New RAPageNode rendering method

New RAPageNode rendering method separates paging in/out with page
switching, so the page generation can occur on a background thread.
Still have to work out some kinks related to updating geometries on a
separate thread.

DRAppDelegate.m

@@ -10,7 +10,7 @@
 
 #import "RASceneGraphController.h"
 
-#define IMAGERY_DATASET 2
+#define IMAGERY_DATASET 1
 #define TERRAIN_DATASET 1
 
 

EarthViewExample.xcodeproj/project.pbxproj

@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		9109E03C153D86100008286D /* star1.png in Resources */ = {isa = PBXBuildFile; fileRef = 9109E03B153D86100008286D /* star1.png */; };
 		9109E03E153D864F0008286D /* RASceneGraphController.m in Sources */ = {isa = PBXBuildFile; fileRef = 9109E03D153D864F0008286D /* RASceneGraphController.m */; };
+		916EEB8D1552D4E800951ACC /* RAPageNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 916EEB8C1552D4E800951ACC /* RAPageNode.m */; };
 		91C9975C1548E1BF00B69A8A /* Icon114.png in Resources */ = {isa = PBXBuildFile; fileRef = 91C9975B1548E1BF00B69A8A /* Icon114.png */; };
 		91C9975E1548E1F000B69A8A /* Icon57.png in Resources */ = {isa = PBXBuildFile; fileRef = 91C9975D1548E1F000B69A8A /* Icon57.png */; };
 		91C997601548E21400B69A8A /* Icon144.png in Resources */ = {isa = PBXBuildFile; fileRef = 91C9975F1548E21400B69A8A /* Icon144.png */; };
@@ -49,6 +50,8 @@
 /* Begin PBXFileReference section */
 		9109E03B153D86100008286D /* star1.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = star1.png; sourceTree = "<group>"; };
 		9109E03D153D864F0008286D /* RASceneGraphController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RASceneGraphController.m; sourceTree = "<group>"; };
+		916EEB8B1552D4E800951ACC /* RAPageNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RAPageNode.h; sourceTree = "<group>"; };
+		916EEB8C1552D4E800951ACC /* RAPageNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RAPageNode.m; sourceTree = "<group>"; };
 		91BBDFB1153A49A900CEF4BA /* README.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = README.md; sourceTree = SOURCE_ROOT; };
 		91C9975B1548E1BF00B69A8A /* Icon114.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = Icon114.png; sourceTree = "<group>"; };
 		91C9975D1548E1F000B69A8A /* Icon57.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = Icon57.png; sourceTree = "<group>"; };
@@ -214,6 +217,8 @@
 				91F77E631539341B00F8AE05 /* RANodeVisitor.m */,
 				91F77E641539341B00F8AE05 /* RAPage.h */,
 				91F77E651539341B00F8AE05 /* RAPage.m */,
+				916EEB8B1552D4E800951ACC /* RAPageNode.h */,
+				916EEB8C1552D4E800951ACC /* RAPageNode.m */,
 				91F77E661539341B00F8AE05 /* RARenderVisitor.h */,
 				91F77E671539341B00F8AE05 /* RARenderVisitor.m */,
 				91F77E681539341B00F8AE05 /* RASceneGraphController.h */,
@@ -341,6 +346,7 @@
 				91F77E981539C31E00F8AE05 /* RAGeographicUtils.c in Sources */,
 				9109E03E153D864F0008286D /* RASceneGraphController.m in Sources */,
 				91F22019154C7B4700A5F74E /* RAShaderProgram.m in Sources */,
+				916EEB8D1552D4E800951ACC /* RAPageNode.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

EarthViewExample.xcodeproj/xcuserdata/ross.xcuserdatad/xcdebugger/Breakpoints.xcbkptlist

@@ -2,6 +2,21 @@
 <Bucket
    type = "1"
    version = "1.0">
+   <FileBreakpoints>
+      <FileBreakpoint
+         shouldBeEnabled = "Yes"
+         ignoreCount = "0"
+         continueAfterRunningActions = "No"
+         filePath = "Source/RATilePager.m"
+         timestampString = "357770597.47682"
+         startingColumnNumber = "9223372036854775807"
+         endingColumnNumber = "9223372036854775807"
+         startingLineNumber = "352"
+         endingLineNumber = "352"
+         landmarkName = "-requestPage:"
+         landmarkType = "5">
+      </FileBreakpoint>
+   </FileBreakpoints>
    <ExceptionBreakpoints>
       <ExceptionBreakpoint
          shouldBeEnabled = "Yes"

Source/RAGeometry.m

@@ -120,12 +120,12 @@ - (void)setObjectData:(const void *)data withSize:(NSUInteger)length withStride:
     @synchronized(self) {
         _vertexData = [NSMutableData dataWithBytes:data length:length];
         _vertexStride = stride;
+
+        // force re-gen of vertex buffer
+        _vertexDataDirty = YES;
     }
 
