diff --git a/include/QF/Vulkan/qf_output.h b/include/QF/Vulkan/qf_output.h
index 7ddfaddbb..eecd2c6b2 100644
--- a/include/QF/Vulkan/qf_output.h
+++ b/include/QF/Vulkan/qf_output.h
@@ -33,6 +33,7 @@
 #include "QF/darray.h"
 #include "QF/Vulkan/qf_vid.h"
 #include "QF/Vulkan/command.h"
+#include "QF/Vulkan/render.h"
 
 typedef struct outputframe_s {
 	VkImageView input;
@@ -47,6 +48,7 @@ typedef struct outputctx_s {
 	VkSampler    sampler;
 	VkImageView  input;
 	VkFramebuffer *framebuffers;	// one per swapchain image
+	qfv_attachmentinfo_t swapchain_info;
 } outputctx_t;
 
 struct vulkan_ctx_s;
diff --git a/include/QF/Vulkan/render.h b/include/QF/Vulkan/render.h
index f941da97c..120224320 100644
--- a/include/QF/Vulkan/render.h
+++ b/include/QF/Vulkan/render.h
@@ -421,10 +421,13 @@ typedef struct qfv_renderframe_s {
 
 typedef struct qfv_renderframeset_s
 	DARRAY_TYPE (qfv_renderframe_t) qfv_renderframeset_t;
+typedef struct qfv_attachmentinfoset_s
+	DARRAY_TYPE (qfv_attachmentinfo_t *) qfv_attachmentinfoset_t;
 
 typedef struct qfv_renderctx_s {
 	struct hashctx_s *hashctx;
 	exprtab_t   task_functions;
+	qfv_attachmentinfoset_t external_attachments;
 	qfv_jobinfo_t *jobinfo;
 	qfv_samplerinfo_t *samplerinfo;
 	qfv_job_t  *job;
@@ -451,6 +454,9 @@ void QFV_BuildRender (struct vulkan_ctx_s *ctx);
 void QFV_Render_Init (struct vulkan_ctx_s *ctx);
 void QFV_Render_Shutdown (struct vulkan_ctx_s *ctx);
 void QFV_Render_AddTasks (struct vulkan_ctx_s *ctx, exprsym_t *task_sys);
+void QFV_Render_AddAttachments (struct vulkan_ctx_s *ctx,
+								uint32_t num_attachments,
+		                        qfv_attachmentinfo_t **attachments);
 
 void QFV_DestroyFramebuffer (struct vulkan_ctx_s *ctx, qfv_renderpass_t *rp);
 void QFV_CreateFramebuffer (struct vulkan_ctx_s *ctx, qfv_renderpass_t *rp,
diff --git a/libs/video/renderer/vulkan/render.c b/libs/video/renderer/vulkan/render.c
index e35b38e60..de2232898 100644
--- a/libs/video/renderer/vulkan/render.c
+++ b/libs/video/renderer/vulkan/render.c
@@ -478,6 +478,9 @@ QFV_Render_Init (vulkan_ctx_t *ctx)
 	cexpr_init_symtab (&rctx->task_functions, &ectx);
 	rctx->task_functions.symbols = 0;
 
+	rctx->external_attachments =
+		(qfv_attachmentinfoset_t) DARRAY_STATIC_INIT (4);
+
 	QFV_Render_AddTasks (ctx, render_task_syms);
 
 	auto device = ctx->device;
@@ -560,6 +563,7 @@ QFV_Render_Shutdown (vulkan_ctx_t *ctx)
 	if (rctx->task_functions.tab) {
 		Hash_DelTable (rctx->task_functions.tab);
 	}
+	DARRAY_CLEAR (&rctx->external_attachments);
 	if (rctx->samplerinfo) {
 		auto si = rctx->samplerinfo;
 		for (uint32_t i = 0; i < si->num_samplers; i++) {
@@ -593,6 +597,18 @@ QFV_Render_AddTasks (vulkan_ctx_t *ctx, exprsym_t *task_syms)
 	}
 }
 
