Careful with mipmaps on old OpenGL ES. Lost this check in the refactor, made it clearer than before at least.

Fixes Burnout rendering issue mentioned in #15818

GPU/Common/TextureCacheCommon.cpp

@@ -2307,6 +2307,12 @@ bool TextureCacheCommon::PrepareBuildTexture(BuildTexturePlan &plan, TexCacheEnt
 		plan.levelsToLoad = 1;
 	}
 
+	if (plan.isVideo || plan.depth != 1) {
+		plan.maxPossibleLevels = 1;
+	} else {
+		plan.maxPossibleLevels = log2i(std::min(plan.w * plan.scaleFactor, plan.h * plan.scaleFactor)) + 1;
+	}
+
 	if (plan.levelsToCreate == 1) {
 		entry->status |= TexCacheEntry::STATUS_NO_MIPS;
 	} else {

GPU/Common/TextureCacheCommon.h

@@ -255,6 +255,9 @@ struct BuildTexturePlan {
 	// the missing levels, or limit itself to levelsToLoad levels.
 	int levelsToCreate;
 
+	// The maximum number of mips levels we can create for this texture.
+	int maxPossibleLevels;
+
 	// Load the 0-mip from this PSP texture level instead of 0.
 	// If non-zero, we are only loading one level.
 	int baseLevelSrc;

GPU/GLES/TextureCacheGLES.cpp

@@ -282,8 +282,14 @@ void TextureCacheGLES::BuildTexture(TexCacheEntry *const entry) {
 	} 
 
 	if (!gstate_c.Supports(GPU_SUPPORTS_TEXTURE_LOD_CONTROL)) {
-		// Force no additional mipmaps.
-		plan.levelsToCreate = plan.levelsToLoad;
+		// If the mip chain is not full..
+		if (plan.levelsToCreate != plan.maxPossibleLevels) {
+			// We need to avoid creating mips at all, or generate them all - can't be incomplete
+			// on this hardware (strict OpenGL rules).
+			plan.levelsToCreate = 1;
+			plan.levelsToLoad = 1;
+			entry->status |= TexCacheEntry::STATUS_NO_MIPS;
+		}
 	}
 
 	if (plan.depth == 1) {

GPU/Vulkan/TextureCacheVulkan.cpp

@@ -438,13 +438,6 @@ void TextureCacheVulkan::BuildTexture(TexCacheEntry *const entry) {
 		return;
 	}
 
-	int maxPossibleMipLevels;
-	if (plan.isVideo || plan.depth != 1) {
-		maxPossibleMipLevels = 1;
-	} else {
-		maxPossibleMipLevels = log2i(std::min(plan.w * plan.scaleFactor, plan.h * plan.scaleFactor)) + 1;
-	}
-
 	VkFormat dstFmt = GetDestFormat(GETextureFormat(entry->format), gstate.getClutPaletteFormat());
 
 	if (plan.scaleFactor > 1) {
@@ -456,11 +449,11 @@ void TextureCacheVulkan::BuildTexture(TexCacheEntry *const entry) {
 	// and similar, which don't really need it.
 	if (g_Config.iTexFiltering == TEX_FILTER_AUTO_MAX_QUALITY && plan.w <= 256 && plan.h <= 256) {
 		// Boost the number of mipmaps.
-		if (maxPossibleMipLevels > plan.levelsToCreate) {
+		if (plan.maxPossibleLevels > plan.levelsToCreate) {
 			// We have to generate mips with a shader. This requires decoding to R8G8B8A8_UNORM format to avoid extra complications.
 			dstFmt = VULKAN_8888_FORMAT;
 		}
-		plan.levelsToCreate = maxPossibleMipLevels;
+		plan.levelsToCreate = plan.maxPossibleLevels;
 	}
 
 	// Any texture scaling is gonna move away from the original 16-bit format, if any.