line.span.arrayMask |= SPAN_INDEX;
if (ctx->Light.ShadeModel == GL_SMOOTH) {
compute_plane(line.x0, line.y0, line.x1, line.y1,
line.span.arrayMask |= SPAN_INDEX;
if (ctx->Light.ShadeModel == GL_SMOOTH) {
compute_plane(line.x0, line.y0, line.x1, line.y1,