physics and rendering fixes

test/rpg/physics/test_physicsworld.c

@@ -224,16 +224,91 @@ static void test_physicsWorldStepMultiColumnFootprint(void **state) {
   assert_int_equal(memoryGetAllocatedCount(), 0);
 }
 
-static void test_physicsWorldStepRampTreatedAsFlatGround(void **state) {
+static void test_physicsWorldStepClimbsRampGoingUp(void **state) {
   testMapReset();
   testMapSetTile(0, 0, 0, TILE_SHAPE_GROUND);
   testMapSetTile(1, 0, 0, TILE_SHAPE_RAMP_EAST);
+  for(worldunit_t x = 2; x < 6; x++) {
+    testMapSetTile(x, 0, 1, TILE_SHAPE_GROUND);
+  }
+
+  physicsworld_t world;
+  physicsWorldInit(&world, 20.0f, 40.0f);
+
+  physicsbody_t body;
+  const vec3 position = { 0.0f, 0.0f, 0.0f };
+  const vec3 extents = { 1.0f, 1.0f, 1.0f };
+  physicsBodyInit(&body, position, extents);
+  body.velocity[0] = 1.0f;
+
+  for(uint32_t i = 0; i < 400; i++) {
+    physicsWorldStep(&world, &body, DUSK_TIME_STEP, NULL, 0);
+
+    // Ground height is driven by the body's center (not its corner
+    // position), so a 1-wide body barely touching a taller neighbouring
+    // column isn't yanked onto that column's full height - see
+    // physicsWorldResolveAxisZ. While the center is over the ramp tile,
+    // height should track how far across it smoothly, not snap flat.
+    const float_t centerX = body.position[0] + 0.5f;
+    if(centerX >= 1.0f && centerX < 2.0f) {
+      const float_t expected = centerX - 1.0f;
+      assert_float_equal(body.position[2], expected, 0.005f);
+    }
+  }
+
+  // Fully across, resting on the elevated ground one layer up.
+  assert_float_equal(body.position[0], 5.0f, 0.001f);
+  assert_float_equal(body.position[2], 1.0f, 0.005f);
+  assert_true(body.grounded);
+
+  assert_int_equal(memoryGetAllocatedCount(), 0);
+}
+
+static void test_physicsWorldStepDescendsRampGoingDown(void **state) {
+  testMapReset();
+  testMapSetTile(0, 0, 1, TILE_SHAPE_GROUND);
+  testMapSetTile(1, 0, 0, TILE_SHAPE_RAMP_WEST);
   for(worldunit_t x = 2; x < 6; x++) {
     testMapSetTile(x, 0, 0, TILE_SHAPE_GROUND);
   }
 
   physicsworld_t world;
-  physicsWorldInit(&world, 0.0f, 40.0f);
+  physicsWorldInit(&world, 20.0f, 40.0f);
+
+  physicsbody_t body;
+  const vec3 position = { 0.0f, 0.0f, 1.0f };
+  const vec3 extents = { 1.0f, 1.0f, 1.0f };
+  physicsBodyInit(&body, position, extents);
+  body.velocity[0] = 1.0f;
+
+  for(uint32_t i = 0; i < 400; i++) {
+    physicsWorldStep(&world, &body, DUSK_TIME_STEP, NULL, 0);
+
+    // Never falls through as a hole while crossing the ramp - descent
+    // may lag slightly behind the ideal slope (gravity closes the gap
+    // each step, see physicsWorldStep's documented limitation) but must
+    // stay close to it, never dropping toward the void below.
+    assert_true(body.position[2] >= -0.2f);
+  }
+
+  // Fully across, resting on the lower ground.
+  assert_float_equal(body.position[0], 5.0f, 0.001f);
+  assert_float_equal(body.position[2], 0.0f, 0.005f);
+  assert_true(body.grounded);
+
+  assert_int_equal(memoryGetAllocatedCount(), 0);
+}
+
+static void test_physicsWorldStepFlatGroundUnaffectedByRampLogic(
+  void **state
+) {
+  testMapReset();
+  for(worldunit_t x = 0; x < 6; x++) {
+    testMapSetTile(x, 0, 0, TILE_SHAPE_GROUND);
+  }
+
+  physicsworld_t world;
+  physicsWorldInit(&world, 20.0f, 40.0f);
 
   physicsbody_t body;
   const vec3 position = { 0.0f, 0.0f, 0.0f };
@@ -246,7 +321,6 @@ static void test_physicsWorldStepRampTreatedAsFlatGround(void **state) {
     assert_float_equal(body.position[2], 0.0f, 0.0001f);
   }
 
-  assert_float_equal(body.velocity[0], 5.0f, 0.0001f);
   assert_true(body.position[0] > 1.5f);
 
   assert_int_equal(memoryGetAllocatedCount(), 0);
@@ -346,7 +420,9 @@ int main(void) {
     cmocka_unit_test(test_physicsWorldStepTerminalVelocityClamp),
     cmocka_unit_test(test_physicsWorldStepBlockedByCeiling),
     cmocka_unit_test(test_physicsWorldStepMultiColumnFootprint),
-    cmocka_unit_test(test_physicsWorldStepRampTreatedAsFlatGround),
+    cmocka_unit_test(test_physicsWorldStepClimbsRampGoingUp),
+    cmocka_unit_test(test_physicsWorldStepDescendsRampGoingDown),
+    cmocka_unit_test(test_physicsWorldStepFlatGroundUnaffectedByRampLogic),
     cmocka_unit_test(test_physicsWorldStepBlockedByOtherBody),
     cmocka_unit_test(test_physicsWorldStepBlockedByNearestOfMultipleBodies),
     cmocka_unit_test(test_physicsWorldResolveBodyOverlapIgnoresSelfAndNull),