Use an offbuffer for the CI screenshot tests (#2751)

* Make the screenshot tests run in an off frame buffer and correct gamma issues in screenshots

* Make the definition of "the same" a bit more flexible to avoid instability in the pipelines

* Restore gamma correction

* Set the colourspace for the off renderTexture

* Set the Srgb for the off renderTexture

* Rebake minor visual changes for off frame buffer

* Update jme3-screenshot-tests/src/main/java/org/jmonkeyengine/screenshottests/testframework/TestDriver.java

Correct to actually compare the scenario with the prime

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* Ensure the fileOutBuf is closed

* Avoid intermediate colour object

* Avoid the wildcard import

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: richardTingle

jme3-screenshot-tests/src/main/java/org/jmonkeyengine/screenshottests/testframework/OffScreenshotAppState.java

@@ -0,0 +1,58 @@
+package org.jmonkeyengine.screenshottests.testframework;
+
+import com.jme3.app.Application;
+import com.jme3.app.state.AbstractAppState;
+import com.jme3.app.state.AppStateManager;
+import com.jme3.renderer.Renderer;
+import com.jme3.system.JmeSystem;
+import com.jme3.texture.FrameBuffer;
+import com.jme3.texture.Texture2D;
+import com.jme3.util.BufferUtils;
+
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.file.Path;
+import java.util.Optional;
+
+public class OffScreenshotAppState extends AbstractAppState{
+
+    private final Texture2D renderTexture;
+    private Renderer renderer;
+    private final FrameBuffer frameBuffer;
+    private Optional<Path> capture = Optional.empty();
+
+    private ByteBuffer outBuf;
+
+    public void takeScreenshot(Path pathToSaveTo) {
+        capture = Optional.of(pathToSaveTo);
+    }
+
+    public OffScreenshotAppState(Texture2D renderTexture, FrameBuffer frameBuffer) {
+        this.renderTexture = renderTexture;
+        this.frameBuffer = frameBuffer;
+    }
+
+    @Override
+    public void initialize(AppStateManager stateManager, Application app) {
+        super.initialize(stateManager, app);
+        renderer = app.getRenderManager().getRenderer();
+        outBuf = BufferUtils.createByteBuffer(renderTexture.getImage().getWidth() * renderTexture.getImage().getHeight() * 4);
+    }
+
+    @Override
+    public void postRender() {
+        super.postRender();
+        if (capture.isPresent()) {
+
+            renderer.readFrameBuffer(frameBuffer, outBuf);
+            try (FileOutputStream fileOutBuf = new FileOutputStream(capture.get().toFile())){
+
+                JmeSystem.writeImageFile(fileOutBuf, "png",outBuf, renderTexture.getImage().getWidth(), renderTexture.getImage().getHeight());
+            }catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            capture = Optional.empty();
+        }
+    }
+}

jme3-screenshot-tests/src/main/java/org/jmonkeyengine/screenshottests/testframework/PixelSamenessDegree.java

@@ -38,7 +38,7 @@
  */
 public enum PixelSamenessDegree{
     SAME(1, null),
-    NEGLIGIBLY_DIFFERENT(1, ColorRGBA.Green),
+    NEGLIGIBLY_DIFFERENT(3, ColorRGBA.Green),
     SUBTLY_DIFFERENT(10, ColorRGBA.Blue),
 
     MEDIUMLY_DIFFERENT(20, ColorRGBA.Yellow),

jme3-screenshot-tests/src/main/java/org/jmonkeyengine/screenshottests/testframework/ScenarioScreenshotRecorder.java

@@ -0,0 +1,35 @@
+package org.jmonkeyengine.screenshottests.testframework;
+
+import java.nio.file.Path;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+public class ScenarioScreenshotRecorder {
+
+    /**
+     * scenario name -> frame number -> screenshot path
+     */
+    Map<String, Map<Integer, Path>> screenshotsAtFrames = new HashMap<>();
+    
+    public void recordScreenshot(String scenarioName, int frameNumber, Path screenshotPath){
+        screenshotsAtFrames.computeIfAbsent(scenarioName, k -> new HashMap<>()).put(frameNumber, screenshotPath);
+    }
+    
+    public Optional<Path> getScreenshotsAtFrame(String scenarioName, int frameNumber){
+        if(!screenshotsAtFrames.containsKey(scenarioName) || !screenshotsAtFrames.get(scenarioName).containsKey(frameNumber)){
+            return Optional.empty();
+        }else{
+            return Optional.of(screenshotsAtFrames.get(scenarioName).get(frameNumber));
+        }
+    }
+    
+    public void addAll(ScenarioScreenshotRecorder other) {
+        for (Map.Entry<String, Map<Integer, Path>> scenarioEntry : other.screenshotsAtFrames.entrySet()) {
+            String scenarioName = scenarioEntry.getKey();
+            for (Map.Entry<Integer, Path> frameEntry : scenarioEntry.getValue().entrySet()) {
+                recordScreenshot(scenarioName, frameEntry.getKey(), frameEntry.getValue());
+            }
+        }
+    }
+}