+void
+QFV_Render_AddAttachments (vulkan_ctx_t *ctx, uint32_t num_attachments,
+						   qfv_attachmentinfo_t **attachments)
+{
+	auto rctx = ctx->render_context;
+	size_t base = rctx->external_attachments.size;
+	DARRAY_RESIZE (&rctx->external_attachments, base + num_attachments);
+	for (size_t i = 0; i < num_attachments; i++) {
+		rctx->external_attachments.a[base + i] = attachments[i];
+	}
+}
+
 qfv_step_t *
 QFV_FindStep (const char *name, qfv_job_t *job)
 {
diff --git a/libs/video/renderer/vulkan/render_load.c b/libs/video/renderer/vulkan/render_load.c
index 2adf7b6b3..b64cd6314 100644
--- a/libs/video/renderer/vulkan/render_load.c
+++ b/libs/video/renderer/vulkan/render_load.c
@@ -699,22 +699,33 @@ init_spCreate (uint32_t index, qfv_subpassinfo_t *sub, objstate_t *s)
 static void
 init_atCreate (uint32_t index, qfv_attachmentinfo_t *attachments, objstate_t *s)
 {
-	__auto_type ati = &attachments[index];
-	__auto_type atc = &s->ptr.attach[s->inds.num_attachments];
-	__auto_type cvc = &s->ptr.clear[s->inds.num_attachments];
+	auto rctx = s->ctx->render_context;
+	auto ati = &attachments[index];
+	auto atc = &s->ptr.attach[s->inds.num_attachments];
+	auto cvc = &s->ptr.clear[s->inds.num_attachments];
 
 	if (ati->external) {
-		if (!strcmp (ati->external, "$swapchain")) {
-			*atc = (VkAttachmentDescription) {
-				.format = s->ctx->swapchain->format,
-				.samples = 1,
-				.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR,
-				.storeOp = VK_ATTACHMENT_STORE_OP_STORE,
-				.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
-				.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
-				.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
-				.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
-			};
+		bool found = false;
+		for (size_t i = 0; i < rctx->external_attachments.size; i++) {
+			auto ext = rctx->external_attachments.a[i];
+			if (!strcmp (ati->external, ext->name)) {
+				found = true;
+				*atc = (VkAttachmentDescription) {
+					.flags = ext->flags,
+					.format = ext->format,
+					.samples = ext->samples,
+					.loadOp = ext->loadOp,
+					.storeOp = ext->storeOp,
+					.stencilLoadOp = ext->stencilLoadOp,
+					.stencilStoreOp = ext->stencilStoreOp,
+					.initialLayout = ext->initialLayout,
+					.finalLayout = ext->finalLayout,
+				};
+			}
+		}
+		if (!found) {
+			Sys_Error ("%d:%s: invalid external attachment: %s",
+					   ati->line, ati->name, ati->external);
 		}
 	} else {
 		*atc = (VkAttachmentDescription) {
diff --git a/libs/video/renderer/vulkan/vulkan_output.c b/libs/video/renderer/vulkan/vulkan_output.c
index 668100944..bd6873d39 100644
--- a/libs/video/renderer/vulkan/vulkan_output.c
+++ b/libs/video/renderer/vulkan/vulkan_output.c
@@ -316,7 +316,23 @@ Vulkan_Output_Init (vulkan_ctx_t *ctx)
 	outputctx_t *octx = calloc (1, sizeof (outputctx_t));
 	ctx->output_context = octx;
 
+	octx->swapchain_info = (qfv_attachmentinfo_t) {
+		.name = "$swapchain",
+		.format = ctx->swapchain->format,
+		.samples = 1,
+		.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR,
+		.storeOp = VK_ATTACHMENT_STORE_OP_STORE,
+		.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE,
+		.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE,
+		.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED,
+		.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR,
+	};
+
 	QFV_Render_AddTasks (ctx, output_task_syms);
+	qfv_attachmentinfo_t *attachments[] = {
+		&octx->swapchain_info,
+	};
+	QFV_Render_AddAttachments (ctx, 1, attachments);
 }
 
 void