-Added ability to use cubic interpolation on image resize (little more quality on non-po2 resizing)

-Added ability for exporter to shrink images to non-integer values. Helps if you want to convert your game artwork from 1080->720 or similar

core/image.cpp

@@ -400,6 +400,102 @@ Image::Format Image::get_format() const{
 	return format;
 }
 
+static double _bicubic_interp_kernel( double x ) {
+
+	x = ABS(x);
+
+	double bc = 0;
+
+	if ( x <= 1 )
+		bc = ( 1.5 * x - 2.5 ) * x * x + 1;
+	else if ( x < 2 )
+		bc = ( ( -0.5 * x + 2.5 ) * x - 4 ) * x + 2;
+
+
+	return bc;
+}
+
+template<int CC>
+static void _scale_cubic(const uint8_t* p_src, uint8_t* p_dst, uint32_t p_src_width, uint32_t p_src_height, uint32_t p_dst_width, uint32_t p_dst_height) {
+
+
+	// get source image size
+	int width   = p_src_width;
+	int height  = p_src_height;
+	double xfac = (double) width / p_dst_width;
+	double yfac = (double) height / p_dst_height;
+	// coordinates of source points and cooefficiens
+	double  ox, oy, dx, dy, k1, k2;
+	int     ox1, oy1, ox2, oy2;
+	// destination pixel values
+	// width and height decreased by 1
+	int ymax = height - 1;
+	int xmax = width - 1;
+	// temporary pointer
+
+	for ( int y = 0; y < p_dst_height; y++ ) {
+		// Y coordinates
+		oy  = (double) y * yfac - 0.5f;
+		oy1 = (int) oy;
+		dy  = oy - (double) oy1;
+
+		for ( int x = 0; x < p_dst_width; x++ )	{
+			// X coordinates
+			ox  = (double) x * xfac - 0.5f;
+			ox1 = (int) ox;
+			dx  = ox - (double) ox1;
+
+			// initial pixel value
+
+			uint8_t *dst=p_dst + (y*p_dst_width+x)*CC;
+
+			double color[CC];
+			for(int i=0;i<CC;i++) {
+				color[i]=0;
+			}
+
+
+
+			for ( int n = -1; n < 3; n++ ) {
+				// get Y cooefficient
+				k1 = _bicubic_interp_kernel( dy - (double) n );
+
+				oy2 = oy1 + n;
+				if ( oy2 < 0 )
+					oy2 = 0;
+				if ( oy2 > ymax )
+					oy2 = ymax;
+
+				for ( int m = -1; m < 3; m++ ) {
+					// get X cooefficient
+					k2 = k1 * _bicubic_interp_kernel( (double) m - dx );
+
+					ox2 = ox1 + m;
+					if ( ox2 < 0 )
+						ox2 = 0;
+					if ( ox2 > xmax )
+						ox2 = xmax;
+
+					// get pixel of original image
+					const uint8_t *p = p_src + (oy2 * p_src_width + ox2)*CC;
+
+					for(int i=0;i<CC;i++) {
+
+						color[i]+=p[i]*k2;
+					}
+				}
+			}
+
+			for(int i=0;i<CC;i++) {
+				dst[i]=CLAMP(Math::fast_ftoi(color[i]),0,255);
+			}
+		}
+	}
+}
+
+
+
+
 template<int CC>
 static void _scale_bilinear(const uint8_t* p_src, uint8_t* p_dst, uint32_t p_src_width, uint32_t p_src_height, uint32_t p_dst_width, uint32_t p_dst_height) {
 
@@ -559,6 +655,17 @@ void Image::resize( int p_width, int p_height, Interpolation p_interpolation ) {
 			}
 
