public class Tessellation {
public static interface Callback {
void index(short index);
}
private final Callback callback;
private final GLUtessellator tessellator = GLU.gluNewTess();
private static interface Handler {
void index(short index);
}
private final class TriangleHandler implements Handler {
@Override
public void index(short index) {
callback.index(index);
}
}
private final TriangleHandler triangleHandler = new TriangleHandler();
private final class TriangleStripHandler implements Handler {
private boolean first;
private boolean second;
private short index1;
private short index2;
@Override
public void index(short index) {
if (!first) {
index1 = index;
first = true;
} else if (first && !second) {
index2 = index;
second = true;
} else {
callback.index(index1);
callback.index(index2);
callback.index(index);
index1 = index2;
index2 = index;
}
}
}
private final TriangleStripHandler triangleStripHandler = new TriangleStripHandler();
private final class TriangleFanHandler implements Handler {
private boolean first;
private boolean second;
private short firstIndex;
private short lastIndex;
@Override
public void index(short index) {
if (!first) {
firstIndex = index;
first = true;
} else if (first && !second) {
lastIndex = index;
second = true;
} else {
callback.index(firstIndex);
callback.index(lastIndex);
callback.index(index);
lastIndex = index;
}
}
}
private final TriangleFanHandler triangleFanHandler = new TriangleFanHandler();
{
final GLUtessellatorCallback callback =
new GLUtessellatorCallbackAdapter() {
private volatile Handler handler;
@Override
public void begin(int type) {
switch (type) {
case GL.GL_TRIANGLES:
handler = triangleHandler;
break;
case GL.GL_TRIANGLE_STRIP:
handler = triangleStripHandler;
break;
case GL.GL_TRIANGLE_FAN:
handler = triangleFanHandler;
break;
}
}
@Override
public void vertex(Object index) {
handler.index((short) index);
}
};
GLU.gluTessCallback(tessellator, GLU.GLU_TESS_BEGIN, callback);
GLU.gluTessCallback(tessellator, GLU.GLU_TESS_VERTEX, callback);
}
public Tessellation(float[] vertices, short[] indices, Callback callback) {
this.callback = callback;
GLU.gluBeginPolygon(tessellator);
for (short index : indices) {
double w = vertices[index * 4 + 3];
GLU.gluTessVertex(
tessellator,
new double[] {
vertices[index * 4] / w, vertices[index * 4 + 1] / w, vertices[index * 4 + 2] / w
},
0,
index);
}
GLU.gluEndPolygon(tessellator);
}
@Override
protected void finalize() {
GLU.gluDeleteTess(tessellator);
}
}
