test: add tests for AABB collision and rigid-body physics stepping

tests/testPhysics.cpp

@@ -0,0 +1,104 @@
+#include "testHarness.h"
+#include "vf/Physics.h"
+
+using namespace vf;
+
+namespace {
+
+World floorWorld() {
+    World world;
+    for (int x = 0; x < chunkSize; ++x)
+        for (int z = 0; z < chunkSize; ++z)
+            world.setBlock(x, 0, z, Block::Stone);
+    return world;
+}
+
+Player standingPlayer() {
+    Player player;
+    player.position = {8.0f, 5.0f, 8.0f};
+    return player;
+}
+
+} // namespace
+
+VF_TEST(physicsPlayerFallsAndLandsOnFloor) {
+    World world = floorWorld();
+    Player player = standingPlayer();
+    PhysicsConfig config;
+    MoveInput input;
+
+    for (int i = 0; i < 300; ++i) stepPlayer(world, player, input, config, 1.0f / 60.0f);
+
+    CHECK(player.onGround);
+    CHECK_NEAR(player.position.y, 1.0f, 0.02f);   // feet rest on top of the y=0 block
+    CHECK(!boxOverlapsSolid(world, playerBox(player)));
+}
+
+VF_TEST(physicsWallBlocksHorizontalMovement) {
+    World world = floorWorld();
+    for (int y = 1; y <= 3; ++y)
+        for (int z = 0; z < chunkSize; ++z)
+            world.setBlock(10, y, z, Block::Stone);
+
+    Player player = standingPlayer();
+    PhysicsConfig config;
+    MoveInput input;
+    input.strafe = 1.0f;   // yaw 0 -> pushes toward +x
+
+    for (int i = 0; i < 300; ++i) stepPlayer(world, player, input, config, 1.0f / 60.0f);
+
+    CHECK(player.position.x + player.width * 0.5f <= 10.0f + 1e-3f);
+    CHECK(!boxOverlapsSolid(world, playerBox(player)));
+}
+
+VF_TEST(physicsFlyModeIgnoresGravity) {
+    World world;   // empty, nothing to stand on
+    Player player;
+    player.position = {0.0f, 20.0f, 0.0f};
+    player.flying = true;
+    PhysicsConfig config;
+    MoveInput input;
+
+    for (int i = 0; i < 120; ++i) stepPlayer(world, player, input, config, 1.0f / 60.0f);
+
+    CHECK_NEAR(player.position.y, 20.0f, 1e-3f);   // hovers in place
+}
+
+VF_TEST(physicsFlyAscendsWithInput) {
+    World world;
+    Player player;
+    player.position = {0.0f, 20.0f, 0.0f};
+    player.flying = true;
+    PhysicsConfig config;
+    MoveInput input;
+    input.up = true;
+
+    stepPlayer(world, player, input, config, 1.0f / 60.0f);
+    CHECK(player.position.y > 20.0f);
+}
+
+VF_TEST(physicsJumpLeavesGround) {
+    World world = floorWorld();
+    Player player = standingPlayer();
+    PhysicsConfig config;
+    MoveInput settle;
+    for (int i = 0; i < 300; ++i) stepPlayer(world, player, settle, config, 1.0f / 60.0f);
+    CHECK(player.onGround);
+
+    float restY = player.position.y;
+    MoveInput jump;
+    jump.jump = true;
+    stepPlayer(world, player, jump, config, 1.0f / 60.0f);
+    CHECK(!player.onGround);
+    CHECK(player.position.y > restY);
+}
+
+VF_TEST(physicsCannotSpawnOverlappingResolvesOnStep) {
+    World world = floorWorld();
+    Player player = standingPlayer();
+    PhysicsConfig config;
+    MoveInput input;
+    for (int i = 0; i < 300; ++i) stepPlayer(world, player, input, config, 1.0f / 60.0f);
+    CHECK(!world.solidAt(static_cast<int>(player.position.x),
+                         static_cast<int>(player.position.y), 8));
+}