vulkan: fix washed-out and blurry 2D UI rendering (minimap, bigmap)

Resources/Shaders/Vulkan/BasicImage.frag

@@ -27,10 +27,25 @@ layout(location = 1) in vec2 texCoord;
 
 layout(location = 0) out vec4 fragColor;
 
+// The swapchain attachment is VK_FORMAT_B8G8R8A8_SRGB: the hardware
+// sRGB-ENCODES whatever this shader writes. But 2D UI textures are
+// uploaded as UNORM (raw sRGB bytes sampled verbatim) and the GL
+// renderer writes those bytes straight to a non-sRGB framebuffer.
+// Without correction the value gets sRGB-encoded a second time ->
+// washed-out minimap/UI. Fix: do all math in sRGB space exactly like
+// GL, then DECODE to linear so the attachment's encode restores the
+// original bytes.
+vec3 srgbToLinear(vec3 c) {
+	bvec3 lo = lessThanEqual(c, vec3(0.04045));
+	vec3 linLo = c / 12.92;
+	vec3 linHi = pow((c + 0.055) / 1.055, vec3(2.4));
+	return mix(linHi, linLo, vec3(lo));
+}
+
 void main() {
 	vec2 flippedTexCoord = vec2(texCoord.x, 1.0 - texCoord.y);
 	vec4 col = texture(mainTexture, flippedTexCoord);
 	col.xyz *= col.w;
 	col *= color;
-	fragColor = col;
+	fragColor = vec4(srgbToLinear(col.xyz), col.w);
 }

Sources/Draw/Vulkan/VulkanFlatMapRenderer.cpp

@@ -20,6 +20,8 @@
 
 #include "VulkanFlatMapRenderer.h"
 #include "VulkanRenderer.h"
+#include "VulkanImage.h"
+#include "VulkanImageWrapper.h"
 #include <Gui/SDLVulkanDevice.h>
 #include <Client/GameMap.h>
 #include <Client/IImage.h>
@@ -39,6 +41,13 @@ namespace spades {
 
 			Handle<Bitmap> bmp(GenerateBitmap(0, 0, m.Width(), m.Height()), false);
 			image = renderer.CreateImage(*bmp);
+
+			auto* wrapper = dynamic_cast<VulkanImageWrapper*>(image.GetPointerOrNull());
+			if (wrapper && wrapper->GetVulkanImage()) {
+				wrapper->GetVulkanImage()->CreateSampler(
+					VK_FILTER_NEAREST, VK_FILTER_NEAREST,
+					VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE, false);
+			}
 		}
 
 		VulkanFlatMapRenderer::~VulkanFlatMapRenderer() {}

Sources/Draw/Vulkan/VulkanImage.cpp

@@ -192,6 +192,10 @@ namespace spades {
 
 		void VulkanImage::CreateSampler(VkFilter magFilter, VkFilter minFilter,
 		                                VkSamplerAddressMode addressMode, bool enableAnisotropy) {
+			if (sampler != VK_NULL_HANDLE) {
+				vkDestroySampler(device->GetDevice(), sampler, nullptr);
+				sampler = VK_NULL_HANDLE;
+			}
 			VkSamplerCreateInfo samplerInfo{};
 			samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
 			samplerInfo.magFilter = magFilter;