 		} break;
+		case INTERPOLATE_CUBIC: {
+
+			switch(get_format_pixel_size(format)) {
+				case 1: _scale_cubic<1>(r_ptr,w_ptr,width,height,p_width,p_height); break;
+				case 2: _scale_cubic<2>(r_ptr,w_ptr,width,height,p_width,p_height); break;
+				case 3: _scale_cubic<3>(r_ptr,w_ptr,width,height,p_width,p_height); break;
+				case 4: _scale_cubic<4>(r_ptr,w_ptr,width,height,p_width,p_height); break;
+			}
+
+		} break;
+
 
 	}
 

core/image.h

@@ -91,6 +91,7 @@ public:
 	
 		INTERPOLATE_NEAREST,
 		INTERPOLATE_BILINEAR,
+		INTERPOLATE_CUBIC,
 		/* INTERPOLATE GAUSS */
 	};
 

tools/editor/editor_import_export.cpp

@@ -1420,12 +1420,12 @@ EditorImportExport::ImageAction EditorImportExport::get_export_image_action() co
 	return image_action;
 }
 
-void EditorImportExport::set_export_image_shrink(int p_shrink) {
+void EditorImportExport::set_export_image_shrink(float p_shrink) {
 
 	image_shrink=p_shrink;
 }
 
-int EditorImportExport::get_export_image_shrink() const{
+float EditorImportExport::get_export_image_shrink() const{
 
 	return image_shrink;
 }
@@ -1496,12 +1496,12 @@ bool EditorImportExport::image_export_group_get_make_atlas(const StringName& p_e
 	return image_groups[p_export_group].make_atlas;
 
 }
-void EditorImportExport::image_export_group_set_shrink(const StringName& p_export_group,int p_amount){
+void EditorImportExport::image_export_group_set_shrink(const StringName& p_export_group,float p_amount){
 	ERR_FAIL_COND(!image_groups.has(p_export_group));
 	image_groups[p_export_group].shrink=p_amount;
 
 }
-int EditorImportExport::image_export_group_get_shrink(const StringName& p_export_group) const{
+float EditorImportExport::image_export_group_get_shrink(const StringName& p_export_group) const{
 
 	ERR_FAIL_COND_V(!image_groups.has(p_export_group),1);
 	return image_groups[p_export_group].shrink;

tools/editor/editor_import_export.h

@@ -252,7 +252,7 @@ protected:
 		ImageAction action;
 		bool make_atlas;
 		float lossy_quality;
-		int shrink;
+		float shrink;
 	};
 
 	Vector<Ref<EditorExportPlugin> > export_plugins;
@@ -260,7 +260,7 @@ protected:
 	Map<String,int> by_idx;
 	ImageAction image_action;
 	float image_action_compress_quality;
-	int image_shrink;
+	float image_shrink;
 	Set<String> image_formats;
 
 	ExportFilter export_filter;
@@ -310,8 +310,8 @@ public:
 	void set_export_image_action(ImageAction p_action);
 	ImageAction get_export_image_action() const;
 
-	void set_export_image_shrink(int p_shrink);
+	void set_export_image_shrink(float p_shrink);
-	int get_export_image_shrink() const;
+	float get_export_image_shrink() const;
 
 	void set_export_image_quality(float p_quality);
 	float get_export_image_quality() const;
@@ -326,8 +326,8 @@ public:
 	ImageAction image_export_group_get_image_action(const StringName& p_export_group) const;
 	void image_export_group_set_make_atlas(const StringName& p_export_group,bool p_make);
 	bool image_export_group_get_make_atlas(const StringName& p_export_group) const;
-	void image_export_group_set_shrink(const StringName& p_export_group,int p_amount);
+	void image_export_group_set_shrink(const StringName& p_export_group,float p_amount);
-	int image_export_group_get_shrink(const StringName& p_export_group) const;
+	float image_export_group_get_shrink(const StringName& p_export_group) const;
 	void image_export_group_set_lossy_quality(const StringName& p_export_group,float p_quality);
 	float image_export_group_get_lossy_quality(const StringName& p_export_group) const;
 

tools/editor/io_plugins/editor_texture_import_plugin.cpp

@@ -828,7 +828,7 @@ Error EditorTextureImportPlugin::import(const String& p_path, const Ref<Resource
 }
 
