R68 Lightmap failure (+ fix)

[Fabrice3D]

using r68. In case of lightmap, if two sets of uvs are defined in json, uvs = [ [primary uv set], [ secondary uv set] ]. The engine either renders weird geometry or generates webgl errors.

The cause is found by faulty increase of face index.

for ( i = 0; i < nUvLayers; i ++ ) {  //loop over uv sets
     uvLayer = json.uvs[ i ];  //assign the json uv set data from json parser
    geometry.faceVertexUvs[ i ][ fi ] = []; //make array for indices lookup
        for ( j = 0; j < 3; j ++ ) { //loop over the 3 vertices (or 4 for quad case)
            uvIndex = faces[ offset ++ ]; //get faces index.

in a one face case, the last line becomes on first iteration, offset = 0,1,2, on second iteration offset becomes 3,4,5, while the secondary set should still point at 0,1,2.

fix:
add on top "parseModel" method:

var collectedIndices = [0,0,0,0];

the quad loop becomes:

if ( hasFaceVertexUv ) {

                    for ( i = 0; i < nUvLayers; i ++ ) {

                        uvLayer = json.uvs[ i ];

                        geometry.faceVertexUvs[ i ][ fi ] = [];
                        geometry.faceVertexUvs[ i ][ fi + 1 ] = []

                        for ( j = 0; j < 4; j ++ ) {

                            if(i == 0) collectedIndices[j] = offset++;

                            uvIndex = faces[ collectedIndices[j] ];

                            u = uvLayer[ uvIndex * 2 ];
                            v = uvLayer[ uvIndex * 2 + 1 ];

                            uv = new THREE.Vector2( u, v );

                            if ( j !== 2 ) geometry.faceVertexUvs[ i ][ fi ].push( uv );
                            if ( j !== 0 ) geometry.faceVertexUvs[ i ][ fi + 1 ].push( uv );

                        }

                    }

                }

the 3 vertices case becomes:

for ( i = 0; i < nUvLayers; i ++ ) {

                        uvLayer = json.uvs[ i ];

                        geometry.faceVertexUvs[i][ fi ] = [];

                        for ( j = 0; j < 3; j ++ ) {

                            if(i == 0) collectedIndices[j] = offset++;

                            uvIndex = faces[ collectedIndices[j] ];

                            u = uvLayer[ uvIndex * 2 ];
                            v = uvLayer[ uvIndex * 2 + 1 ];

                            uv = new THREE.Vector2( u, v );
                            geometry.faceVertexUvs[ i ][ fi ].push( uv );
                        }

                    }

Now the engine renders models using 2 sets of uv's with lightmap as expected.

[ringodotnl]

Thx Fab for posting this!;)

[mrdoob]

Where is this? JSONLoader?

[Fabrice3D]

Yes, in JSONLoader.prototype.parse function parseModel, line 119.

[Mugen87]

JSONLoader has been removed, see #15310.