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#include <math/vec3.h>
#include <math/float.h>
#include "test.h"
#include <stdio.h>
static const float eps = 1e-7;
static inline void print_vec3(vec3 v) {
printf("{ %f, %f, %f }\n", v.x, v.y, v.z);
}
/// Slerp between two vectors forming an acute angle.
TEST_CASE(vec3_slerp_acute_angle) {
const R angle1 = 0;
const R angle2 = PI / 4;
const R t = 0.5;
const vec3 a = vec3_make(cos(angle1), sin(angle1), 0);
const vec3 b = vec3_make(cos(angle2), sin(angle2), 0);
const vec3 result = vec3_slerp(a, b, t);
const R angle3 = lerp(angle1, angle2, t);
const vec3 expected = vec3_make(cos(angle3), sin(angle3), 0.0);
TEST_TRUE(vec3_eq(result, expected, eps));
}
/// Slerp between two vectors forming an obtuse angle (negative dot product).
///
/// The interpolation must follow the shortest path between both vectors.
TEST_CASE(vec3_slerp_obtuse_angle) {
const R angle1 = 0;
const R angle2 = 3 * PI / 4;
const R t = 0.5;
const vec3 a = vec3_make(cos(angle1), sin(angle1), 0);
const vec3 b = vec3_make(cos(angle2), sin(angle2), 0);
const vec3 result = vec3_slerp(a, b, t);
const R angle3 = lerp(angle1, angle2, t);
const vec3 expected = vec3_make(cos(angle3), sin(angle3), 0.0);
TEST_TRUE(vec3_eq(result, expected, eps));
}
/// Slerp between two vectors forming a reflex angle.
///
/// The interpolation must follow the shortest path between both vectors.
TEST_CASE(vec3_slerp_reflex_angle) {
const R angle1 = 0;
const R angle2 = 5 * PI / 4;
const R t = 0.5;
const vec3 a = vec3_make(cos(angle1), sin(angle1), 0);
const vec3 b = vec3_make(cos(angle2), sin(angle2), 0);
const vec3 result = vec3_slerp(a, b, t);
// slerp goes from a to b following the shortest path, which is down from a
// towards b. The resulting angle is therefore +PI of the angle we get from
// lerping the two input angles.
const R angle3 = lerp(angle1, angle2, t) + PI;
const vec3 expected = vec3_make(cos(angle3), sin(angle3), 0.0);
TEST_TRUE(vec3_eq(result, expected, 1e-5));
}
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