-Fixed screen capture for viewports, added a screen capture demo, fixes #1529

demos/viewport/screen_capture/engine.cfg

@@ -0,0 +1,8 @@
+[application]
+
+name="Screen Capturing"
+main_scene="res://screen_capture.scn"
+
+[display]
+
+stretch_mode="2d"

demos/viewport/screen_capture/screen_capture.gd

@@ -0,0 +1,27 @@
+
+extends Control
+
+# member variables here, example:
+# var a=2
+# var b="textvar"
+
+func _ready():
+	# Initialization here
+	pass
+
+
+
+
+func _on_button_pressed():
+	get_viewport().queue_screen_capture()
+	#let two frames pass to make sure the screen was aptured
+	yield(get_tree(),"idle_frame")
+	yield(get_tree(),"idle_frame")
+	#retrieve the captured image
+	var img = get_viewport().get_screen_capture()
+	#create a texture for it
+	var tex = ImageTexture.new()
+	tex.create_from_image(img)
+	#set it to the capture node
+	get_node("capture").set_texture(tex)
+	pass # replace with function body

drivers/gles2/rasterizer_gles2.cpp

@@ -4270,17 +4270,21 @@ void RasterizerGLES2::capture_viewport(Image* r_capture) {
 		glReadPixels( viewport.x, window_size.height-(viewport.height+viewport.y), viewport.width,viewport.height,GL_RGBA,GL_UNSIGNED_BYTE,w.ptr());
 	}
 
-	uint32_t *imgptr = (uint32_t*)w.ptr();
-	for(int y=0;y<(viewport.height/2);y++) {
+	bool flip = current_rt==NULL;
 
-		uint32_t *ptr1 = &imgptr[y*viewport.width];
-		uint32_t *ptr2 = &imgptr[(viewport.height-y-1)*viewport.width];
+	if (flip) {
+		uint32_t *imgptr = (uint32_t*)w.ptr();
+		for(int y=0;y<(viewport.height/2);y++) {
 
-		for(int x=0;x<viewport.width;x++) {
+			uint32_t *ptr1 = &imgptr[y*viewport.width];
+			uint32_t *ptr2 = &imgptr[(viewport.height-y-1)*viewport.width];
 
-			uint32_t tmp = ptr1[x];
-			ptr1[x]=ptr2[x];
-			ptr2[x]=tmp;
+			for(int x=0;x<viewport.width;x++) {
+
+				uint32_t tmp = ptr1[x];
+				ptr1[x]=ptr2[x];
+				ptr2[x]=tmp;
+			}
 		}
 	}