I am having some trouble with programming hit detection in Processing.JS. I have tried to make a function that checks if something is touching an object and returns true and otherwise returns false. This is that here.
Snake.prototype.checkTouching = function(v){
if(v.position.x > this.position.x - this.width/2 && v.position < this.position.x + this.width/2 && v.position.y > this.positon.y - this.height/2 && v.position.y < this.position.y + this.height/2){
return true;
}else{
return false;
}
};
I am implementing it by creating a new variable "b" in my draw function that holds the value the function returned then using an if statement to check if the value "b" is holding is true. Like so
var b = snakey.checkTouching(mos);
var restarts = 0;
if(b === true){
restarts += 1;
Program.restart();
}
unfortunately even when the object the function is running on is touching the object that is running it nothing happens. I have already checked to see if the logic works and it is valid so I know it has to be my implementation I just can not seem to find out what is wrong with my implementation. Can anyone tell what I am doing wrong? Full program here.Full Program
Related
I've read somewhere that a variable should be entered into the code if it is reused. But when I write my code for logic transparency, I sometimes create intermediate variables (with names reflecting what they contain) which are used only once.
How incorrect is this concept?
PS:
I want to do it right.
It is important to note that most of the time clarity takes precedence over re-usability or brevity. This is one of the basic principles of clean code. Most modern compilers optimize code anyway so creating new variables need not be a concern at all.
It is perfectly fine to create a new variable if it would add clarity to your code. Make sure to give it a meaningful name. Consider the following function:
public static boolean isLeapYear(final int yyyy) {
if ((yyyy % 4) != 0) {
return false;
}
else if ((yyyy % 400) == 0) {
return true;
}
else if ((yyyy % 100) == 0) {
return false;
}
else {
return true;
}
}
Even though the boolean expressions are used only once, they may confuse the reader of the code. We can rewrite it as follows
public static boolean isLeapYear(int year) {
boolean fourth = year % 4 == 0;
boolean hundredth = year % 100 == 0;
boolean fourHundredth = year % 400 == 0;
return fourth && (!hundredth || fourHundredth);
}
These boolean variables add much more clarity to the code.
This example is from the Clean Code book by Robert C. Martin.
I'm trying to use join_facet() iteratively to grow a single facet starting from a given facet_handle. However, I'm running into trouble when using the Halfedge_around_facet_circulator in combination with join_facet(). My while-loop does not become false anymore which works fine if I don't use join_facet() and the circulator seems to point to something else.
I assume that the join operation is somehow changing that Halfedge_around_facet_circulator. But why and how to solve this?
Polyhedron P_out; // is a valid pure triangle Polyhedron
bool merge_next = true;
while (merge_next == true) {
Polyhedron::Halfedge_around_facet_circulator hit = facet_handle->facet_begin(); // facet_handle pointing to facet of P_out
merge_next = false;
do {
if(!(hit->is_border_edge())) {
if (coplanar(hit->facet(), hit->opposite()->facet())) {
if (CGAL::circulator_size(hit->opposite()->vertex_begin()) >= 3 && CGAL::circulator_size(hit->vertex_begin()) >= 3
&& hit->facet()->id() != hit->opposite()->facet()->id()) {
Polyhedron::Halfedge_handle hit2 = hit;
P_out->join_facet(hit2);
merge_next = true;
}
}
}
} while (++hit != facet_handle->facet_begin());
}
What this code should do:
Given the facet_handle, iterate over the corresponding halfedges of facet and merge if possible. Then taking facet_handle of created new facet again and doing the same until no neighboring facets are left to merge.
Edit:
There are areas on which the code runs fine and others where it crashes at hit->is_border_edge() after the first join_facet().
I've just started using gamemaker studio 2 and I've been scratching my head over this one for a while.
I need to be able to destroy a specific instance of my enemy object without using the collision event. Here is my current code:
In my player object:
if (sprite_index = spr_player_attack_left) {
if (obj_enemy.x > x - 25 && obj_enemy.x < x) {
obj_enemy.hp--;
}
}
//detect right
if (sprite_index = spr_player_attack_right) {
if (obj_enemy.x < x + 25 && obj_enemy.x > x) {
obj_enemy.hp--;
}
}
//detect up
if (sprite_index = spr_player_attack_up) {
if (obj_enemy.y > y - 25 && obj_enemy.y < y) {
obj_enemy.hp--;
}
}
//detect down
if (sprite_index = spr_player_attack_up) {
if (obj_enemy.y < y + 25 && obj_enemy.y > y) {
obj_enemy.hp--;
}
}
And in my enemy object:
if (hp <= 0) {
var attacked = instance_find(obj_enemy, this.id);
instance_destroy(attacked);
}
Currently there is only one instance of the enemy in the room that registers an attack, and when I attack that instance, all instances are destroyed, while I only want one to be destroyed.
Thanks in advance for any help!
The reason this is happening is because you are using the object index, and not an index of a specific instance. When you do:
<object_index>.<object_property> eg. obj_enemy.hp
Two things can happen:
If there is one instance currently active in the game, then that
instance's variable will be referenced.
If there are two or more instances, then GameMaker can't tell which one you want to reference.