 
-Error EditorTextureImportPlugin::_process_texture_data(Ref<ImageTexture> &texture,int format, float quality,int flags,EditorExportPlatform::ImageCompression p_compr,int tex_flags,int shrink)  {
+Error EditorTextureImportPlugin::_process_texture_data(Ref<ImageTexture> &texture,int format, float quality,int flags,EditorExportPlatform::ImageCompression p_compr,int tex_flags,float shrink)  {
 
 
 	if (format==IMAGE_FORMAT_COMPRESS_DISK_LOSSLESS || format==IMAGE_FORMAT_COMPRESS_DISK_LOSSY) {
@@ -866,7 +866,7 @@ Error EditorTextureImportPlugin::_process_texture_data(Ref<ImageTexture> &textur
 
 			int orig_w=image.get_width();
 			int orig_h=image.get_height();
-			image.resize(orig_w/shrink,orig_h/shrink);
+			image.resize(orig_w/shrink,orig_h/shrink,Image::INTERPOLATE_CUBIC);
 			texture->create_from_image(image,tex_flags);
 			texture->set_size_override(Size2(orig_w,orig_h));
 
@@ -926,7 +926,7 @@ Error EditorTextureImportPlugin::_process_texture_data(Ref<ImageTexture> &textur
 		int orig_h=image.get_height();
 
 		if (shrink>1) {
-			image.resize(orig_w/shrink,orig_h/shrink);
+			image.resize(orig_w/shrink,orig_h/shrink,Image::INTERPOLATE_CUBIC);
 			texture->create_from_image(image,tex_flags);
 			texture->set_size_override(Size2(orig_w,orig_h));
 		}
@@ -987,7 +987,7 @@ Error EditorTextureImportPlugin::import2(const String& p_path, const Ref<Resourc
 		tex_flags|=Texture::FLAG_ANISOTROPIC_FILTER;
 
 	print_line("path: "+p_path+" flags: "+itos(tex_flags));
-	int shrink=1;
+	float shrink=1;
 	if (from->has_option("shrink"))
 		shrink=from->get_option("shrink");
 

tools/editor/io_plugins/editor_texture_import_plugin.h

@@ -70,7 +70,7 @@ private:
 	static EditorTextureImportPlugin *singleton[MODE_MAX];
 	//used by other importers such as mesh
 
-	Error _process_texture_data(Ref<ImageTexture> &texture, int format, float quality, int flags,EditorExportPlatform::ImageCompression p_compr,int tex_flags,int shrink);
+	Error _process_texture_data(Ref<ImageTexture> &texture, int format, float quality, int flags,EditorExportPlatform::ImageCompression p_compr,int tex_flags,float shrink);
 	void compress_image(EditorExportPlatform::ImageCompression p_mode,Image& image,bool p_smaller);
 public:
 

tools/editor/project_export.cpp

@@ -1156,7 +1156,7 @@ ProjectExportDialog::ProjectExportDialog(EditorNode *p_editor) {
 	image_shrink = memnew( SpinBox );
 	image_shrink->set_min(1);
 	image_shrink->set_max(8);
-	image_shrink->set_step(1);
+	image_shrink->set_step(0.1);
 	image_vb->add_margin_child("Shrink All Images:",image_shrink);
 	sections->add_child(image_vb);
 
@@ -1237,7 +1237,7 @@ ProjectExportDialog::ProjectExportDialog(EditorNode *p_editor) {
 	group_shrink->set_min(1);
 	group_shrink->set_max(8);
 	group_shrink->set_val(1);
-	group_shrink->set_step(1);
+	group_shrink->set_step(0.001);
 	group_options->add_margin_child("Shrink By:",group_shrink);
 	group_shrink->connect("value_changed",this,"_group_changed");