Skip to content

VKFrameBuffer

Viewport Orientation

Blender uses top left as the origin of the framebuffer. Vulkan uses the bottom left. When drawing to the on-screen framebuffer each draw command is flipped. This is done by providing a negative viewport.

classDiagram

    class VKFrameBuffer {
        -bool flip_viewport_
        +VkViewport vk_viewport_get() const
    }

Framebuffers have an attribute to indicate that all draw/blit operations to this frame buffer should be flipped.

Draw commands are automatically flipped as the VkViewport created for the graphics pipeline is flipped. This is done in VKFrameBuffer::vk_viewport_get().

When transferring data from framebuffer A to framebuffer B the flipping only needs to happen when flip_viewport_ differs. When different the dstOffsets of the VkBlitCmdImage is flipped. This is done in VKFrameBuffer::blit_to.

References

  • source/blender/gpu/vulkan/vk_framebuffer.hh
  • source/blender/gpu.vulkan/vk_framebuffer.cc
Last update: 2023-06-12
Created: 2023-06-12