Edit your ShapeRenderer.java class replacing polygon() method with the following code:
public void polygon(float[] vertices, int offset, int count) {
if (currType != ShapeType.Filled && currType != ShapeType.Line)
throw new GdxRuntimeException(
"Must call begin(ShapeType.Filled) or begin(ShapeType.Line)");
if (count < 6)
throw new IllegalArgumentException(
"Polygons must contain at least 3 points.");
if (count % 2 != 0)
throw new IllegalArgumentException(
"Polygons must have an even number of vertices.");
checkDirty();
checkFlush(count);
final float firstX = vertices[0];
final float firstY = vertices[1];
if (currType == ShapeType.Line) {
for (int i = offset, n = offset + count; i < n; i += 2) {
final float x1 = vertices[i];
final float y1 = vertices[i + 1];
final float x2;
final float y2;
if (i + 2 >= count) {
x2 = firstX;
y2 = firstY;
} else {
x2 = vertices[i + 2];
y2 = vertices[i + 3];
}
renderer.color(color);
renderer.vertex(x1, y1, 0);
renderer.color(color);
renderer.vertex(x2, y2, 0);
}
} else {
for (int i = offset, n = offset + count; i < n; i += 4) {
final float x1 = vertices[i];
final float y1 = vertices[i + 1];
if (i + 2 >= count) {
break;
}
final float x2 = vertices[i + 2];
final float y2 = vertices[i + 3];
final float x3;
final float y3;
if (i + 4 >= count) {
x3 = firstX;
y3 = firstY;
} else {
x3 = vertices[i + 4];
y3 = vertices[i + 5];
}
renderer.color(color);
renderer.vertex(x1, y1, 0);
renderer.color(color);
renderer.vertex(x2, y2, 0);
renderer.color(color);
renderer.vertex(x3, y3, 0);
}
}
}
Usage:
gdx_shape_renderer.begin(ShapeType.Filled);
gdx_shape_renderer.setColor(fill_r, fill_g, fill_b, fill_a);
gdx_shape_renderer.polygon(vertices);
gdx_shape_renderer.end();
gdx_shape_renderer.begin(ShapeType.Line);
gdx_shape_renderer.setColor(border_r, border_g, border_b, border_a);
gdx_shape_renderer.polygon(vertices);
gdx_shape_renderer.end();