3d-tiles-renderer
Version:
https://github.com/AnalyticalGraphicsInc/3d-tiles/tree/master/specification
476 lines (297 loc) • 12.5 kB
JavaScript
import { LOADED, FAILED } from '../constants.js';
const viewErrorTarget = {
inView: false,
error: Infinity,
distanceFromCamera: Infinity,
};
// flag guiding the behavior of the traversal to load the siblings at the root of the
// tileset or not. The spec seems to indicate "true" when using REPLACE define but
// Cesium's behavior is "false".
// See CesiumGS/3d-tiles#776
const LOAD_ROOT_SIBLINGS = true;
function isDownloadFinished( value ) {
return value === LOADED || value === FAILED;
}
// Checks whether this tile was last used on the given frame.
function isUsedThisFrame( tile, frameCount ) {
return tile.__lastFrameVisited === frameCount && tile.__used;
}
function areChildrenProcessed( tile ) {
return tile.__childrenProcessed === tile.children.length;
}
function canUnconditionallyRefine( tile ) {
return tile.__hasUnrenderableContent || ( tile.parent && tile.parent.geometricError < tile.geometricError );
}
// Resets the frame information for the given tile
function resetFrameState( tile, renderer ) {
if ( tile.__lastFrameVisited !== renderer.frameCount ) {
tile.__lastFrameVisited = renderer.frameCount;
tile.__used = false;
tile.__inFrustum = false;
tile.__isLeaf = false;
tile.__visible = false;
tile.__active = false;
tile.__error = Infinity;
tile.__distanceFromCamera = Infinity;
tile.__allChildrenReady = false;
// update tile frustum and error state
renderer.calculateTileViewError( tile, viewErrorTarget );
tile.__inFrustum = viewErrorTarget.inView;
tile.__error = viewErrorTarget.error;
tile.__distanceFromCamera = viewErrorTarget.distanceFromCamera;
}
}
// Recursively mark tiles used down to the next layer, skipping external tilesets
function recursivelyMarkUsed( tile, renderer, cacheOnly = false ) {
renderer.ensureChildrenArePreprocessed( tile );
resetFrameState( tile, renderer );
markUsed( tile, renderer, cacheOnly );
// don't traverse if the children have not been processed, yet but tileset content
// should be considered to be "replaced" by the loaded children so await that here.
if ( canUnconditionallyRefine( tile ) && areChildrenProcessed( tile ) ) {
const children = tile.children;
for ( let i = 0, l = children.length; i < l; i ++ ) {
recursivelyMarkUsed( children[ i ], renderer, cacheOnly );
}
}
}
// Recursively traverses to the next tiles with unloaded renderable content to load them
function recursivelyLoadNextRenderableTiles( tile, renderer ) {
renderer.ensureChildrenArePreprocessed( tile );
// exit the recursion if the tile hasn't been used this frame
if ( isUsedThisFrame( tile, renderer.frameCount ) ) {
// queue this tile to download content
if ( tile.__hasContent ) {
renderer.queueTileForDownload( tile );
}
if ( areChildrenProcessed( tile ) ) {
// queue any used child tiles
const children = tile.children;
for ( let i = 0, l = children.length; i < l; i ++ ) {
recursivelyLoadNextRenderableTiles( children[ i ], renderer );
}
}
}
}
// Mark a tile as being used by current view
function markUsed( tile, renderer, cacheOnly = false ) {
if ( tile.__used ) {
return;
}
if ( ! cacheOnly ) {
tile.__used = true;
renderer.stats.used ++;
}
renderer.markTileUsed( tile );
if ( tile.__inFrustum === true ) {
renderer.stats.inFrustum ++;
}
}
// Returns whether the tile can be traversed to the next layer of children by checking the tile metrics
function canTraverse( tile, renderer ) {
// If we've met the error requirements then don't load further - if an external tileset is encountered,
// though, then continue to refine.
if ( tile.__error <= renderer.errorTarget && ! canUnconditionallyRefine( tile ) ) {
return false;
}
// Early out if we've reached the maximum allowed depth.
