This extension provides an API to create a swapchain directly on a device’s display without any underlying window system.
Extending VkStructureType
:
VK_STRUCTURE_TYPE_DISPLAY_PRESENT_INFO_KHR
Extending VkResult
:
VK_ERROR_INCOMPATIBLE_DISPLAY_KHR
1) Should swapchains sharing images each hold a reference to the images, or should it be up to the application to destroy the swapchains and images in an order that avoids the need for reference counting?
PROPOSED RESOLUTION: Take a reference. The lifetime of presentable images is already complex enough.
2) Should the srcRect/dstRect parameters be specified as part of the present command, or at swapchain creation time?
PROPOSED RESOLUTION: As part of the presentation command. This allows moving and scaling the image on the screen without the need to respecify the mode or create a new swapchain presentable images.
3) Should srcRect/dstRect be specified as rects, or separate offset/extent values?
PROPOSED RESOLUTION: As rects. Specifying them separately might make it easier for hardware to expose support for one but not the other, but in such cases applications must just take care to obey the reported capabilities and not use non-zero offsets or extents that require scaling, as appropriate.
4) How can applications create multiple swapchains that use the same images?
RESOLUTION: By calling vkCreateSharedSwapchainsKHR().
An earlier resolution used vkCreateSwapchainKHR(), chaining multiple VkSwapchainCreateInfoKHR structures through pNext. In order to allow each swapchain to also allow other extension structs, a level of indirection was used: VkSwapchainCreateInfoKHR::pNext pointed to a different structure, which had both an sType/pNext for additional extensions, and also had a pointer to the next VkSwapchainCreateInfoKHR structure. The number of swapchains to be created could only be found by walking this linked list of alternating structures, and the pSwapchains out parameter was reinterpreted to be an array of VkSwapchainKHR handles.
Another option considered was a method to specify a "shared" swapchain when creating a new swapchain, such that groups of swapchains using the same images could be built up one at a time. This was deemed unusable because drivers need to know all of the displays an image will be used on when determining which internal formats and layouts to use for that image.
Example 1
Create a swapchain on a display mode and plane
// See VK_KHR_display for an example of how to pick a display, // display mode, plane, and how to create a VkSurfaceKHR for // that plane. extern VkPhysicalDevice physDevice; extern VkDisplayModePropertiesKHR myModeProps; extern VkSurfaceKHR mySurface; extern VkDevice device; uint32_t queueCount, i; uint32_t presentQueueFamilyIndex = UINT32_MAX; VkBool32 supportsPresent; // Find a queue family that supports presenting to this surface uint32_t familyCount; vkGetPhysicalDeviceQueueFamilyProperties(physDevice, &familyCount, NULL); for (i = 0; i < familyCount; ++i) { vkGetPhysicalDeviceSurfaceSupportKHR(physDevice, i, mySurface, &supportsPresent); if (supportsPresent) { // Found a queue family that supports present. See // VK_KHR_surface for an example of how to find a queue that // supports both presentation and graphics presentQueueFamilyIndex = i; break; } } // Figure out which formats and present modes this surface supports. uint32_t formatCount; vkGetPhysicalDeviceSurfaceFormatsKHR(physDevice, mySurface, &formatCount, NULL); VkSurfaceFormatKHR* formats = (VkSurfaceFormatKHR*)malloc(sizeof(VkSurfaceFormatKHR) * formatCount); vkGetPhysicalDeviceSurfaceFormatsKHR(physDevice, mySurface, &formatCount, formats); const VkSwapchainCreateInfoKHR createInfo = { VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR, // sType NULL, // pNext 0, // flags mySurface, // surface 3, // minImageCount formats[0].format, // imageFormat formats[0].colorSpace, // imageColorSpace myModeProps.parameters.visibleRegion, // imageExtent 1, // imageArrayLayers VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT, // imageUsage VK_SHARING_MODE_EXCLUSIVE, // imageSharingMode 0, // queueFamilyIndexCount NULL, // pQueueFamilyIndices VK_SURFACE_TRANSFORM_IDENTITY_BIT_KHR, // preTransform VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR, // compositeAlpha VK_PRESENT_MODE_FIFO_KHR, // presentMode VK_TRUE, // clipped VK_NULL_HANDLE // oldSwapchain }; VkSwapchainKHR swapchain; // This is equivalent to vkCreateSwapchainKHR. vkCreateSharedSwapchainsKHR(device, 1, &createInfo, NULL, &swapchain);
Revision 1, 2015-07-29 (James Jones)
Revision 2, 2015-08-21 (Ian Elliott)
Revision 3, 2015-09-01 (James Jones)
Revision 4, 2015-09-08 (James Jones)
Revision 5, 2015-09-10 (Alon Or-bach)
Revision 6, 2015-10-02 (James Jones)
Revision 7, 2015-10-26 (Ian Elliott)
Revision 8, 2015-11-03 (Daniel Rakos)
Revision 9, 2015-11-10 (Jesse Hall)