From 1d84d54509946a084db21dedce9680eb609ffed6 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Fri, 2 Dec 2022 13:17:07 +0900
Subject: [PATCH] [vulkan] Add cvars to control vulkan 3d frame buffer size

Thanks to the 3d frame buffer output being separate from the swap chain,
it's possible to have a different frame buffer size from the window
size, allowing for a smaller buffer and thus my laptop can cope (mostly)
with the vulkan renderer.
---
 include/QF/Vulkan/qf_vid.h                    |  3 +++
 libs/video/renderer/vulkan/vulkan_main.c      |  6 +++++
 .../video/renderer/vulkan/vulkan_vid_common.c | 22 +++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/include/QF/Vulkan/qf_vid.h b/include/QF/Vulkan/qf_vid.h
index ff57d9853..8d0e414a1 100644
--- a/include/QF/Vulkan/qf_vid.h
+++ b/include/QF/Vulkan/qf_vid.h
@@ -98,4 +98,7 @@ void Vulkan_BeginEntityLabel (struct vulkan_ctx_s *ctx, VkCommandBuffer cmd,
 
 struct plitem_s *Vulkan_GetConfig (struct vulkan_ctx_s *ctx, const char *name);
 
+extern int vulkan_frame_width;
+extern int vulkan_frame_height;
+
 #endif // __QF_Vulkan_vid_h
diff --git a/libs/video/renderer/vulkan/vulkan_main.c b/libs/video/renderer/vulkan/vulkan_main.c
index d06a526d5..f3d5084fa 100644
--- a/libs/video/renderer/vulkan/vulkan_main.c
+++ b/libs/video/renderer/vulkan/vulkan_main.c
@@ -181,6 +181,12 @@ Vulkan_Main_CreateRenderPasses (vulkan_ctx_t *ctx)
 		.extent    = ctx->swapchain->extent,
 		.frames    = ctx->swapchain->numImages,
 	};
+	if (vulkan_frame_width > 0) {
+		rp->output.extent.width = vulkan_frame_width;
+	}
+	if (vulkan_frame_height > 0) {
+		rp->output.extent.height = vulkan_frame_height;
+	}
 	QFV_RenderPass_CreateAttachments (rp);
 	QFV_RenderPass_CreateRenderPass (rp);
 	QFV_RenderPass_CreateFramebuffer (rp);
diff --git a/libs/video/renderer/vulkan/vulkan_vid_common.c b/libs/video/renderer/vulkan/vulkan_vid_common.c
index f7df0a5b7..d504c5e3a 100644
--- a/libs/video/renderer/vulkan/vulkan_vid_common.c
+++ b/libs/video/renderer/vulkan/vulkan_vid_common.c
@@ -63,6 +63,26 @@
 #include "vid_vulkan.h"
 #include "vkparse.h"
 
+int vulkan_frame_width;
+static cvar_t vulkan_frame_width_cvar = {
+	.name = "vulkan_frame_width",
+	.description =
+		"Width of 3D view buffer. Set to 0 for automatic sizing.",
+	.default_value = "0",
+	.flags = CVAR_NONE,
+	.value = { .type = &cexpr_int, .value = &vulkan_frame_width },
+};
+
+int vulkan_frame_height;
+static cvar_t vulkan_frame_height_cvar = {
+	.name = "vulkan_frame_height",
+	.description =
+		"Height of 3D view buffer. Set to 0 for automatic sizing.",
+	.default_value = "0",
+	.flags = CVAR_NONE,
+	.value = { .type = &cexpr_int, .value = &vulkan_frame_height },
+};
+
 static const char *instance_extensions[] = {
 	VK_KHR_SURFACE_EXTENSION_NAME,
 	VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME,
@@ -79,6 +99,8 @@ Vulkan_Init_Common (vulkan_ctx_t *ctx)
 {
 	Sys_MaskPrintf (SYS_vulkan, "Vulkan_Init_Common\n");
 
+	Cvar_Register (&vulkan_frame_width_cvar, 0, 0);
+	Cvar_Register (&vulkan_frame_height_cvar, 0, 0);
 	Vulkan_Init_Cvars ();
 	R_Init_Cvars ();
 	Vulkan_Script_Init (ctx);