godot/modules/openxr/extensions/openxr_composition_layer_extension.cpp

/**************************************************************************/
/*  openxr_composition_layer_extension.cpp                                */
/**************************************************************************/
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/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#include "openxr_composition_layer_extension.h"

#include "servers/rendering/rendering_server_globals.h"

////////////////////////////////////////////////////////////////////////////
// OpenXRCompositionLayerExtension

OpenXRCompositionLayerExtension *OpenXRCompositionLayerExtension::singleton = nullptr;

OpenXRCompositionLayerExtension *OpenXRCompositionLayerExtension::get_singleton() {
	return singleton;
}

OpenXRCompositionLayerExtension::OpenXRCompositionLayerExtension() {
	singleton = this;
}

OpenXRCompositionLayerExtension::~OpenXRCompositionLayerExtension() {
	singleton = nullptr;
}

HashMap<String, bool *> OpenXRCompositionLayerExtension::get_requested_extensions() {
	HashMap<String, bool *> request_extensions;

	request_extensions[XR_KHR_COMPOSITION_LAYER_CYLINDER_EXTENSION_NAME] = &cylinder_ext_available;
	request_extensions[XR_KHR_COMPOSITION_LAYER_EQUIRECT2_EXTENSION_NAME] = &equirect_ext_available;

	return request_extensions;
}

void OpenXRCompositionLayerExtension::on_session_created(const XrSession p_instance) {
	OpenXRAPI::get_singleton()->register_composition_layer_provider(this);
}

void OpenXRCompositionLayerExtension::on_session_destroyed() {
	OpenXRAPI::get_singleton()->unregister_composition_layer_provider(this);
}

void OpenXRCompositionLayerExtension::on_pre_render() {
	for (OpenXRViewportCompositionLayerProvider *composition_layer : composition_layers) {
		composition_layer->on_pre_render();
	}
}

int OpenXRCompositionLayerExtension::get_composition_layer_count() {
	return composition_layers.size();
}

XrCompositionLayerBaseHeader *OpenXRCompositionLayerExtension::get_composition_layer(int p_index) {
	ERR_FAIL_INDEX_V(p_index, composition_layers.size(), nullptr);
	return composition_layers[p_index]->get_composition_layer();
}

int OpenXRCompositionLayerExtension::get_composition_layer_order(int p_index) {
	ERR_FAIL_INDEX_V(p_index, composition_layers.size(), 1);
	return composition_layers[p_index]->get_sort_order();
}

void OpenXRCompositionLayerExtension::register_composition_layer_provider(OpenXRViewportCompositionLayerProvider *p_composition_layer) {
	composition_layers.push_back(p_composition_layer);
}

void OpenXRCompositionLayerExtension::unregister_composition_layer_provider(OpenXRViewportCompositionLayerProvider *p_composition_layer) {
	composition_layers.erase(p_composition_layer);
}

bool OpenXRCompositionLayerExtension::is_available(XrStructureType p_which) {
	switch (p_which) {
		case XR_TYPE_COMPOSITION_LAYER_QUAD: {
			// Doesn't require an extension.
			return true;
		} break;
		case XR_TYPE_COMPOSITION_LAYER_CYLINDER_KHR: {
			return cylinder_ext_available;
		} break;
		case XR_TYPE_COMPOSITION_LAYER_EQUIRECT2_KHR: {
			return equirect_ext_available;
		} break;
		default: {
			ERR_PRINT(vformat("Unsupported composition layer type: %s", p_which));
			return false;
		}
	}
}

////////////////////////////////////////////////////////////////////////////
// OpenXRViewportCompositionLayerProvider

OpenXRViewportCompositionLayerProvider::OpenXRViewportCompositionLayerProvider(XrCompositionLayerBaseHeader *p_composition_layer) {
	composition_layer = p_composition_layer;
	openxr_api = OpenXRAPI::get_singleton();
	composition_layer_extension = OpenXRCompositionLayerExtension::get_singleton();
}

OpenXRViewportCompositionLayerProvider::~OpenXRViewportCompositionLayerProvider() {
	// This will reset the viewport and free the swapchain too.
	set_viewport(RID(), Size2i());
}

void OpenXRViewportCompositionLayerProvider::set_alpha_blend(bool p_alpha_blend) {
	if (alpha_blend != p_alpha_blend) {
		alpha_blend = p_alpha_blend;
		if (alpha_blend) {
			composition_layer->layerFlags |= XR_COMPOSITION_LAYER_BLEND_TEXTURE_SOURCE_ALPHA_BIT;
		} else {
			composition_layer->layerFlags &= ~XR_COMPOSITION_LAYER_BLEND_TEXTURE_SOURCE_ALPHA_BIT;
		}
	}
}

void OpenXRViewportCompositionLayerProvider::set_viewport(RID p_viewport, Size2i p_size) {
	RenderingServer *rs = RenderingServer::get_singleton();
	ERR_FAIL_NULL(rs);

	if (viewport != p_viewport) {
		if (viewport.is_valid()) {
			RID rt = rs->viewport_get_render_target(viewport);
			RSG::texture_storage->render_target_set_override(rt, RID(), RID(), RID());
		}

		viewport = p_viewport;

		if (viewport.is_valid()) {
			viewport_size = p_size;
		} else {
			free_swapchain();
			viewport_size = Size2i();
		}
	}
}

void OpenXRViewportCompositionLayerProvider::on_pre_render() {
	RenderingServer *rs = RenderingServer::get_singleton();
	ERR_FAIL_NULL(rs);

	if (viewport.is_valid() && openxr_api && openxr_api->is_running()) {
		RS::ViewportUpdateMode update_mode = rs->viewport_get_update_mode(viewport);
		if (update_mode == RS::VIEWPORT_UPDATE_ONCE || update_mode == RS::VIEWPORT_UPDATE_ALWAYS) {
			// Update our XR swapchain
			if (update_and_acquire_swapchain(update_mode == RS::VIEWPORT_UPDATE_ONCE)) {
				// Render to our XR swapchain image.
				RID rt = rs->viewport_get_render_target(viewport);
				RSG::texture_storage->render_target_set_override(rt, get_current_swapchain_texture(), RID(), RID());
			}
		}
	}
}

