C/C++ Programming Help Thread

Zitat:

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Zitat von ZereoX

Hi. I started using OSLib today, and I wanted to know a way of having collision with something that is a more of an odd shape or Diagonal Boxes and not a Squarish look shape(Flat Box,Flat Platform)?

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Use Object Orientated Bounding Box (OOBB) Collision or Line Box collision tests.

edit: see what yaustar said.

Like a said I'm still a newbie. So could you show me an example?

Say i had something like:

Code:

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char str[32];
sprintf(str, "score 1 = 10, score 2 = 13");

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how would i go about copying "score 2" into another string? strcpy doesnt let you set the params for where to copy to and from

Zitat:

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Zitat von ZereoX

Like a said I'm still a newbie. So could you show me an example?

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http://www.gamasutra.com/features/19991018/Gomez_5.htm

Zitat:

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Zitat von cruisx

ok i need some help guys. I am trying to lean how to do collision detection with 2 objects on the screen but i am kinda stuck, im sure the problem is an easy one, but for a beginner i am having some trouble.

Code:

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//Oslib header file
#include <oslib/oslib.h>

//This is needed for eboot
PSP_MODULE_INFO("OSLib Sample", 0, 1, 1);
PSP_MAIN_THREAD_ATTR(THREAD_ATTR_USER | THREAD_ATTR_VFPU);

//this creates pointers for our images.
OSL_IMAGE *sprite, *sprite2, *sprite3;

//definations
#define DOWN 0
#define UP 35
#define RIGHT 70
#define LEFT 105

//variables
int sprite_position;
int sprite_march;

//declare the function like buttons and spriteAnimation
void Buttons();
void SpriteAnimate();
int collision(OSL_IMAGE *img1,float img1posX, float img1posY, OSL_IMAGE *img2, float img2posX, float img2posY,OSL_IMAGE *img3, float img3posX, float img3posY );

int main()
{

//start the Oslib library
        oslInit(0);
//start the graphixs mode
        oslInitGfx(OSL_PF_8888, 1);

//sets the transparency color
        oslSetTransparentColor(RGB(255,0,255));

//loads the images into memory
        sprite = oslLoadImageFile("sprite.png", OSL_IN_RAM, OSL_PF_5551);
        sprite2 = oslLoadImageFile("sprite2.png", OSL_IN_RAM, OSL_PF_5551);
        sprite3 = oslLoadImageFile("sprite3.png", OSL_IN_RAM, OSL_PF_5551);

//Disables the transparent color so it cannot be used again
        oslDisableTransparentColor();

//sees if all files are avaiable
        if (!sprite || !sprite2||!sprite3)
                oslDebug("! one or more of the files were missing, the program cannot run");
               
               
//Sets the sprites original position, lets see if i can get 2 sprites on da bloody screen
        sprite->x = 155;
        sprite->y = 95;
        sprite_position = DOWN;

//sets second sprite position
        sprite2->x = 230;
        sprite2->y = 130;
       
//sets thrid sprite pos
        sprite3->x = 270;
        sprite3->y = 130;


//main while loop
        while (!osl_quit)
        {
                //to be able ot draw on the screen
                        oslStartDrawing();
                       
                //Buttons
                        Buttons();
                       
                //draws a green background
                        oslDrawGradientRect(0,0,480,272,RGB(0,128,0),RGB(0,128,0), RGB(128,255,128), RGB(128,255,128));
                       
                //this draws the images to the screen
                        oslDrawImage(sprite);
                        oslDrawImage(sprite2);
                        oslDrawImage(sprite3);
                       
                //stops the drawing mode
                        oslEndDrawing();
                       
                //sync the screen
                        oslSyncFrame();
                }
               
                //terminate the program
                oslEndGfx();
                oslQuit();
                return 0;
        }
       
                void Buttons()
                {
                //starts up the psp buttons
                        oslReadKeys();
                       
                if (osl_keys->held.down)
                {
                        if(!collision(sprite, sprite->x, sprite->y + 2, sprite2, sprite2->x, sprite2->y, sprite3, sprite3->x, sprite3->y ))
                        {
                        //sprite movement
                        sprite->y +=2;
                       
                        //sets sprite position on sprite sheet
                                sprite_position = DOWN;
                       
                        //calls sprie animate
                                SpriteAnimate();
                }
                }
                               
                        if (osl_keys->held.up)
                {
                        if(!collision(sprite, sprite->x, sprite->y - 2, sprite2, sprite2->x, sprite2->y,sprite3, sprite3->x, sprite3->y ))
                        {
                                sprite->y-= 2;
                                sprite_position = UP;
                                SpriteAnimate();
                       
                }
                }
               
          if (osl_keys->held.right)
    {
                        if(!collision(sprite, sprite->x + 2, sprite->y, sprite2, sprite2->x, sprite2->y,sprite3, sprite3->x, sprite3->y  ))
                        {
        sprite->x += 2;
        sprite_position = RIGHT;
        SpriteAnimate();
    }
        }
                       
