From 2c99a81b2cb7428c2d03eca98617aa34279ea166 Mon Sep 17 00:00:00 2001
From: Cory Quammen <cory.quammen@kitware.com>
Date: Fri, 7 Feb 2025 17:02:52 -0500
Subject: [PATCH] vtkValuePass: save and restores GL state to fix rendering
issues
When initializing the FBOs, blending, scissor testing, and depth
testing are disabled for the first render, which leads to junk results
on the first render. Fix by saving and restoring that OpenGL state.
---
Rendering/OpenGL2/vtkValuePass.cxx | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/Rendering/OpenGL2/vtkValuePass.cxx b/Rendering/OpenGL2/vtkValuePass.cxx
index 3af34b82355..9e596080680 100644
--- a/Rendering/OpenGL2/vtkValuePass.cxx
+++ b/Rendering/OpenGL2/vtkValuePass.cxx
@@ -621,6 +621,13 @@ bool vtkValuePass::InitializeFBO(vtkRenderer* ren)
this->ImplFloat->ValueFBO = vtkOpenGLFramebufferObject::New();
this->ImplFloat->ValueFBO->SetContext(renWin);
renWin->GetState()->PushFramebufferBindings();
+
+ // vtkOpenGLFramebufferObject::InitializeViewport disables blending, scissor test and
+ // depth test. Save and restore them in scoped variables.
+ vtkOpenGLState* glstate = renWin->GetState();
+ vtkOpenGLState::ScopedglEnableDisable blendState(glstate, GL_BLEND);
+ vtkOpenGLState::ScopedglEnableDisable depthTestState(glstate, GL_DEPTH_TEST);
+ vtkOpenGLState::ScopedglEnableDisable scissorTestState(glstate, GL_SCISSOR_TEST);
this->ImplFloat->ValueFBO->Bind();
this->ImplFloat->ValueFBO->InitializeViewport(size[0], size[1]);
/* GL_COLOR_ATTACHMENT0 */
@@ -635,7 +642,7 @@ bool vtkValuePass::InitializeFBO(vtkRenderer* ren)
return false;
}
- renWin->GetState()->PopFramebufferBindings();
+ glstate->PopFramebufferBindings();
this->ImplFloat->FBOAllocated = true;
return true;
--
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