XrCompositionLayerBaseHeader *OpenXRViewportCompositionLayerProvider::get_composition_layer() {
	if (openxr_api == nullptr || composition_layer_extension == nullptr) {
		// OpenXR not initialised or we're in the editor?
		return nullptr;
	}

	if (!composition_layer_extension->is_available(composition_layer->type)) {
		// Selected type is not supported, ignore our layer.
		return nullptr;
	}

	if (swapchain_info.swapchain == XR_NULL_HANDLE) {
		// Don't have a swapchain to display? Ignore our layer.
		return nullptr;
	}

	if (swapchain_info.image_acquired) {
		openxr_api->release_image(swapchain_info);
	}

	// Update the layer struct for the swapchain.
	switch (composition_layer->type) {
		case XR_TYPE_COMPOSITION_LAYER_QUAD: {
			XrCompositionLayerQuad *quad_layer = (XrCompositionLayerQuad *)composition_layer;
			quad_layer->subImage.swapchain = swapchain_info.swapchain;
			quad_layer->subImage.imageArrayIndex = 0;
			quad_layer->subImage.imageRect.offset.x = 0;
			quad_layer->subImage.imageRect.offset.y = 0;
			quad_layer->subImage.imageRect.extent.width = swapchain_size.width;
			quad_layer->subImage.imageRect.extent.height = swapchain_size.height;
		} break;

		case XR_TYPE_COMPOSITION_LAYER_CYLINDER_KHR: {
			XrCompositionLayerCylinderKHR *cylinder_layer = (XrCompositionLayerCylinderKHR *)composition_layer;
			cylinder_layer->subImage.swapchain = swapchain_info.swapchain;
			cylinder_layer->subImage.imageArrayIndex = 0;
			cylinder_layer->subImage.imageRect.offset.x = 0;
			cylinder_layer->subImage.imageRect.offset.y = 0;
			cylinder_layer->subImage.imageRect.extent.width = swapchain_size.width;
			cylinder_layer->subImage.imageRect.extent.height = swapchain_size.height;
		} break;

		case XR_TYPE_COMPOSITION_LAYER_EQUIRECT2_KHR: {
			XrCompositionLayerEquirect2KHR *equirect_layer = (XrCompositionLayerEquirect2KHR *)composition_layer;
			equirect_layer->subImage.swapchain = swapchain_info.swapchain;
			equirect_layer->subImage.imageArrayIndex = 0;
			equirect_layer->subImage.imageRect.offset.x = 0;
			equirect_layer->subImage.imageRect.offset.y = 0;
			equirect_layer->subImage.imageRect.extent.width = swapchain_size.width;
			equirect_layer->subImage.imageRect.extent.height = swapchain_size.height;
		} break;

		default: {
			return nullptr;
		} break;
	}

	return composition_layer;
}

bool OpenXRViewportCompositionLayerProvider::update_and_acquire_swapchain(bool p_static_image) {
	if (openxr_api == nullptr || composition_layer_extension == nullptr) {
		// OpenXR not initialised or we're in the editor?
		return false;
	}
	if (!composition_layer_extension->is_available(composition_layer->type)) {
		// Selected type is not supported?
		return false;
	}

	// See if our current swapchain is outdated.
	if (swapchain_info.swapchain != XR_NULL_HANDLE) {
		// If this swap chain, or the previous one, were static, then we can't reuse it.
		if (swapchain_size == viewport_size && !p_static_image && !static_image) {
			// We're all good! Just acquire it.
			return openxr_api->acquire_image(swapchain_info);
		}

		openxr_api->free_swapchain(swapchain_info);
	}

	// Create our new swap chain
	int64_t swapchain_format = openxr_api->get_color_swapchain_format();
	const uint32_t sample_count = 3;
	const uint32_t array_size = 1;
	XrSwapchainCreateFlags create_flags = 0;
	if (p_static_image) {
		create_flags |= XR_SWAPCHAIN_CREATE_STATIC_IMAGE_BIT;
	}
	if (!openxr_api->create_swapchain(create_flags, XR_SWAPCHAIN_USAGE_SAMPLED_BIT | XR_SWAPCHAIN_USAGE_COLOR_ATTACHMENT_BIT | XR_SWAPCHAIN_USAGE_MUTABLE_FORMAT_BIT, swapchain_format, viewport_size.width, viewport_size.height, sample_count, array_size, swapchain_info.swapchain, &swapchain_info.swapchain_graphics_data)) {
		swapchain_size = Size2i();
		return false;
	}

	// Acquire our image so we can start rendering into it
	bool ret = openxr_api->acquire_image(swapchain_info);

	swapchain_size = viewport_size;
	static_image = p_static_image;
	return ret;
}

void OpenXRViewportCompositionLayerProvider::free_swapchain() {
	if (swapchain_info.swapchain != XR_NULL_HANDLE) {
		openxr_api->free_swapchain(swapchain_info);
	}

	swapchain_size = Size2i();
	static_image = false;
}

RID OpenXRViewportCompositionLayerProvider::get_current_swapchain_texture() {
	if (openxr_api == nullptr) {
		return RID();
	}

	return openxr_api->get_image(swapchain_info);
}