Add SetPreserveImageChannels feature(preserve image channels in stored image file. Only effective when using builtin ImageLoad function(STB image load)).
diff --git a/tiny_gltf.h b/tiny_gltf.h
index 00875f0..1382abf 100644
--- a/tiny_gltf.h
+++ b/tiny_gltf.h
@@ -26,6 +26,7 @@
// THE SOFTWARE.
// Version:
+// - v2.5.0 Add SetPreserveImageChannels() option to load image data as is.
// - v2.4.3 Fix null object output when when material has all default parameters.
// - v2.4.2 Decode percent-encoded URI.
// - v2.4.1 Fix some glTF object class does not have `extensions` and/or
@@ -1190,7 +1191,7 @@
///
typedef bool (*LoadImageDataFunction)(Image *, const int, std::string *,
std::string *, int, int,
- const unsigned char *, int, void *);
+ const unsigned char *, int, void *user_pointer);
///
/// WriteImageDataFunction type. Signature for custom image writing callbacks.
@@ -1347,6 +1348,11 @@
void SetImageLoader(LoadImageDataFunction LoadImageData, void *user_data);
///
+ /// Unset(remove) callback of loading image data
+ ///
+ void RemoveImageLoader();
+
+ ///
/// Set callback to use for writing image data
///
void SetImageWriter(WriteImageDataFunction WriteImageData, void *user_data);
@@ -1384,6 +1390,18 @@
return store_original_json_for_extras_and_extensions_;
}
+ ///
+ /// Specify whether preserve image channales when loading images or not.
+ /// (Not effective when the user suppy their own LoadImageData callbacks)
+ ///
+ void SetPreserveImageChannels(bool onoff) {
+ preserve_image_channels_ = onoff;
+ }
+
+ bool GetPreserveImageChannels() const {
+ return preserve_image_channels_;
+ }
+
private:
///
/// Loads glTF asset from string(memory).
@@ -1403,6 +1421,8 @@
bool store_original_json_for_extras_and_extensions_ = false;
+ bool preserve_image_channels_ = false; /// Default false(expand channels to RGBA) for backward compatibility.
+
FsCallbacks fs = {
#ifndef TINYGLTF_NO_FS
&tinygltf::FileExists, &tinygltf::ExpandFilePath,
@@ -1422,7 +1442,8 @@
#else
nullptr;
#endif
- void *load_image_user_data_ = reinterpret_cast<void *>(&fs);
+ void *load_image_user_data_{nullptr};
+ bool user_image_loader_{false};
WriteImageDataFunction WriteImageData =
#ifndef TINYGLTF_NO_STB_IMAGE_WRITE
@@ -1430,7 +1451,7 @@
#else
nullptr;
#endif
- void *write_image_user_data_ = reinterpret_cast<void *>(&fs);
+ void *write_image_user_data_{nullptr};
};
#ifdef __clang__
@@ -1684,6 +1705,19 @@
namespace tinygltf {
+///
+/// Internal LoadImageDataOption struct.
+/// This struct is passed through `user_pointer` in LoadImageData.
+/// The struct is not passed when the user supply their own LoadImageData callbacks.
+///
+struct LoadImageDataOption
+{
+ // true: preserve image channels(e.g. load as RGB image if the image has RGB channels)
+ // default `false`(channels are expanded to RGBA for backward compatiblity).
+ bool preserve_channels{false};
+
+};
+
// Equals function for Value, for recursivity
static bool Equals(const tinygltf::Value &one, const tinygltf::Value &other) {
if (one.Type() != other.Type()) return false;
@@ -2298,22 +2332,40 @@
void TinyGLTF::SetImageLoader(LoadImageDataFunction func, void *user_data) {
LoadImageData = func;
load_image_user_data_ = user_data;
+ user_image_loader_ = true;
+}
+
+void TinyGLTF::RemoveImageLoader() {
+ LoadImageData =
+#ifndef TINYGLTF_NO_STB_IMAGE
+ &tinygltf::LoadImageData;
+#else
+ nullptr;
+#endif
+
+ load_image_user_data_ = nullptr;
+ user_image_loader_ = false;
}
#ifndef TINYGLTF_NO_STB_IMAGE
bool LoadImageData(Image *image, const int image_idx, std::string *err,
std::string *warn, int req_width, int req_height,
const unsigned char *bytes, int size, void *user_data) {
- (void)user_data;
(void)warn;
+ LoadImageDataOption option;
+ if (user_data) {
+ option = *reinterpret_cast<LoadImageDataOption *>(user_data);
+ }
+
int w = 0, h = 0, comp = 0, req_comp = 0;
unsigned char *data = nullptr;
- // force 32-bit textures for common Vulkan compatibility. It appears that
+ // preserve_channels true: Use channels stored in the image file.
+ // false: force 32-bit textures for common Vulkan compatibility. It appears that
// some GPU drivers do not support 24-bit images for Vulkan
- req_comp = 4;
+ req_comp = option.preserve_channels ? 0 : 4;
int bits = 8;
int pixel_type = TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE;
@@ -2385,13 +2437,18 @@
}
}
+ if (req_comp != 0) {
+ // loaded data has `req_comp` channels(components)
+ comp = req_comp;
+ }
+
image->width = w;
image->height = h;
- image->component = req_comp;
+ image->component = comp;
image->bits = bits;
image->pixel_type = pixel_type;
- image->image.resize(static_cast<size_t>(w * h * req_comp) * size_t(bits / 8));
- std::copy(data, data + w * h * req_comp * (bits / 8), image->image.begin());
+ image->image.resize(static_cast<size_t>(w * h * comp) * size_t(bits / 8));
+ std::copy(data, data + w * h * comp * (bits / 8), image->image.begin());
stbi_image_free(data);
return true;
@@ -5826,6 +5883,18 @@
}
// 11. Parse Image
+ void *load_image_user_data{nullptr};
+
+ LoadImageDataOption load_image_option;
+
+ if (user_image_loader_) {
+ // Use user supplied pointer
+ load_image_user_data = load_image_user_data_;
+ } else {
+ load_image_option.preserve_channels = preserve_image_channels_;
+ load_image_user_data = reinterpret_cast<void *>(&load_image_option);
+ }
+
{
int idx = 0;
bool success = ForEachInArray(v, "images", [&](const json &o) {
@@ -5838,7 +5907,7 @@
Image image;
if (!ParseImage(&image, idx, err, warn, o,
store_original_json_for_extras_and_extensions_, base_dir,
- &fs, &this->LoadImageData, load_image_user_data_)) {
+ &fs, &this->LoadImageData, load_image_user_data)) {
return false;
}
@@ -5876,7 +5945,7 @@
bool ret = LoadImageData(
&image, idx, err, warn, image.width, image.height,
&buffer.data[bufferView.byteOffset],
- static_cast<int>(bufferView.byteLength), load_image_user_data_);
+ static_cast<int>(bufferView.byteLength), load_image_user_data);
if (!ret) {
return false;
}