if ( renderer.maxDepth > 0 && tile.__depth + 1 >= renderer.maxDepth ) {
return false;
}
// Early out if the children haven't been processed, yet
if ( ! areChildrenProcessed( tile ) ) {
return false;
}
return true;
}
// Determine which tiles are used by the renderer given the current camera configuration
export function markUsedTiles( tile, renderer ) {
// determine frustum set is run first so we can ensure the preprocessing of all the necessary
// child tiles has happened here.
renderer.ensureChildrenArePreprocessed( tile );
resetFrameState( tile, renderer );
if ( ! tile.__inFrustum ) {
return;
}
if ( ! canTraverse( tile, renderer ) ) {
markUsed( tile, renderer );
return;
}
// Traverse children and see if any children are in view.
let anyChildrenUsed = false;
let anyChildrenInFrustum = false;
const children = tile.children;
for ( let i = 0, l = children.length; i < l; i ++ ) {
const c = children[ i ];
markUsedTiles( c, renderer );
anyChildrenUsed = anyChildrenUsed || isUsedThisFrame( c, renderer.frameCount );
anyChildrenInFrustum = anyChildrenInFrustum || c.__inFrustum;
}
// If none of the children are visible in the frustum then there should be no reason to display this tile. We still mark
// this tile and all children as "used" only in the cache (but not loaded) so they are not disposed, causing an oscillation
// / flicker in the content.
if ( tile.refine === 'REPLACE' && ! anyChildrenInFrustum && children.length !== 0 ) {
tile.__inFrustum = false;
for ( let i = 0, l = children.length; i < l; i ++ ) {
recursivelyMarkUsed( children[ i ], renderer, true );
}
return;
}
// wait until after the above condition to mark the traversed tile as used or not
markUsed( tile, renderer );
// If this is a tile that needs children loaded to refine then recursively load child
// tiles until error is met
if ( tile.refine === 'REPLACE' && ( anyChildrenUsed && tile.__depth !== 0 || LOAD_ROOT_SIBLINGS ) ) {
for ( let i = 0, l = children.length; i < l; i ++ ) {
recursivelyMarkUsed( children[ i ], renderer );
}
}
}
// Traverse and mark the tiles that are at the leaf nodes of the "used" tree.
export function markUsedSetLeaves( tile, renderer ) {
const frameCount = renderer.frameCount;
if ( ! isUsedThisFrame( tile, frameCount ) ) {
return;
}
// This tile is a leaf if none of the children had been used.
const children = tile.children;
let anyChildrenUsed = false;
for ( let i = 0, l = children.length; i < l; i ++ ) {
const c = children[ i ];
anyChildrenUsed = anyChildrenUsed || isUsedThisFrame( c, frameCount );
}
if ( ! anyChildrenUsed ) {
tile.__isLeaf = true;
} else {
let allChildrenReady = true;
for ( let i = 0, l = children.length; i < l; i ++ ) {
const c = children[ i ];
markUsedSetLeaves( c, renderer );
if ( isUsedThisFrame( c, frameCount ) ) {
// Compute whether this child is _allowed_ to display by checking the geometric error relative to the parent tile to avoid holes.
// If the child's geometric error is less than or equal to the parent's (or it has unrenderable content), we should NOT display the child to avoid holes.
// Only display the child if its geometric error is greater than the parent's and it has renderable content.
// Note that this behavior is undocumented in the 3d tiles specification and tilesets designed to take advantage of it may not work as expected
// in other rendering systems.
// See issue NASA-AMMOS/3DTilesRendererJS#1304
const childCanDisplay = ! canUnconditionallyRefine( c );
// Consider a child to be ready to be displayed if
// - the children's children have been loaded
// - the tile content has loaded
// - the tile is completely empty - ie has no children and no content
// - the child tileset has tried to load but failed
let isChildReady =
! c.__hasContent ||
( c.__hasRenderableContent && isDownloadFinished( c.__loadingState ) ) ||
( c.__hasUnrenderableContent && c.__loadingState === FAILED );
// Consider this child ready if it can be displayed and is ready for display or all of it's children ready to be displayed
isChildReady = ( childCanDisplay && isChildReady ) || c.__allChildrenReady;
allChildrenReady = allChildrenReady && isChildReady;
}
}
tile.__allChildrenReady = allChildrenReady;
}
}
// TODO: revisit implementation
// Skip past tiles we consider unrenderable because they are outside the error threshold.
