toggle srgb on per framebuffer basis (#2729)

Author: riccardobl

jme3-core/src/main/java/com/jme3/renderer/RenderContext.java

@@ -215,6 +215,11 @@ public class RenderContext {
      */
     public FrameBuffer boundFB;
 
+    /**
+     * Convert writes to srgb target from linear space to srgb
+     */
+    public boolean srgbWriteEnabled;
+
     /**
      * Currently bound Renderbuffer.
      *
@@ -412,6 +417,8 @@ private void init() {
         alphaFunc = RenderState.TestFunction.Greater;
         cullMode = RenderState.FaceCullMode.Off;
 
+        srgbWriteEnabled = false;
+
         clearColor.set(0, 0, 0, 0);
     }
 

jme3-core/src/main/java/com/jme3/renderer/opengl/GLRenderer.java

@@ -106,6 +106,7 @@ public final class GLRenderer implements Renderer {
     private int clipX, clipY, clipW, clipH;
     private int defaultAnisotropicFilter = 1;
     private boolean linearizeSrgbImages;
+    private boolean mainFrameBufferSrgb;
     private HashSet<String> extensions;
     private boolean generateMipmapsForFramebuffers = true;
 
@@ -1916,6 +1917,7 @@ public void copyFrameBuffer(FrameBuffer src, FrameBuffer dst, boolean copyColor,
             int dstY1;
 
             int prevFBO = context.boundFBO;
+            FrameBuffer prevFB = context.boundFB;
 
             if (mainFbOverride != null) {
                 if (src == null) {
@@ -1957,6 +1959,8 @@ public void copyFrameBuffer(FrameBuffer src, FrameBuffer dst, boolean copyColor,
                 dstY1 = dst.getHeight();
             }
 
+            toggleFramebufferSrgb(dst);
+
             int mask = 0;
 
             if(copyColor){
@@ -1973,6 +1977,9 @@ public void copyFrameBuffer(FrameBuffer src, FrameBuffer dst, boolean copyColor,
 
 
             glfbo.glBindFramebufferEXT(GLFbo.GL_FRAMEBUFFER_EXT, prevFBO);
+            context.boundFBO = prevFBO;
+            context.boundFB = prevFB;
+            toggleFramebufferSrgb(prevFB);
         } else {
             throw new RendererException("Framebuffer blitting not supported by the video hardware");
         }
@@ -2133,6 +2140,21 @@ private void bindFrameBuffer(FrameBuffer fb) {
         }
     }
 
+    private void toggleFramebufferSrgb(FrameBuffer fb) {
+        boolean isSrgb = fb == null ? mainFrameBufferSrgb : fb.isSrgb();
+
+        if (isSrgb != context.srgbWriteEnabled) {
+            if (caps.contains(Caps.Srgb)) {
+                if (isSrgb) {
+                    gl.glEnable(GLExt.GL_FRAMEBUFFER_SRGB_EXT);
+                } else {
+                    gl.glDisable(GLExt.GL_FRAMEBUFFER_SRGB_EXT);
+                }
+                context.srgbWriteEnabled = isSrgb;
+            }
+        }
+    }
+
     public void updateFrameBuffer(FrameBuffer fb) {
         if (fb.getNumColorBuffers() == 0 && fb.getDepthBuffer() == null) {
             throw new IllegalArgumentException("The framebuffer: " + fb
@@ -2266,6 +2288,7 @@ public void setFrameBuffer(FrameBuffer fb) {
 
         if (context.boundFB == fb) {
             if (fb == null || !fb.isUpdateNeeded()) {
+                toggleFramebufferSrgb(fb);
                 return;
             }
         }
@@ -2317,6 +2340,7 @@ public void setFrameBuffer(FrameBuffer fb) {
                 if (fb.getName() != null) glext.glObjectLabel(GL3.GL_FRAMEBUFFER, fb.getId(), fb.getName());
             }
         }
+        toggleFramebufferSrgb(fb);
     }
 
     @Override
@@ -3574,17 +3598,13 @@ public void setMainFrameBufferSrgb(boolean enableSrgb) {
             logger.warning("sRGB framebuffer is not supported " +
                     "by video hardware, but was requested.");
 
+            mainFrameBufferSrgb = false;
             return;
         }
 
-        setFrameBuffer(null);
-
-        if (enableSrgb) {
-            gl.glEnable(GLExt.GL_FRAMEBUFFER_SRGB_EXT);
-            logger.log(Level.FINER, "sRGB FrameBuffer enabled (Gamma Correction)");
-        } else {
-            gl.glDisable(GLExt.GL_FRAMEBUFFER_SRGB_EXT);
-			logger.log(Level.FINER, "sRGB FrameBuffer disabled (Gamma Correction)");
+        mainFrameBufferSrgb = enableSrgb;
+        if (context.boundFB == null) {
+            toggleFramebufferSrgb(null);
         }
     }
 
@@ -3682,7 +3702,7 @@ public boolean isMainFrameBufferSrgb() {
         if (!caps.contains(Caps.Srgb)) {
             return false;
         } else {
-            return gl.glIsEnabled(GLExt.GL_FRAMEBUFFER_SRGB_EXT);
+            return mainFrameBufferSrgb;
         }
     }