func setupGeometry(gl *webgl.Context, program *js.Object) {
gl.BindBuffer(gl.ARRAY_BUFFER, gl.CreateBuffer())
gl.BufferData(gl.ARRAY_BUFFER, buildArray(), gl.STATIC_DRAW)
positionLocation := gl.GetAttribLocation(program, "a_position")
gl.EnableVertexAttribArray(positionLocation)
gl.VertexAttribPointer(positionLocation, 2, gl.FLOAT, false, 0, 0)
}
func (o *Obj) Read(reader io.Reader, gl *webgl.Context) error {
var group *ObjGroup
var materialName string
var positions []float32
var normals []float32
var texcoords []float32
var float2 [2]float32 = [2]float32{0, 0}
var float3 [3]float32 = [3]float32{0, 0, 0}
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
line := strings.TrimSpace(scanner.Text())
if line == "" || strings.HasPrefix(line, "#") {
// Blank line or comment, ignore it
continue
}
// Split line into fields on whitespace
fields := strings.Fields(line)
switch strings.ToLower(fields[0]) {
// Vertex position.
case "v":
if err := parseFloat3(fields[1:4], &float3); err != nil {
return err
}
positions = append(positions, float3[0], float3[1], float3[2])
// Vertex normal.
case "vn":
if err := parseFloat3(fields[1:4], &float3); err != nil {
return err
}
normals = append(normals, float3[0], float3[1], float3[2])
// Vertex texture coordinates.
case "vt":
if err := parseFloat2(fields[1:3], &float2); err != nil {
return err
}
texcoords = append(texcoords, float2[0], 1.0-float2[1])
// Face indices, specified in sets of "position/uv/normal".
case "f":
faces := fields[1:len(fields)]
if group == nil {
group = &ObjGroup{MaterialName: materialName}
o.Groups = append(o.Groups, group)
}
group.faces = append(group.faces, faces)
// New group, with a name.
case "g":
group = &ObjGroup{Name: fields[1], MaterialName: materialName}
o.Groups = append(o.Groups, group)
// Object name. The obj will only have one object statement.
case "o":
o.Name = fields[1]
// Material library. I'm not handling this for now. Instead, call
// SetMaterial() for each of the named materials.
// case "mtllib":
// Specifies the material for the current group (and any future groups
// that don't have their own usemtl statement).
case "usemtl":
materialName = fields[1]
if group != nil {
group.MaterialName = materialName
}
}
}
if err := scanner.Err(); err != nil {
return err
}
// Normalize the vertices. OBJ does two things that cause problems for
// modern renderers: it allows faces to be polygons, instead of only
// triangles; and it allows each face vertex to have a different index
// for each stream (position, normal, uv).
//
// This code creates triangle fans out of any faces that have more than
// three vertexes, and merges distinct groupings of pos/normal/uv into
// a single vertex stream.
var faceIndices [3]uint16 = [3]uint16{0, 0, 0}
o.tupleIndex = 0
for _, g := range o.Groups {
for _, f := range g.faces {
for i := 1; i < len(f)-1; i++ {
var err error
if faceIndices[0], err = o.mergeTuple(f[i], positions, normals, texcoords); err != nil {
return err
}
if faceIndices[1], err = o.mergeTuple(f[0], positions, normals, texcoords); err != nil {
return err
}
if faceIndices[2], err = o.mergeTuple(f[i+1], positions, normals, texcoords); err != nil {
return err
}
g.indices = append(g.indices, faceIndices[0], faceIndices[1], faceIndices[2])
}
}
g.IndexBuffer = gl.CreateBuffer()
gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, g.IndexBuffer)
gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, g.indices, gl.STATIC_DRAW)
g.NumIndices = len(g.indices)
}
o.VertexBuffer = gl.CreateBuffer()
gl.BindBuffer(gl.ARRAY_BUFFER, o.VertexBuffer)
gl.BufferData(gl.ARRAY_BUFFER, o.vertices, gl.STATIC_DRAW)
return nil
}