     [self dirtyBound];
-
-    // force re-gen of vertex buffer
-    _vertexDataDirty = YES;
 }
 
 - (void)setIndexData:(const void *)data withSize:(NSUInteger)length withStride:(NSUInteger)stride
@@ -135,12 +135,12 @@ - (void)setIndexData:(const void *)data withSize:(NSUInteger)length withStride:(
     @synchronized(self) {
         _indexData = [NSMutableData dataWithBytes:data length:length];
         _indexStride = stride;
+
+        // force re-gen of index buffer
+        _indexDataDirty = YES;
     }
 
     [self dirtyBound];
-
-    // force re-gen of index buffer
-    _indexDataDirty = YES;
 }
 
 - (void)setupGL
@@ -212,6 +212,7 @@ - (void)setupGL
         }
 
         glBindVertexArrayOES(0);
+        //glFlush();
     }
 }
 

Source/RAGroup.h

@@ -12,7 +12,7 @@
     NSMutableArray * _children;
 }
 
-@property (readonly) NSArray * children;
+@property (readonly, atomic) NSArray * children;
 
 - (void)addChild:(RANode *)node;
 - (void)removeChild:(RANode *)node;

Source/RANodeVisitor.h

@@ -13,6 +13,7 @@
 #import "RAGroup.h"
 #import "RATransform.h"
 #import "RAGeometry.h"
+#import "RAPageNode.h"
 
 
 @interface RANodeVisitor : NSObject {
@@ -29,5 +30,6 @@
 - (void)applyGroup:(RAGroup *)node;
 - (void)applyTransform:(RATransform *)node;
 - (void)applyGeometry:(RAGeometry *)node;
+- (void)applyPageNode:(RAPageNode *)node;
 
 @end

Source/RANodeVisitor.m

@@ -70,4 +70,9 @@ - (void)applyGeometry:(RAGeometry *)node
     [self applyNode: node];
 }
 
+- (void)applyPageNode:(RAPageNode *)node
+{
+    [self applyNode: node];
+}
+
 @end

Source/RAPage.h

@@ -11,6 +11,7 @@
 #import "RAGeographicUtils.h"
 #import "RABoundingSphere.h"
 #import "RAGeometry.h"
+#import "RACamera.h"
 #import "RATileDatabase.h"
 
 
@@ -40,4 +41,8 @@
 
 - (void)setCenter:(GLKVector3)center andRadius:(double)radius;
 
+- (float)calculateTiltWithCamera:(RACamera *)camera;
+- (float)calculateScreenSpaceErrorWithCamera:(RACamera *)camera;
+- (BOOL)isOnscreenWithCamera:(RACamera *)camera;
+
 @end

Source/RAPage.m

@@ -11,9 +11,6 @@
 @implementation RAPage {
     RABoundingSphere *  _bound;
     RAPage *            _parent;
-
-    NSURLConnection *   _connection;
-    NSMutableData *     _imageData;
 }
 
 @synthesize tile, key;
@@ -35,7 +32,9 @@ - (RAPage *)initWithTileID:(TileID)t andParent:(RAPage *)parent;
 }
 
 - (void)dealloc {
-    [_connection cancel];
+    [imageryLoadOp cancel];
+    [terrainLoadOp cancel];
+    [updatePageOp cancel];
 }
 
 - (void)setCenter:(GLKVector3)center andRadius:(double)radius {
@@ -44,4 +43,39 @@ - (void)setCenter:(GLKVector3)center andRadius:(double)radius {
     _bound.radius = radius;
 }
 
+- (float)calculateTiltWithCamera:(RACamera *)camera {
+    // calculate dot product between page normal and camera vector
+    const GLKVector3 unitZ = { 0, 0, -1 };
+    GLKVector3 pageNormal = GLKVector3Normalize(self.bound.center);
+    GLKVector3 cameraLook = GLKVector3Normalize(GLKMatrix4MultiplyAndProjectVector3( GLKMatrix4Invert(camera.modelViewMatrix, NULL), unitZ ));
+    return GLKVector3DotProduct(pageNormal, cameraLook);
+}
+
+- (float)calculateScreenSpaceErrorWithCamera:(RACamera *)camera {
+    // !!! this does not work so well on large, curved pages
+    // in this case, should test all four corners of the tile and take min distance
+    GLKVector3 center = GLKMatrix4MultiplyAndProjectVector3( camera.modelViewMatrix, self.bound.center );
+    double distance = GLKVector3Length(center);
+    //double distance = -center.z;  // seem like this should be more accurate, but the math clearing isn't quite right, as it favors pages near the equator
+
+    // !!! this should be based upon the Camera parameters
+    double theta = GLKMathDegreesToRadians(65.0f);
+    double w = 2. * distance * tan(theta/2.);
+
+    // convert object error to screen error
+    double x = 1024;    // screen size
+    double epsilon = ( 2. * self.bound.radius ) / 256.;    // object error
+    return ( epsilon * x ) / w;
+}
+
+- (BOOL)isOnscreenWithCamera:(RACamera *)camera {
+    GLKMatrix4 modelViewProjectionMatrix = GLKMatrix4Multiply( camera.projectionMatrix, camera.modelViewMatrix );
+
+    RABoundingSphere * sb = [self.bound transform:modelViewProjectionMatrix];
+    if ( sb.center.x + sb.radius < -1.5 || sb.center.x - sb.radius > 1.5 ) return NO;
+    if ( sb.center.y + sb.radius < -1.5 || sb.center.y - sb.radius > 1.5 ) return NO;
+
+    return YES;
+}
+
 @end

