Problem with vertexBuffer

Help & Support
1

Hello.

I’m trying to get vertexes’ position from vertexBuffer and render lines between em.

Get vertexes:


    this.points = [];
    var buffer = this.entity.model.model.meshInstances[0].mesh.vertexBuffer;
    var iterator = new pc.VertexIterator(buffer);
    
    for(i = 0; i < buffer.getNumVertices(); i++) {
       
        var posSem = iterator.element[pc.SEMANTIC_POSITION];
        
        posX = posSem.array[posSem.index];
        posY = posSem.array[posSem.index + 1];
        posZ = posSem.array[posSem.index + 2];
       
        var pos = new pc.Vec3(posX, posY, posZ);
        this.points.push(pos);        
        iterator.next();
        
    }
    
    iterator.end();

Render lines:

for (i = 0; i <  this.points.length-1; i++) {   
        var pointA =  this.points[i];
        
        for (j = i+1; j <  this.points.length; j++) {
            var pointB =  this.points[j];
            
            var dx = pointA.x - pointB.x;
            var dy = pointA.y - pointB.y;
            var dz = pointA.z - pointB.z;
            
            var dist = Math.sqrt(dx*dx + dy*dy + dz*dz);
            
            if (dist < 15) {
                this.app.renderLine(pointA, pointB, new pc.Color(1,1,1));
            }
        }
        
    }

And the problems is that my vertexes’ positions are not correct and much more than actual geometry.

image.png1386×915 67.6 KB

I think I probably have to multiply my pos vector by viewProject matrix, but i’m not quite sure how to do that.

2

Before adding a point to your points array, multiply it by the model matrix, that’ll apply translation/rotation/scaling to your vertices :slight_smile:

// get matrix beforehand, don't need to call it for every vertex
var matrix = this.entity.model.meshInstances[0].node.getWorldTransform(); 

// in your loop, multiply the pos
matrix.transformPoint(pos, pos);
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