export function markVisibleTiles( tile, renderer ) {
const stats = renderer.stats;
if ( ! isUsedThisFrame( tile, renderer.frameCount ) ) {
return;
}
// Request the tile contents or mark it as visible if we've found a leaf.
if ( tile.__isLeaf ) {
if ( tile.__loadingState === LOADED ) {
if ( tile.__inFrustum ) {
tile.__visible = true;
stats.visible ++;
}
tile.__active = true;
stats.active ++;
} else if ( tile.__hasContent ) {
renderer.queueTileForDownload( tile );
}
return;
}
const children = tile.children;
const hasContent = tile.__hasContent;
const loadedContent = isDownloadFinished( tile.__loadingState ) && hasContent;
const errorRequirement = ( renderer.errorTarget + 1 ) * renderer.errorThreshold;
const meetsSSE = tile.__error <= errorRequirement;
const isAdditiveRefine = tile.refine === 'ADD';
// TODO: the "meetsSSE" field can be removed when the "errorThreshold" field has been removed
// Don't wait for all children tiles to load if this tileset has empty tiles at the root in order
// to match Cesium's behavior
const allChildrenReady = tile.__allChildrenReady || ( tile.__depth === 0 && ! LOAD_ROOT_SIBLINGS );
// If we've met the SSE requirements and we can load content then fire a fetch.
if ( hasContent && ( meetsSSE || isAdditiveRefine ) ) {
renderer.queueTileForDownload( tile );
}
// By this time only tiles that meet the screen space error requirements will be traversed. Only mark this
// as visible if it's been loaded and not all children have loaded yet or it's an additive tile, meaning it needs
// to display in addition to the children.
// Skip the tile entirely if there's no content to load
if ( meetsSSE && loadedContent && ! allChildrenReady || loadedContent && isAdditiveRefine ) {
if ( tile.__inFrustum ) {
tile.__visible = true;
stats.visible ++;
}
tile.__active = true;
stats.active ++;
}
// If we're additive then don't stop the traversal here because it doesn't matter whether the children load in
// at the same rate.
if ( ! isAdditiveRefine && meetsSSE && ! allChildrenReady ) {
// load the child content if we've found that we've been loaded so we can move down to the next tile
// layer when the data has loaded.
for ( let i = 0, l = children.length; i < l; i ++ ) {
const c = children[ i ];
if ( isUsedThisFrame( c, renderer.frameCount ) ) {
recursivelyLoadNextRenderableTiles( c, renderer );
}
}
} else {
for ( let i = 0, l = children.length; i < l; i ++ ) {
markVisibleTiles( children[ i ], renderer );
}
}
}
// Final traverse to toggle tile visibility.
export function toggleTiles( tile, renderer ) {
const isUsed = isUsedThisFrame( tile, renderer.frameCount );
if ( isUsed || tile.__usedLastFrame ) {
let setActive = false;
let setVisible = false;
if ( isUsed ) {
// enable visibility if active due to shadows
setActive = tile.__active;
if ( renderer.displayActiveTiles ) {
setVisible = tile.__active || tile.__visible;
} else {
setVisible = tile.__visible;
}
} else {
// if the tile was used last frame but not this one then there's potential for the tile
// to not have been visited during the traversal, meaning it hasn't been reset and has
// stale values. This ensures the values are not stale.
resetFrameState( tile, renderer );
}
// If the active or visible state changed then call the functions.
if ( tile.__hasRenderableContent && tile.__loadingState === LOADED ) {
if ( tile.__wasSetActive !== setActive ) {
renderer.invokeOnePlugin( plugin => plugin.setTileActive && plugin.setTileActive( tile, setActive ) );
}
if ( tile.__wasSetVisible !== setVisible ) {
renderer.invokeOnePlugin( plugin => plugin.setTileVisible && plugin.setTileVisible( tile, setVisible ) );
}
}
tile.__wasSetActive = setActive;
tile.__wasSetVisible = setVisible;
tile.__usedLastFrame = isUsed;
const children = tile.children;
for ( let i = 0, l = children.length; i < l; i ++ ) {
const c = children[ i ];
toggleTiles( c, renderer );
}
}
}