Source/RAPageNode.h

@@ -0,0 +1,17 @@
+//
+//  RAPageNode.h
+//  EarthViewExample
+//
+//  Created by Ross Anderson on 5/3/12.
+//  Copyright (c) 2012 Ross Anderson. All rights reserved.
+//
+
+#import "RANode.h"
+
+#import "RAPage.h"
+
+@interface RAPageNode : RANode
+
+@property (strong, nonatomic) RAPage * page;
+
+@end

Source/RAPageNode.m

@@ -0,0 +1,33 @@
+//
+//  RAPageNode.m
+//  EarthViewExample
+//
+//  Created by Ross Anderson on 5/3/12.
+//  Copyright (c) 2012 Ross Anderson. All rights reserved.
+//
+
+#import "RAPageNode.h"
+
+@implementation RAPageNode
+
+@synthesize page = _page;
+
+
+- (SEL)visitorSelector {
+    return @selector(applyPageNode:);
+}
+
+- (void)calculateBound {
+    _bound = self.page.bound;
+}
+
+- (RAPage *)page {
+    return _page;
+}
+
+- (void)setPage:(RAPage *)page {
+    _page = page;
+    [self dirtyBound];
+}
+
+@end

Source/RARenderVisitor.m

@@ -170,4 +170,42 @@ - (void)applyGeometry:(RAGeometry *)node
     [renderQueue addObject: data];
 }
 
+- (void)applyPageNode:(RAPageNode *)node
+{
+    [self traversePage: node.page];
+}
+
+- (void)traversePage:(RAPage *)page {
+    // is the page facing away from the camera?
+    if ( [page calculateTiltWithCamera:self.camera] < -0.5f ) return;
+
+    float texelError = 0.0f;
+    texelError = [page calculateScreenSpaceErrorWithCamera:self.camera];
+
+    // should we choose to display this page?
+    if ( texelError < 3.f && page.geometry ) {
+        // don't bother traversing if we are offscreen
+        if ( ! [page isOnscreenWithCamera:self.camera] ) return;
+
+        [self applyGeometry: page.geometry];
+        return;
+    }
+
+    // are the children available?
+    if ( page.child1.geometry && page.child2.geometry && page.child3.geometry && page.child4.geometry ) {
+        // traverse children
+        [self traversePage: page.child1];
+        [self traversePage: page.child2];
+        [self traversePage: page.child3];
+        [self traversePage: page.child4];
+    } else {
+        // don't bother traversing if we are offscreen
+        if ( ! [page isOnscreenWithCamera:self.camera] ) return;
+
+        [self applyGeometry: page.geometry];
+        return;
+    }
+}
+
+
 @end

Source/RASceneGraphController.m

@@ -116,8 +116,8 @@ - (void)viewDidLoad
 
     manipulator.view = self.view;
 
-    // create another context to load textures into
-    self.pager.loadingContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2 sharegroup:[context sharegroup]];
+    // create another context for threaded operations
+    self.pager.auxilliaryContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2 sharegroup:[context sharegroup]];
 
     [self.pager setup];
     [self setupGL];
@@ -225,7 +225,7 @@ - (RAGeometry *)makeBoxWithHalfWidth:(GLfloat)half
 - (RANode *)createBlueMarble
 {
     RAGroup * root = [RAGroup new];
-    [root addChild: self.pager.nodes];
+    [root addChild: self.pager.rootNode];
 
     return root;
 }
@@ -313,7 +313,7 @@ - (void)update
     skybox.transform.projectionMatrix = projectionMatrix;
     skybox.transform.modelviewMatrix = self.camera.modelViewMatrix;
 
-    [self.pager updateSceneGraph];
+    [self.pager update];
 }
 
 - (void)glkView:(GLKView *)view drawInRect:(CGRect)rect

Source/RATilePager.h

@@ -21,13 +21,13 @@
 
 @property (strong) RATileDatabase * imageryDatabase;
 @property (strong) RATileDatabase * terrainDatabase;
-@property (strong) EAGLContext * loadingContext;
+@property (strong) EAGLContext * auxilliaryContext;
 
-@property (readonly) RAGroup * nodes;
+@property (readonly) RAGroup * rootNode;
 @property (readonly) NSSet * rootPages;
 @property (strong) RACamera * camera;
 
 - (void)setup;  // call once the databases are configured
-- (void)updateSceneGraph;
+- (void)update;
 
 @end