feat: add spot light shadows with a tilled buffer

tests/destrum_tests.cpp

@@ -35,6 +35,8 @@
 #include <destrum/Graphics/Resources/PrimitiveMeshes.h>
 #include <destrum/Graphics/Managers/Renderer2D.h>
 #include <destrum/Graphics/Resources/Font.h>
+#include <glm/gtc/matrix_transform.hpp>
+#include <destrum/Graphics/Frustum.h>
 #include <destrum/Components/LightComponent.h>
 #include <destrum/Components/Physics/Rigidbody.h>
 #include <destrum/Graphics/Material.h>
@@ -511,6 +513,33 @@ namespace {
         SceneManager::GetInstance().Destroy();
     }
 
+    void testFrustumFromViewProj()
+    {
+        const auto lookingAlongPositiveZ = [](const glm::vec3& position, float range) {
+            const glm::mat4 view = glm::lookAt(position, position + glm::vec3{0.0f, 0.0f, 1.0f}, glm::vec3{0.0f, 1.0f, 0.0f});
+            return glm::perspectiveRH_ZO(glm::radians(60.0f), 1.0f, 0.1f, range) * view;
+        };
+
+        const glm::mat4 viewProj = lookingAlongPositiveZ(glm::vec3{0.0f}, 20.0f);
+        const Frustum frustum = edge::createFrustumFromViewProj(viewProj);
+
+        check(edge::isInFrustum(frustum, Sphere{{0.0f, 0.0f, 10.0f}, 0.5f}), "a sphere in front must be inside");
+        check(!edge::isInFrustum(frustum, Sphere{{0.0f, 0.0f, -5.0f}, 0.5f}), "a sphere behind must be outside");
+        check(!edge::isInFrustum(frustum, Sphere{{0.0f, 0.0f, 30.0f}, 0.5f}), "a sphere past the far plane must be outside");
+        check(!edge::isInFrustum(frustum, Sphere{{15.0f, 0.0f, 10.0f}, 0.5f}), "a sphere to the side must be outside");
+
+        const auto corners = edge::calculateFrustumCorners(viewProj);
+        const bool cornersOnNearAndFar = std::ranges::all_of(corners, [](const glm::vec3& corner) {
+            return std::abs(corner.z - 0.1f) < 0.001f || std::abs(corner.z - 20.0f) < 0.01f;
+        });
+        check(cornersOnNearAndFar, "frustum corners must lie on the near and far planes");
+
+        check(edge::frustumsOverlap(frustum, lookingAlongPositiveZ(glm::vec3{0.0f, 0.0f, 5.0f}, 10.0f)),
+              "a frustum in front of the camera must overlap");
+        check(!edge::frustumsOverlap(frustum, lookingAlongPositiveZ(glm::vec3{0.0f, 0.0f, -30.0f}, 10.0f)),
+              "a frustum entirely behind the camera must not overlap");
+    }
+
     void testRenderer2DShapes()
     {
         auto& r2d = Renderer2D::GetInstance();
@@ -1305,6 +1334,7 @@ int main()
     testPrimitiveBoxMesh();
     testColliderCenterOffset();
     testCapsuleColliderDebugLines();
+    testFrustumFromViewProj();
     testRenderer2DShapes();
     testFontAtlasAndLayout();
     std::cout << "destrum tests passed\n";