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Add flipY option to StbImageLoader public API #2758

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Merged
riccardobl merged 4 commits into from
May 10, 2026
+114 −82
Merged

Add flipY option to StbImageLoader public API #2758

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4a3768d
Initial plan
Copilot May 9, 2026
5c271b9
Add flipY option to StbImageLoader, update MipMapGenerator and TestBi…
Copilot May 9, 2026
280102e
Fix code style: add spaces after if keyword in StbImageLoader
Copilot May 9, 2026
09d0764
Revert MipMapGenerator.java to keep AWTLoader as requested
Copilot May 9, 2026
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15 changes: 12 additions & 3 deletions jme3-examples/src/main/java/jme3test/gui/TestBitmapFontLayout.java
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,11 @@
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.*;
import javax.imageio.ImageIO;

import com.jme3.app.DebugKeysAppState;
import com.jme3.app.StatsAppState;
Expand All @@ -64,7 +67,7 @@
import com.jme3.texture.Image;
import com.jme3.texture.Texture;
import com.jme3.texture.Texture2D;
import com.jme3.texture.plugins.AWTLoader;
import com.jme3.texture.plugins.StbImageLoader;

/**
*
Expand Down Expand Up @@ -152,8 +155,14 @@ private Texture renderAwtFont( TestConfig test, int width, int height, BitmapFon

g2.dispose();

Image jmeImage = new AWTLoader().load(image, true);
return new Texture2D(jmeImage);
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, "png", baos);
Image jmeImage = new StbImageLoader().load(new ByteArrayInputStream(baos.toByteArray()), true);
return new Texture2D(jmeImage);
} catch (IOException e) {
throw new RuntimeException("Failed to convert AWT image to jME Image", e);
}
}

private Node createVisual( TestConfig test ) {
Expand Down
181 changes: 102 additions & 79 deletions jme3-plugins/src/main/java/com/jme3/texture/plugins/StbImageLoader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,107 @@
public class StbImageLoader implements AssetLoader {
private final StbImage stbImage = new StbImage(BufferUtils::createByteBuffer);

/**
* Loads an image from an {@link InputStream} with optional vertical flip.
*
* @param in the input stream containing the encoded image data (e.g. PNG, JPEG)
* @param flipY {@code true} to flip the image vertically on load
* @return the decoded {@link Image}
* @throws IOException if the stream cannot be read or the image format is unsupported
*/
public Image load(InputStream in, boolean flipY) throws IOException {
byte[] data = ByteUtils.getByteContent(in);
return load(data, flipY);
}

/**
* Loads an image from a byte array with optional vertical flip.
*
* @param data the raw encoded image data (e.g. PNG, JPEG)
* @param flipY {@code true} to flip the image vertically on load
* @return the decoded {@link Image}
* @throws IOException if the image data cannot be decoded or the format is unsupported
*/
public Image load(byte[] data, boolean flipY) throws IOException {
ByteBuffer buffer = ByteBuffer.wrap(data);
stbImage.setConvertIphonePngToRgb(true);
stbImage.setUnpremultiplyOnLoad(true);

StbDecoder decoder = stbImage.getDecoder(buffer, flipY);
StbImageInfo info = decoder.info();
int channels = info.getChannels();

int width = info.getWidth();
int height = info.getHeight();
int desiredChannels = channels;

boolean is16bit = info.is16Bit();
boolean isFloat = info.isFloat();
boolean sRGB = false;


Image.Format jmeFormat;
if (is16bit || isFloat) {
switch (channels) {
case 1:
jmeFormat = Image.Format.Luminance16F;
desiredChannels = 1;
break;
case 2:
jmeFormat = Image.Format.Luminance16FAlpha16F;
desiredChannels = 2;
break;
case 3:
jmeFormat = Image.Format.RGB16F;
desiredChannels = 3;
break;
case 4:
jmeFormat = Image.Format.RGBA16F;
desiredChannels = 4;
break;
default:
throw new IOException("Unsupported number of channels: " + channels);

}
} else {
switch (channels) {
case 1:
jmeFormat = Image.Format.Luminance8;
desiredChannels = 1;
break;
case 2:
jmeFormat = Image.Format.Luminance8Alpha8;
desiredChannels = 2;
break;
case 3:
jmeFormat = Image.Format.RGB8;
desiredChannels = 3;
sRGB = true;
break;
case 4:
jmeFormat = Image.Format.RGBA8;
desiredChannels = 4;
sRGB = true;
break;
default:
throw new IOException("Unsupported number of channels: " + channels);
}
}

StbImageResult imgData;
if (isFloat){
imgData = decoder.loadf(desiredChannels);
} else if (is16bit){
imgData = decoder.load16(desiredChannels);
} else {
imgData = decoder.load(desiredChannels);
}

ByteBuffer jmeImageBuffer = convertImageData(imgData, jmeFormat);

return new Image(jmeFormat, width, height, jmeImageBuffer, sRGB ? ColorSpace.sRGB : ColorSpace.Linear);
}

@Override
public Object load(AssetInfo assetInfo) throws IOException {
AssetKey<?> key = assetInfo.getKey();
Expand All @@ -33,85 +134,7 @@ public Object load(AssetInfo assetInfo) throws IOException {
boolean flip = textureKey != null && textureKey.isFlipY();

try(InputStream is = assetInfo.openStream()) {
byte[] data = ByteUtils.getByteContent(is);
ByteBuffer buffer = ByteBuffer.wrap(data);
stbImage.setConvertIphonePngToRgb(true);
stbImage.setUnpremultiplyOnLoad(true);

StbDecoder decoder = stbImage.getDecoder(buffer, flip);
StbImageInfo info = decoder.info();
int channels = info.getChannels();

int width = info.getWidth();
int height = info.getHeight();
int desiredChannels = channels;

boolean is16bit = info.is16Bit();
boolean isFloat = info.isFloat();
boolean sRGB = false;


Image.Format jmeFormat;
if (is16bit || isFloat) {
switch (channels) {
case 1:
jmeFormat = Image.Format.Luminance16F;
desiredChannels = 1;
break;
case 2:
jmeFormat = Image.Format.Luminance16FAlpha16F;
desiredChannels = 2;
break;
case 3:
jmeFormat = Image.Format.RGB16F;
desiredChannels = 3;
break;
case 4:
jmeFormat = Image.Format.RGBA16F;
desiredChannels = 4;
break;
default:
throw new IOException("Unsupported number of channels: " + channels);

}
} else {
switch (channels) {
case 1:
jmeFormat = Image.Format.Luminance8;
desiredChannels = 1;
break;
case 2:
jmeFormat = Image.Format.Luminance8Alpha8;
desiredChannels = 2;
break;
case 3:
jmeFormat = Image.Format.RGB8;
desiredChannels = 3;
sRGB = true;
break;
case 4:
jmeFormat = Image.Format.RGBA8;
desiredChannels = 4;
sRGB = true;
break;
default:
throw new IOException("Unsupported number of channels: " + channels);
}
}

StbImageResult imgData;
if(isFloat){
imgData = decoder.loadf(desiredChannels);
} else if(is16bit){
imgData = decoder.load16(desiredChannels);
} else {
imgData = decoder.load(desiredChannels);
}

ByteBuffer jmeImageBuffer = convertImageData(imgData, jmeFormat);

Image jmeImage = new Image(jmeFormat, width, height, jmeImageBuffer, sRGB ? ColorSpace.sRGB : ColorSpace.Linear);
return jmeImage;
return load(is, flip);
}
}

Expand Down
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