fix(iff): Improved IFF support reading and writing z buffers (#4673)

Added support for reading and writing ZBUF chunks, also known as
Z-buffers or depth maps.
Removed noproxy versions, no longer needed.

---------

Signed-off-by: Mikael Sundell <mikael.sundell@gmail.com>

Author: mikaelsundell

src/iff.imageio/CMakeLists.txt

@@ -2,9 +2,4 @@
 # SPDX-License-Identifier: Apache-2.0
 # https://github.com/AcademySoftwareFoundation/OpenImageIO
 
-option (ENABLE_RLA_IOPROXY "(Temporarily) turn this off to switch back to the old pre-IOProxy RLA implementation to address a bug." ON)
-if (ENABLE_RLA_IOPROXY)
-    add_oiio_plugin (iffinput.cpp iffoutput.cpp)
-else ()
-    add_oiio_plugin (noproxy-iffinput.cpp noproxy-iffoutput.cpp noproxy-iff_pvt.cpp)
-endif ()
+add_oiio_plugin (iffinput.cpp iffoutput.cpp)

src/iff.imageio/iff_pvt.h

@@ -4,8 +4,13 @@
 
 #pragma once
 
-// Format reference: Affine Toolkit (Thomas E. Burge), riff.h and riff.c
-//                   Autodesk Maya documentation, ilib.h
+// Maya Fileformats Version 6:
+//   https://courses.cs.washington.edu/courses/cse458/05au/help/mayaguide/Reference/FileFormats.pdf
+// Format reference: Affine Toolkit (Thomas E. Burge):
+//   riff.h and riff.c
+// Autodesk Maya documentation:
+//   ilib.h
+
 
 #include <cstdio>
 
@@ -36,16 +41,19 @@ const uint32_t BLACK   = 0x00000010;
 class IffFileHeader {
 public:
     // header information
-    uint32_t x;
-    uint32_t y;
-    uint32_t width;
-    uint32_t height;
-    uint32_t compression;
-    uint8_t pixel_bits;
-    uint8_t pixel_channels;
-    uint16_t tiles;
-    uint16_t tile_width;
-    uint16_t tile_height;
+    uint32_t x           = 0;
+    uint32_t y           = 0;
+    uint32_t z           = 0;
+    uint32_t width       = 0;
+    uint32_t height      = 0;
+    uint32_t compression = 0;
+    uint8_t rgba_bits    = 0;
+    uint8_t rgba_count   = 0;
+    uint16_t tiles       = 0;
+    uint16_t tile_width  = 0;
+    uint16_t tile_height = 0;
+    uint8_t zbuffer      = 0;
+    uint8_t zbuffer_bits = 0;
 
     // author string
     std::string author;
@@ -59,14 +67,29 @@ class IffFileHeader {
     // for4 start
     uint32_t for4_start;
 
-private:
-};
+    size_t channel_bytes() const { return (rgba_bits / 8); }
+
+    size_t rgba_channels_bytes() const { return channel_bytes() * rgba_count; }
+
+    size_t rgba_scanline_bytes() const { return width * rgba_channels_bytes(); }
+
+    size_t zbuffer_bytes() const { return zbuffer ? (zbuffer_bits / 8) : 0; }
 
+    size_t zbuffer_scanline_bytes() const { return width * zbuffer_bytes(); }
 
+    size_t scanline_bytes() const { return width * pixel_bytes(); }
+
+    size_t pixel_bytes() const
+    {
+        return rgba_channels_bytes() + zbuffer_bytes();
+    }
+
+    size_t image_bytes() const { return pixel_bytes() * width * height; }
+};
 
-// align size
+// align chunk
 inline uint32_t
-align_size(uint32_t size, uint32_t alignment)
+align_chunk(uint32_t size, uint32_t alignment)
 {
     uint32_t mod = size % alignment;
     if (mod) {