b400958c3e
Co-Authored-By: selune <0xlillith@users.noreply.github.com> Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
92 lines
3.6 KiB
Rust
92 lines
3.6 KiB
Rust
use super::*;
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fn close(a: f64, b: f64) {
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assert!((a - b).abs() <= 1e-12 * b.abs().max(1.0), "{a} != {b}");
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}
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#[test]
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fn magnification_zero_integer_and_fractional_minification() {
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for (footprint, expected) in [(0., 0.), (0.25, 0.), (1., 0.), (2., 1.), (2_f64.sqrt(), 0.5), (8., 3.)] {
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let result = select_isotropic_lod([256, 256], [footprint / 256., 0.], [0., footprint / 256.]).unwrap();
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close(result.footprint_texels, footprint);
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close(result.lod, expected);
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assert_eq!(result.max_level, 8);
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}
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}
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#[test]
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fn rectangular_textures_scale_each_uv_axis_separately() {
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let result = select_isotropic_lod([512, 128], [1. / 512., 0.], [0., 1. / 128.]).unwrap();
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close(result.footprint_texels, 1.);
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close(result.lod, 0.);
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let result = select_isotropic_lod([512, 128], [0., 4. / 128.], [2. / 512., 0.]).unwrap();
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close(result.footprint_texels, 4.);
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close(result.lod, 2.);
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}
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#[test]
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fn supplied_derivatives_follow_the_actual_supersampling_grid() {
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// A final-image pixel covers4 texels. On a2x4 shading grid its per-step
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// footprints are2 and1; final downsampling remains a separate operation.
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let dx = [4. / 256., 0.];
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let dy = [0., 4. / 256.];
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let coarse = select_isotropic_lod([256, 256], dx, dy).unwrap();
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let fine = select_isotropic_lod([256, 256], dx.map(|v| v / 2.), dy.map(|v| v / 4.)).unwrap();
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close(coarse.lod, 2.);
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close(fine.footprint_texels, 2.);
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close(fine.lod, 1.);
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}
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#[test]
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fn shear_uses_singular_value_rather_than_smaller_max_column_norm() {
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// J columns both [2,0]: max column length2, true largest singular value sqrt8.
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let result = select_isotropic_lod([256, 256], [2. / 256., 0.], [2. / 256., 0.]).unwrap();
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close(result.footprint_texels, 8_f64.sqrt());
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close(result.lod, 1.5);
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}
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#[test]
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fn rotation_sign_and_screen_axis_swap_preserve_the_footprint() {
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let angle = 0.37_f64;
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let (s, c) = angle.sin_cos();
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// Rotated texel-space axes with singular values4 and2, rectangular base.
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let x = [4. * c / 512., 4. * s / 128.];
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let y = [-2. * s / 512., 2. * c / 128.];
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for (dx, dy) in [(x, y), (y, x), (x.map(|v| -v), y), (x, y.map(|v| -v))] {
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let result = select_isotropic_lod([512, 128], dx, dy).unwrap();
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close(result.footprint_texels, 4.);
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close(result.lod, 2.);
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}
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}
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#[test]
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fn full_chain_saturation_is_explicit_for_odd_single_axis_and_single_texel_images() {
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for (dimensions, last) in [([5, 3], 2), ([7, 1], 2), ([1, 7], 2), ([1, 1], 0), ([2048, 2048], 11)] {
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let result = select_isotropic_lod(dimensions, [MAX_UV_GRADIENT; 2], [MAX_UV_GRADIENT; 2]).unwrap();
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assert_eq!(result.max_level, last);
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close(result.lod, f64::from(last));
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assert!(result.footprint_texels.is_finite());
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}
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}
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#[test]
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fn zero_and_tiny_gradients_are_finite() {
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for value in [0., -0., f64::MIN_POSITIVE, f64::from_bits(1)] {
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let result = select_isotropic_lod([2048, 2048], [value; 2], [value; 2]).unwrap();
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assert!(result.footprint_texels.is_finite());
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close(result.lod, 0.);
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}
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}
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#[test]
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fn hostile_dimensions_and_each_gradient_component_refuse() {
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for dimensions in [[0, 1], [1, 0], [MAX_TEXTURE_EDGE + 1, 1], [u32::MAX; 2]] {
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assert_eq!(select_isotropic_lod(dimensions, [0.; 2], [0.; 2]), Err(LodError::Dimensions));
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}
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for value in [f64::NAN, f64::INFINITY, f64::NEG_INFINITY, f64::MAX, MAX_UV_GRADIENT + 1., -MAX_UV_GRADIENT - 1.] {
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for (x, y) in [([value, 0.], [0., 0.]), ([0., value], [0., 0.]), ([0., 0.], [value, 0.]), ([0., 0.], [0., value])] {
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assert_eq!(select_isotropic_lod([2, 2], x, y), Err(LodError::Gradients));
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}
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}
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}
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