The offending code here are the if statements:
if (obj_enemy.x > x - 25 && obj_enemy.x < x) {
obj_enemy.hp--;
}
The way you can rewrite them is:
with (obj_enemy) {
if (x > other.x - 25 && x < other.x) hp--;
}
The same goes for all of the other if statements as well. The with keyword acts as a loop here. You can read it as "go through each instance of obj_enemy and do the code between { ... }". To reference the instance outside the with statement we use other(in this example, other will be the player).
And for the code in the enemy object, you don't have to use instance_find at all. Actually the this.id part is completely invalid, unless you define this as an instance variable before that code runs.
Anyways, the correct version would be:
if (hp <= 0) {
instance_destroy();
}
The instance_destroy function destroys the instance that is currently in scope(in GMS2 or GMS1 Early Access, you can pass it an additional id of the instance you wish to destroy).
I am having some trouble with programming hit detection in Processing.JS. I have tried to make a function that checks if something is touching an object and returns true and otherwise returns false. This is that here.
`Box.prototype.checkTouching = function(v){
if(v.position.x > this.position.x - this.width/2 && v.position <
this.position.x + this.width/2 && v.position.y > this.positon.y -
this.height/2 && v.position.y < this.position.y + this.height/2){
return true;
}else{
return false;
}
};`
I am implementing it by creating a new variable "b" in my draw function that holds the value the function returned then using an if statement to check if the value "b" is holding is true. Like so
var b = box3.checkTouching(mos);
if(b === true){
println("It works");
}
What should happen when the two objects touch is that a message saying "it works" gets printed in to the console. Unfortunately even when the object the function is running on is touching the object that is running it nothing happens. I have already checked to see if the logic works and it is valid so I know it has to be my implementation I just can not seem to find out what is wrong with my implementation. Can anyone tell what I am doing wrong? Full program here
You need to check whether the rectangles overlap. You'd do this by checking each side, like this:
if(rectOneRight > rectTwoLeft && rectOneLeft < rectTwoRight && rectOneBottom > rectTwoTop && rectOneTop < rectTwoBottom){
//collision
}
Shameless self-promotion: I've written a tutorial on collision detection in Processing (including rectangle-rectangle collision) available here.
To build on what Kevin posted, say I want to hover my mouse over a rectangle. processing has the built in variables mouseX, mouseY that return the coordinates of the mouse.
so I would check if the mouse X position was greater then the rect X pos, and less than the rect X pos + the rect width. the, do the same with the mouseY, rect Y and rect height
if (mouseX > rectXpos &&
mouseX < rectXpos + rectWidth &&
mouseY > rectYpos &&
mouseY < rectYpos + rectHeight) {
// the button is being hovered over
}
I'm messing around with the PushSource sample filter shipped with the DirectShow SDK and I'm having the following problem:
When I call IMediaControl::Run(), it returns S_FALSE which means "the graph is preparing to run, but some filters have not completed the transition to a running state". MSDN suggests to then call IMediaControl::GetState() and wait for the transition to finish.
And so, I call IMediaControl::GetState(INFINITE, ...) which is supposed to solve the problem.
However, to the contrary, it returns VFW_S_STATE_INTERMEDIATE even though I've specified an infinite waiting time.
I've tried all three variations (Bitmap, Bitmap Set and Desktop) and they all behave the same way, which initially lead me to believe there is a bug in there somewhere.
However, then, I tried using IFilterGraph::AddSourceFilter to do the same and it did the same thing, which must mean it's my rendering code that is the problem:
CoInitialize(0);
IGraphBuilder *graph = 0;
assert(S_OK == CoCreateInstance(CLSID_FilterGraph, 0, CLSCTX_INPROC_SERVER, IID_IGraphBuilder, (void**)&graph));
IBaseFilter *pushSource = 0;
graph->AddSourceFilter(L"sample.bmp", L"Source", &pushSource);
IPin *srcOut = 0;
assert(S_OK == GetPin(pushSource, PINDIR_OUTPUT, &srcOut));
graph->Render(srcOut);
IMediaControl *c = 0;
IMediaEvent *pEvent;
assert(S_OK == graph->QueryInterface(IID_IMediaControl, (void**)&c));
assert(S_OK == graph->QueryInterface(IID_IMediaEvent, (void**)&pEvent));
HRESULT hr = c->Run();
if(hr != S_OK)
{
if(hr == S_FALSE)
{
OAFilterState state;
hr = c->GetState(INFINITE, &state);
assert(hr == S_OK );
}
}
long code;
assert(S_OK == pEvent->WaitForCompletion(INFINITE, &code));
Anyone knows how to fix this?
IBaseFilter *pushSource = 0;
graph->AddSourceFilter(L"sample.bmp", L"Source", &pushSource);
AddSourceFilter adds a default source filter, I don't think it will add your pushsource samplefilter.
I would recommend to add the graph to the ROT, so you can inspect it with graphedit.
And what happens if you don't call GetState()?
hr = pMediaControl->Run();
if(FAILED(hr)) {
/// handle error
}
long evCode=0;
while (evCode == 0)
{
pEvent->WaitForCompletion(1000, &evCode);
/// other code
}
Open GraphEditPlus, add your filter, render its pin and press Run. Then you'll see states of each filter separately, so you'll see what filter didn't run and why.