From 7c41ae5b61fbe99678e1bf1c7e3a33c59306d84f Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Fri, 10 Apr 2026 22:18:35 -0500
Subject: [PATCH] clamp lower bound of mipmap width/height

Prior to this commit, width/height values could be right-shifted to
zero (when loading non-square textures).
---
 source/main.cpp        | 7 ++++++-
 tutorial/docs/index.md | 6 +++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/source/main.cpp b/source/main.cpp
index d33f52d..bdce8ba 100644
--- a/source/main.cpp
+++ b/source/main.cpp
@@ -12,6 +12,7 @@
 #include <string>
 #include <iostream>
 #include <fstream>
+#include <algorithm>
 #define VMA_IMPLEMENTATION
 #include <vma/vk_mem_alloc.h>
 #define GLM_FORCE_RADIANS
@@ -344,7 +345,11 @@ int main(int argc, char* argv[])
 			copyRegions.push_back({
 				.bufferOffset = mipOffset,
 				.imageSubresource{.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT, .mipLevel = (uint32_t)j, .layerCount = 1},
-				.imageExtent{.width = ktxTexture->baseWidth >> j, .height = ktxTexture->baseHeight >> j, .depth = 1 },
+				.imageExtent{
+					.width = std::max(1, ktxTexture->baseWidth >> j),
+					.height = std::max(1, ktxTexture->baseHeight >> j),
+					.depth = 1
+				},
 			});
 		}
 		vkCmdCopyBufferToImage(cbOneTime, imgSrcBuffer, textures[i].image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, static_cast<uint32_t>(copyRegions.size()), copyRegions.data());
diff --git a/tutorial/docs/index.md b/tutorial/docs/index.md
index 1879bf2..0c3b80a 100644
--- a/tutorial/docs/index.md
+++ b/tutorial/docs/index.md
@@ -868,7 +868,11 @@ for (auto j = 0; j < ktxTexture->numLevels; j++) {
 	copyRegions.push_back({
 		.bufferOffset = mipOffset,
 		.imageSubresource{.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT, .mipLevel = (uint32_t)j, .layerCount = 1},
-		.imageExtent{.width = ktxTexture->baseWidth >> j, .height = ktxTexture->baseHeight >> j, .depth = 1 },
+		.imageExtent{
+			.width = std::max(1, ktxTexture->baseWidth >> j),
+			.height = std::max(1, ktxTexture->baseHeight >> j),
+			.depth = 1
+		},
 	});
 }
 vkCmdCopyBufferToImage(cbOneTime, imgSrcBuffer, textures[i].image, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, static_cast<uint32_t>(copyRegions.size()), copyRegions.data());