I'm writing an android app using openGL ES. I followed some online tutorials and managed to load up a textured cube using hard-coded vertices/indices/texture coordinates
As a next step I wrote a parser for wavefront .obj files. I made a mock file using the vertices etc from the tutorial, which loads fine.
However, when I use a file made using a 3d modelling package, all the textures get messed up
Below is how I'm currently getting the texture coordinates:
First I load all the texture coordinates, the vt's into a big vector
Next I find the first two texture coordinates for each f triangle (so f 1/2/3 2/5/2 3/4/1 means I take the 2nd and 5th texture coordinates. Since .obj starts counting from 1 not 0, I have to -1 from the position and then multiply the position by 2 for the x coord position and do the same but +1 for the y coord position in my vt array)
I take those texture coordinates that I just found and add them to another vector.
Once I've gone through all the vertices. I turn the vector into a FloatBuffer, passing that to glTexCoordPointer in my draw method
Here is the code for parsing the file:
private void openObjFile(String filename, Context context, GL10 gl){
Vector<String> lines = openFile(filename, context); // opens the file
Vector<String[]> tokens = new Vector<String[]>();
Vector<Float> vertices = new Vector<Float>();
Vector<Float> textureCoordinates = new Vector<Float>();
Vector<Float> vertexNormals = new Vector<Float>();
// tokenise
for(int i = 0;i<lines.size();i++){
String line = lines.get(i);
tokens.add(line.split(" "));
}
for(int j = 0;j<tokens.size();j++){
String[] linetokens = tokens.get(j);
// get rid of comments
//if(linetokens[0].equalsIgnoreCase("#")){
//tokens.remove(j);
//}
// get texture from .mtl file
if(linetokens[0].equalsIgnoreCase("mtllib")){
parseMaterials(linetokens[1],context, gl);
}
// vertices
if(linetokens[0].equalsIgnoreCase("v")){
vertices.add(Float.valueOf(linetokens[1]));
vertices.add(Float.valueOf(linetokens[2]));
vertices.add(Float.valueOf(linetokens[3]));
}
// texture coordinates
if(linetokens[0].equalsIgnoreCase("vt")){
textureCoordinates.add(Float.valueOf(linetokens[1]));
textureCoordinates.add(Float.valueOf(linetokens[2]));
}
// vertex normals
if(linetokens[0].equalsIgnoreCase("vn")){
vertexNormals.add(Float.valueOf(linetokens[1]));
vertexNormals.add(Float.valueOf(linetokens[2]));
vertexNormals.add(Float.valueOf(linetokens[3]));
}
}
// vertices
this.vertices = GraphicsUtil.getFloatBuffer(vertices);
Mesh mesh = null;
Vector<Short> indices = null;
Vector<Float> textureCoordinatesMesh = null;
Vector<Float> vertexNormalsMesh = null;
for(int j = 0;j<tokens.size();j++){
String[] linetokens = tokens.get(j);
if(linetokens[0].equalsIgnoreCase("g")){
if(mesh!=null){
mesh.setIndices(GraphicsUtil.getShortBuffer(indices));
mesh.setNumindices(indices.size());
mesh.setNormals(GraphicsUtil.getFloatBuffer(vertexNormalsMesh));
mesh.setTextureCoordinates(GraphicsUtil.getFloatBuffer(textureCoordinatesMesh));
meshes.add(mesh);
}
mesh = new Mesh();
indices = new Vector<Short>();
textureCoordinatesMesh = new Vector<Float>();
vertexNormalsMesh = new Vector<Float>();
} else if(linetokens[0].equalsIgnoreCase("usemtl")){
String material_name = linetokens[1];
for(int mn = 0;mn<materials.size();mn++){
if(materials.get(mn).getName().equalsIgnoreCase(material_name)){
mesh.setTextureID(materials.get(mn).getTextureID());
mn = materials.size();
}
}
} else if(linetokens[0].equalsIgnoreCase("f")){
for(int v = 1;v<linetokens.length;v++){
String[] vvtvn = linetokens[v].split("/");
short index = Short.parseShort(vvtvn[0]);
index -= 1;
indices.add(index);
if(v!=3){
int texturePosition = (Integer.parseInt(vvtvn[1]) - 1) * 2;
float xcoord = (textureCoordinates.get(texturePosition));
float ycoord = (textureCoordinates.get(texturePosition+1));
// normalise
if(xcoord>1 || ycoord>1){
xcoord = xcoord / Math.max(xcoord, ycoord);
ycoord = ycoord / Math.max(xcoord, ycoord);
}
textureCoordinatesMesh.add(xcoord);
textureCoordinatesMesh.add(ycoord);
}
int normalPosition = (Integer.parseInt(vvtvn[2]) - 1) *3;
vertexNormalsMesh.add(vertexNormals.get(normalPosition));
vertexNormalsMesh.add(vertexNormals.get(normalPosition)+1);
vertexNormalsMesh.add(vertexNormals.get(normalPosition)+2);
}
}
}
if(mesh!=null){
mesh.setIndices(GraphicsUtil.getShortBuffer(indices));
mesh.setNumindices(indices.size());
mesh.setNormals(GraphicsUtil.getFloatBuffer(vertexNormalsMesh));
mesh.setTextureCoordinates(GraphicsUtil.getFloatBuffer(textureCoordinatesMesh));
meshes.add(mesh);
}// Adding the final mesh
}
And here is the code for drawing:
public void draw(GL10 gl){
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
// Counter-clockwise winding.
gl.glFrontFace(GL10.GL_CCW);
gl.glEnable(GL10.GL_CULL_FACE);
gl.glCullFace(GL10.GL_BACK);
// Pass the vertex buffer in
gl.glVertexPointer(3, GL10.GL_FLOAT, 0,
vertices);
for(int i=0;i<meshes.size();i++){
meshes.get(i).draw(gl);
}
// Disable the buffers
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
}
public void draw(GL10 gl){
if(textureID>=0){
// Enable Textures
gl.glEnable(GL10.GL_TEXTURE_2D);
// Get specific texture.
gl.glBindTexture(GL10.GL_TEXTURE_2D, textureID);
// Use UV coordinates.
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
// Pass in texture coordinates
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureCoordinates);
}
// Pass in texture normals
gl.glNormalPointer(GL10.GL_FLOAT, 0, normals);
gl.glEnableClientState(GL10.GL_NORMAL_ARRAY);
gl.glDrawElements(GL10.GL_TRIANGLES, numindices,GL10.GL_UNSIGNED_SHORT, indices);
if(textureID>=0){
// Disable buffers
gl.glDisableClientState(GL10.GL_NORMAL_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
}
}
I'd really appreciate any help with this. It is frustrating to be not-quite able to load up the model from file and I'm really not sure what I'm doing wrong or missing here
