test_that("`oblicubesGrob()`", {
	skip_if_not_installed("grid")
	skip_if_not_installed("vdiffr")
	library("grid")
	library("vdiffr")

	expect_doppelganger("basic_op_angles", function() {
		angles <- c(135, 90, 45, 180, 45, 0, -135, -90, -45)
		scales <- c(0.5, 0.5, 0.5, 0.5, 0.0, 0.5, 0.5, 0.5, 0.5)
		mat <- matrix(c(1, 2, 1, 2, 3, 2, 1, 2, 1), nrow = 3, ncol = 3, byrow = TRUE)
		coords <- xyz_heightmap(mat, col = c("red", "yellow", "green"))
		vp_x <- rep(1:3 / 3 - 1 / 6, 3)
		vp_y <- rep(3:1 / 3 - 1 / 6, each = 3)

		for (i in 1:9) {
			pushViewport(viewport(x = vp_x[i], y = vp_y[i], width = 1 / 3, height = 1 / 3))
			grid.rect(gp = gpar(lty = "dashed"))
			grid.oblicubes(
				coords,
				width = 0.15,
				xo = 0.25,
				yo = 0.15,
				angle = angles[i],
				scale = scales[i],
				light = FALSE,
				gp = gpar(lwd = 4)
			)
			if (i != 5) {
				grid.text(paste("angle =", angles[i]), y = 0.92, gp = gpar(cex = 1.2))
			} else {
				grid.text(paste("scale = 0"), y = 0.92, gp = gpar(cex = 1.2))
			}
			popViewport()
		}
	})

	expect_doppelganger("ground_yz", function() {
		mat <- matrix(c(1, 2, 1, 2, 3, 2, 1, 2, 1), nrow = 3, ncol = 3, byrow = TRUE)
		coords <- xyz_heightmap(mat, ground = "xz")
		grid.oblicubes(coords, gp = gpar(lwd = 4, fill = "lightgreen"))
	})
	expect_doppelganger("ground_zy", function() {
		mat <- matrix(c(1, 2, 1, 2, 3, 2, 1, 2, 1), nrow = 3, ncol = 3, byrow = TRUE)
		coords <- xyz_heightmap(mat, ground = "zy")
		grid.oblicubes(coords, lwd = 4)
	})
	expect_doppelganger("null", function() {
		grid.oblicubes(data.frame(x = integer(0), y = integer(0), z = integer(0)))
	})
	expect_doppelganger("null2", function() {
		grid.oblicubes(x = integer(0), y = integer(0), z = integer(0))
	})
})