GL: Framebuffer: Add support for empty framebuffer (no attachments)

This allows to reduce the memory footprint of very large framebuffers if
there is no need for any attachment.

2 files changed, 6 insertions, 1 deletions

diff --git a/source/blender/gpu/opengl/gl_framebuffer.cc b/source/blender/gpu/opengl/gl_framebuffer.cc
index bd9fba4250d..1ab22a16df4 100644
--- a/source/blender/gpu/opengl/gl_framebuffer.cc
+++ b/source/blender/gpu/opengl/gl_framebuffer.cc
@@ -207,6 +207,11 @@ void GLFrameBuffer::update_attachments()
     this->size_set(size[0], size[1]);
     srgb_ = (GPU_texture_format(attach.tex) == GPU_SRGB8_A8);
   }
+  else {
+    /* Empty frame-buffer. */
+    glFramebufferParameteri(GL_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_WIDTH, width_);
+    glFramebufferParameteri(GL_FRAMEBUFFER, GL_FRAMEBUFFER_DEFAULT_HEIGHT, height_);
+  }
 
   dirty_attachments_ = false;
 
diff --git a/source/blender/gpu/opengl/gl_framebuffer.hh b/source/blender/gpu/opengl/gl_framebuffer.hh
index 8ee04a584bd..edc05322153 100644
--- a/source/blender/gpu/opengl/gl_framebuffer.hh
+++ b/source/blender/gpu/opengl/gl_framebuffer.hh
@@ -32,7 +32,7 @@ class GLFrameBuffer : public FrameBuffer {
   /** State Manager of the same contexts. */
   GLStateManager *state_manager_ = nullptr;
   /** Copy of the GL state. Contains ONLY color attachments enums for slot binding. */
-  GLenum gl_attachments_[GPU_FB_MAX_COLOR_ATTACHMENT];
+  GLenum gl_attachments_[GPU_FB_MAX_COLOR_ATTACHMENT] = {0};
   /** Internal frame-buffers are immutable. */
   bool immutable_;
   /** True is the frame-buffer has its first color target using the GPU_SRGB8_A8 format. */