Add `etcpak` library for faster ETC/ETC2/S3TC imports.

- `etc` module was renamed to `etcpak` and modified to use the new library.
- PKM importer is removed in the process, it's obsolete.
- Old library `etc2comp` is removed.
- S3TC compression no longer done via `squish` (but decompression still is).
- Slight modifications to etcpak sources for MinGW compatibility,
  to fix LLVM `-Wc++11-narrowing` errors, and to allow using vendored or
  system libpng.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/thirdparty/etcpak/Error.cpp b/thirdparty/etcpak/Error.cpp
new file mode 100644
index 0000000000..014ecdab66
--- /dev/null
+++ b/thirdparty/etcpak/Error.cpp
@@ -0,0 +1,48 @@
+#include <stdint.h>
+
+#include "Error.hpp"
+#include "Math.hpp"
+
+float CalcMSE3( const Bitmap& bmp, const Bitmap& out )
+{
+    float err = 0;
+
+    const uint32_t* p1 = bmp.Data();
+    const uint32_t* p2 = out.Data();
+    size_t cnt = bmp.Size().x * bmp.Size().y;
+
+    for( size_t i=0; i<cnt; i++ )
+    {
+        uint32_t c1 = *p1++;
+        uint32_t c2 = *p2++;
+
+        err += sq( ( c1 & 0x000000FF ) - ( c2 & 0x000000FF ) );
+        err += sq( ( ( c1 & 0x0000FF00 ) >> 8 ) - ( ( c2 & 0x0000FF00 ) >> 8 ) );
+        err += sq( ( ( c1 & 0x00FF0000 ) >> 16 ) - ( ( c2 & 0x00FF0000 ) >> 16 ) );
+    }
+
+    err /= cnt * 3;
+
+    return err;
+}
+
+float CalcMSE1( const Bitmap& bmp, const Bitmap& out )
+{
+    float err = 0;
+
+    const uint32_t* p1 = bmp.Data();
+    const uint32_t* p2 = out.Data();
+    size_t cnt = bmp.Size().x * bmp.Size().y;
+
+    for( size_t i=0; i<cnt; i++ )
+    {
+        uint32_t c1 = *p1++;
+        uint32_t c2 = *p2++;
+
+        err += sq( ( c1 >> 24 ) - ( c2 & 0xFF ) );
+    }
+
+    err /= cnt;
+
+    return err;
+}