From 25559243ae09db2f278cff24bb6288c453468149 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Tue, 30 Nov 2021 21:00:33 +0900
Subject: [PATCH] [vulkan] Add function to compute next offset

When allocating memory for multiple objects that have alignment
requirements, it gets tedious keeping track of the offset and the
alignment. This is a simple function for walking the offset respecting
size and alignment requirements, and doubles as a size calculator.
---
 include/QF/Vulkan/buffer.h                   | 4 ++++
 libs/video/renderer/vulkan/buffer.c          | 9 +++++++++
 libs/video/renderer/vulkan/vulkan_lighting.c | 8 +++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/QF/Vulkan/buffer.h b/include/QF/Vulkan/buffer.h
index 712b14a96..f9cbbb0c9 100644
--- a/include/QF/Vulkan/buffer.h
+++ b/include/QF/Vulkan/buffer.h
@@ -45,4 +45,8 @@ VkBufferView QFV_CreateBufferView (struct qfv_device_s *device,
 								   VkBuffer buffer, VkFormat format,
 								   VkDeviceSize offset, VkDeviceSize size);
 
+VkDeviceSize QFV_NextOffset (VkDeviceSize current, VkDeviceSize count,
+							 const VkMemoryRequirements *requirements)
+	__attribute__((pure));
+
 #endif//__QF_Vulkan_buffer_h
diff --git a/libs/video/renderer/vulkan/buffer.c b/libs/video/renderer/vulkan/buffer.c
index eb9da832c..063fe8c73 100644
--- a/libs/video/renderer/vulkan/buffer.c
+++ b/libs/video/renderer/vulkan/buffer.c
@@ -162,3 +162,12 @@ QFV_CreateBufferView (qfv_device_t *device, VkBuffer buffer, VkFormat format,
 	dfunc->vkCreateBufferView (dev, &createInfo, 0, &view);
 	return view;
 }
+
+VkDeviceSize
+QFV_NextOffset (VkDeviceSize current, VkDeviceSize count,
+				const VkMemoryRequirements *requirements)
+{
+	VkDeviceSize align = requirements->alignment - 1;
+	VkDeviceSize size = (requirements->size + align) & ~align;
+	return ((current + align) & ~align) + count * size;
+}
diff --git a/libs/video/renderer/vulkan/vulkan_lighting.c b/libs/video/renderer/vulkan/vulkan_lighting.c
index ce13b7bed..755e7d919 100644
--- a/libs/video/renderer/vulkan/vulkan_lighting.c
+++ b/libs/video/renderer/vulkan/vulkan_lighting.c
@@ -327,8 +327,8 @@ Vulkan_Lighting_Init (vulkan_ctx_t *ctx)
 	dfunc->vkGetBufferMemoryRequirements (device->dev, lbuffers->a[0],
 										  &requirements);
 	lctx->light_memory = QFV_AllocBufferMemory (device, lbuffers->a[0],
-										VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
-										frames * requirements.size, 0);
+								VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
+								QFV_NextOffset (0, frames, &requirements), 0);
 	QFV_duSetObjectName (device, VK_OBJECT_TYPE_DEVICE_MEMORY,
 						 lctx->light_memory, "memory:lighting");
 
@@ -359,6 +359,7 @@ Vulkan_Lighting_Init (vulkan_ctx_t *ctx)
 														lights);
 	__auto_type shadow_set = QFV_AllocateDescriptorSet (device, shadow_pool,
 														shadow);
+	VkDeviceSize light_offset = 0;
 	for (size_t i = 0; i < frames; i++) {
 		__auto_type lframe = &lctx->frames.a[i];
 
@@ -382,7 +383,8 @@ Vulkan_Lighting_Init (vulkan_ctx_t *ctx)
 
 		lframe->light_buffer = lbuffers->a[i];
 		QFV_BindBufferMemory (device, lbuffers->a[i], lctx->light_memory,
-							  i * requirements.size);
+							  light_offset);
+		light_offset = QFV_NextOffset (light_offset, 1, &requirements);
 
 		QFV_duSetObjectName (device, VK_OBJECT_TYPE_COMMAND_BUFFER,
 							 lframe->cmd, "cmd:lighting");