[Request] Make vkd3d cache naming more like DXVK in behavior.

[shelterx]

I use VKD3D_SHADER_CACHE_PATH to set a fixed path for the shader cache because I don't want the shaders in the program directories all over. However it's such a hassle to do this for each game, since sharing shader cache file isn't really a great idea.

I made a Proof of concept patch here so the cache name is the same as the program/app-name, it seems to work for me, but I am by no means a C programmer, but you get the idea.

--- a/libs/vkd3d/cache.c     2024-03-13 10:32:06.481920565 +0100
+++ b/libs/vkd3d/cache.c     2024-03-13 10:31:57.489923606 +0100
@@ -3147,6 +3147,9 @@
         struct d3d12_device *device)
 {
     char path_buf[VKD3D_PATH_MAX];
+    char app[VKD3D_PATH_MAX];
+    char *cachename;
+
     VKD3D_UNUSED size_t i, n;
     const char *separator;
     const char *path;
@@ -3178,13 +3181,17 @@
      * Seems to be related to drive detection (Rename fails with drive mismatch in some cases for example).
      * Manually remap Unix style paths to conservative Win32.
      * Normally Wine accepts Unix style paths, but not here for whatever reason. */
+    if (!vkd3d_get_program_name(app))
+       cachename = "vkd3d-proton-cache";
+    else
+       cachename = strcat(app, "-cache");

     if (path && path[0] == '/')
-        snprintf(cache->read_path, sizeof(cache->read_path), "Z:\\%s%svkd3d-proton.cache", path + 1, separator);
+        snprintf(cache->read_path, sizeof(cache->read_path), "Z:\\%s%s%s", path + 1, separator, cachename);
     else if (path)
-        snprintf(cache->read_path, sizeof(cache->read_path), "%s%svkd3d-proton.cache", path, separator);
+        snprintf(cache->read_path, sizeof(cache->read_path), "%s%s%s", path, separator, cachename);
     else
-        strcpy(cache->read_path, "vkd3d-proton.cache");
+        strcpy(cache->read_path, cachename);

     for (i = 0, n = strlen(cache->read_path); i < n; i++)
         if (cache->read_path[i] == '/')
@@ -3192,9 +3199,9 @@
     INFO("Remapping VKD3D_SHADER_CACHE to: %s.\n", cache->read_path);
 #else
     if (path)
-        snprintf(cache->read_path, sizeof(cache->read_path), "%s%svkd3d-proton.cache", path, separator);
+        snprintf(cache->read_path, sizeof(cache->read_path), "%s%s%s", path, separator, cachename);
     else
-        strcpy(cache->read_path, "vkd3d-proton.cache");
+        strcpy(cache->read_path, cachename);
 #endif

     INFO("Attempting to load disk cache from: %s.\n", cache->read_path);