FrameBufferObject> mFbo;
+        osg::ref_ptr<osg::FrameBufferObject> mMsaaFbo;
+    };
+
     // Transform a bounding sphere by a matrix
     // based off private code in osg::Transform
     // TODO: patch osg to make public