/*

     File: ASCView.m 

 Abstract: A subclass of SCNView on which the user can drop .dae files. It handles mouse events to pick 3D objects and highlight their materials. 

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 */

#import "ASCView.h"

@interface ASCView ()

@property SCNMaterial *selectedMaterial;

@end

@implementation ASCView 

- (void)loadSceneAtURL:(NSURL *)url {

    // Clear any current selection.

    self.selectedMaterial = nil;

    // Load the specified scene. First create a dictionary containing the options we want.

    NSDictionary *options = @{

        // Create normals if absent.

        SCNSceneSourceCreateNormalsIfAbsentKey : @YES,

        // Optimize the rendering by flattening the scene graph when possible. Note that this would prevent you from animating objects independantly.

        SCNSceneSourceFlattenSceneKey : @YES

    };

    // Load and set the scene.

    NSError * __autoreleasing error;

    SCNScene *scene = [SCNScene sceneWithURL:url options:options error:&error];

    if (scene) {

        self.scene = scene;

    }

    else {

        NSLog(@"Problem loading scene from %@\n%@", url, [error localizedDescription]);

    }

}

#pragma mark - Init

- (void)commonInit {

    // Register for the URL pasteboard type.

    [self registerForDraggedTypes:@[NSURLPboardType]];

}

- (id)initWithFrame:(NSRect)frameRect {

    if ((self = [super initWithFrame:frameRect])) {

        [self commonInit];

    }

    return self;

}

- (id)initWithCoder:(NSCoder *)aDecoder {

    if ((self = [super initWithCoder:aDecoder])) {

        [self commonInit];

    }

    return self;

}

#pragma mark - Drag and drop

/*

 Support drag and drop of new dae files.

 */

- (NSDragOperation)dragOperationForPasteboard:(NSPasteboard *)pasteboard {

    // Only support drags from .dae files.

    if ([[pasteboard types] containsObject:NSURLPboardType]) {

        NSURL *fileURL = [NSURL URLFromPasteboard:pasteboard];

        if ([[fileURL pathExtension] isEqualToString:@"dae"]) {

            return NSDragOperationCopy;

        }

    }

    return NSDragOperationNone;

}

- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender {

    return [self dragOperationForPasteboard:[sender draggingPasteboard]];

}

- (NSDragOperation)draggingUpdated:(id <NSDraggingInfo>)sender {

    return [self dragOperationForPasteboard:[sender draggingPasteboard]];

}

- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender {

    NSPasteboard *pasteboard = [sender draggingPasteboard];

    if ([[pasteboard types] containsObject:NSURLPboardType]) {

        NSURL *fileURL = [NSURL URLFromPasteboard:pasteboard];

        [self loadSceneAtURL:fileURL];

        return YES;

    }

    return NO;

}

#pragma mark - Mouse selection

- (void)selectNode:(SCNNode *)node geometryElementIndex:(NSUInteger)index {

    // Unhighlight the previous selection.

    [self.selectedMaterial.emission removeAllAnimations];

    // Clear the selection.

    self.selectedMaterial = nil;

    // Highight the selection, if there is one.

    if (node != nil) {

        // Convert the geometry element index to a material index.

        index = index % [node.geometry.materials count];

        // Make the material unique (i.e. unshared).

        SCNMaterial *unsharedMaterial = [[node.geometry.materials objectAtIndex:index] copy];

        [node.geometry replaceMaterialAtIndex:index withMaterial:unsharedMaterial];

        // Select the material.

        self.selectedMaterial = unsharedMaterial;

        // Animate the material.

        CABasicAnimation *highlightAnimation = [CABasicAnimation animationWithKeyPath:@"contents"];

        highlightAnimation.toValue = [NSColor blueColor];

        highlightAnimation.fromValue = [NSColor blackColor];

        highlightAnimation.repeatCount = MAXFLOAT;

        highlightAnimation.autoreverses = YES;

        highlightAnimation.duration = 0.5;

        highlightAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

        [self.selectedMaterial.emission addAnimation:highlightAnimation forKey:@"highlight"];

    }

}

#pragma mark - Mouse events

- (void)mouseDown:(NSEvent *)event {

    // Convert the mouse location in screen coordinates to local coordinates, then perform a hit test with the local coordinates.

    NSPoint mouseLocation = [self convertPoint:[event locationInWindow] fromView:nil];

    NSArray *hits = [self hitTest:mouseLocation options:nil];

    // If there was a hit, select the nearest object; otherwise unselect.

    if ([hits count] > 0) {

        SCNHitTestResult *hit = hits[0]; // Choose the nearest object hit.

        [self selectNode:hit.node geometryElementIndex:hit.geometryIndex];

    }

    else {

        [self selectNode:nil geometryElementIndex:NSNotFound];

    }

    [super mouseDown:event];

}

@end