diff options
| -rw-r--r-- | engines/sci/engine/vm.cpp | 38 |
1 files changed, 34 insertions, 4 deletions
diff --git a/engines/sci/engine/vm.cpp b/engines/sci/engine/vm.cpp index 1f3f203dcf..5f57c0fe72 100644 --- a/engines/sci/engine/vm.cpp +++ b/engines/sci/engine/vm.cpp @@ -142,9 +142,39 @@ static reg_t validate_read_var(reg_t *r, reg_t *stack_base, int type, int max, i return default_value; } -static void validate_write_var(reg_t *r, reg_t *stack_base, int type, int max, int index, int line, reg_t value) { - if (!validate_variable(r, stack_base, type, max, index, line)) +static void validate_write_var(reg_t *r, reg_t *stack_base, int type, int max, int index, int line, reg_t value, SegManager *segMan, Kernel *kernel) { + if (!validate_variable(r, stack_base, type, max, index, line)) { + + // This code is needed to work around a probable script bug, or a limitation of the + // original SCI engine, which can be observed in LSL5. + // In some games, ego walks via the "Grooper" object, in particular its "stopGroop" child. + // In LSL5, during the game, ego is swapped from Larry to Patti. When this happens in the + // original interpreter, the new actor is loaded in the same memory location as the old + // one, therefore the client variable in the stopGroop object points to the new actor. + // This is probably why the reference of the stopGroop object is never updated (which + // is why I mentioned that this is either a script bug or some kind of limitation). + // In our implementation, each new object is loaded in a different memory location, and + // we can't overwrite the old one. This means that in our implementation, whenever ego is + // changed, we need to update the "client" variable of the stopGroop object, which points + // to ego, to the new ego object. If this is not done, ego's movement will not be updated + // properly, so the result is unpredictable (for example in LSL5, Patti spins around instead + // of walking) + if (index == 0 && type == VAR_GLOBAL) { // global 0 is ego + reg_t stopGroopPos = segMan->findObjectByName("stopGroop"); + if (!stopGroopPos.isNull()) { // does the game have a stopGroop object? + // Notify the stopGroop object that Ego changed + Object *stopGroopObj = segMan->getObject(stopGroopPos); + // Find the "client" member variable, and update it + ObjVarRef varp; + if (lookup_selector(segMan, stopGroopPos, kernel->_selectorCache.client, &varp, NULL) == kSelectorVariable) { + reg_t *clientVar = varp.getPointer(segMan); + *clientVar = value; + } + } + } + r[index] = value; + } } #else @@ -155,13 +185,13 @@ static void validate_write_var(reg_t *r, reg_t *stack_base, int type, int max, i # define signed_validate_arithmetic(r) ((int) ((r).offset) & 0x8000 ? (signed) ((r).offset) - 65536 : ((r).offset)) # define validate_variable(r, sb, t, m, i, l) # define validate_read_var(r, sb, t, m, i, l) ((r)[i]) -# define validate_write_var(r, sb, t, m, i, l, v) ((r)[i] = (v)) +# define validate_write_var(r, sb, t, m, i, l, v, sm, k) ((r)[i] = (v)) # define validate_property(o, p) ((o)->_variables[p]) #endif #define READ_VAR(type, index, def) validate_read_var(scriptState.variables[type], s->stack_base, type, scriptState.variables_max[type], index, __LINE__, def) -#define WRITE_VAR(type, index, value) validate_write_var(scriptState.variables[type], s->stack_base, type, scriptState.variables_max[type], index, __LINE__, value) +#define WRITE_VAR(type, index, value) validate_write_var(scriptState.variables[type], s->stack_base, type, scriptState.variables_max[type], index, __LINE__, value, s->_segMan, s->_kernel) #define WRITE_VAR16(type, index, value) WRITE_VAR(type, index, make_reg(0, value)); #define ACC_ARITHMETIC_L(op) make_reg(0, (op validate_arithmetic(s->r_acc))) |