                        if (osl_keys->held.left)
    {
                if(!collision(sprite, sprite->x - 2, sprite->y, sprite2, sprite2->x, sprite2->y,sprite3, sprite3->x, sprite3->y  ))
                {
        sprite->x -= 2;
        sprite_position = LEFT;
        SpriteAnimate();
    }
        }
                       
                          //If a button is not pressed
    if (!osl_keys->held.value)
    {
    //Start the variable over for when a button is pressed again
        sprite_march = 0;

        //Sets the sprite's direction
        oslSetImageTileSize(sprite,0,sprite_position,22,35);
    }
}


void SpriteAnimate()
  {   
        //Moves the sprite in the row that it is in
        sprite_march++;

        //Moves the sprite constantly
        oslSetImageTileSize(sprite,(sprite_march * 22),sprite_position,22,35);

        //resets the sprite movement in that row
        if (sprite_march == 6) sprite_march = 0;
   
}
                       
               
                int collision(OSL_IMAGE *img1,float img1posX, float img1posY, OSL_IMAGE *img2, float img2posX, float img2posY, OSL_IMAGE *img3, float img3posX, float img3posY )
{
  int collision;
  collision = 0;
  float img1width  = img1->stretchX;
  float img1height = img1->stretchY;
  float img2width  = img2->stretchX;
  float img2height = img2->stretchY;
  float img3width = img3->stretchX;
  float img3height = img3->stretchY;
 
 
  if ((img1posX + img1width > img2posX) &&
      (img1posX < img2posX + img2width) &&
          (img1posX + img1width > img3posX) &&
      (img1posX < img2posX + img3width) &&
      (img1posY + img1height > img2posY) &&
      (img1posY < img2posY + img2height) )
{
        collision = 1;             
  }   
  return collision;
}

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I know where the problem is but i dont know what im doing wrong

Code:

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if ((img1posX + img1width > img2posX) &&
      (img1posX < img2posX + img2width) &&
          (img1posX + img1width > img3posX) &&
      (img1posX < img2posX + img3width) &&
      (img1posY + img1height > img2posY) &&
      (img1posY < img2posY + img2height) )
{

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if i put that in, none of the sprites have collision but if i take out the Bolded parts the first sprite has collision but the second one dose not.(second sprite as in the second object, not the character that is moving). How do i modify this correctly for every new object on the screen? help will be greatly appreciated.

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can someone please help? =)

Zitat:

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Zitat von Xsjado7

Say i had something like:

Code:

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char str[32];
sprintf(str, "score 1 = 10, score 2 = 13");

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how would i go about copying "score 2" into another string? strcpy doesnt let you set the params for where to copy to and from

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ugh

Code:

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char str[64]; // I would go a little higher just incase of bigger variables
int score1 = 10, score2 = 13;
sprintf(str, "Score 1 = %i, Score 2 = %i", score1, score2);

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Look it over, it's pretty self explanatory. Store the scores in variables, then get them from there.

Zitat:

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Zitat von Slasher

ugh

Code:

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char str[64]; // I would go a little higher just incase of bigger variables
int score1 = 10, score2 = 13;
sprintf(str, "Score 1 = %i, Score 2 = %i", score1, score2);

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Look it over, it's pretty self explanatory. Store the scores in variables, then get them from there.

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I think he was asking about splitting an existing string.

lol, yeah. For eample; i wanna cut "score = 2" and chuck it another string or something to that extent

Zitat:

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Zitat von Xsjado7

lol, yeah. For eample; i wanna cut "score = 2" and chuck it another string or something to that extent

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Why not use std::string instead of messing around with char[] sprintf and the likes? it's so easier.
http://www.cplusplus.com/reference/string/string/

my apps in C, not C++ :(

Zitat:

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Zitat von Xsjado7

my apps in C, not C++ :(

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you can still use std::strings I think, you'll just have to modify some things (.cpp instead of .c for your files, -lstdc++ added in your makefile). this won't stop you writing everything in C if you like, but you'll be able to use std::strings at the same time (you'll also benefit from iostreams & lists/vectors/maps, this will make your life a lot easier).

Oh, ok. Thanks for the help :D
-= Double Post =-
Just renamed my stuff and added the etra lib but i get errors thrown at me. Im going to try something else. Im gonna write the string to a temporary file on the memory stick. from there i can use sceIo functions like sceIoRead which allows me to tell it how far to read and such. Thanks again for the help though

Zitat:

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Zitat von Xsjado7

Just renamed my stuff and added the etra lib but i get errors thrown at me. Im going to try something else. Im gonna write the string to a temporary file on the memory stick. from there i can use sceIo functions like sceIoRead which allows me to tell it how far to read and such.

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:down: really really bad solution. you better show us the errors and your code so we can help, or continue investigate proper C code with memcopy and all that crap.

Code:

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source/../settings/stats.h(26) : error: expected unqualified-id before 'throw'
source/main.cpp: In function 'void newGame()':
source/main.cpp(33) : error: 'mainGame' was not declared in this scope
source/main.cpp: In function 'void mainGame()':
source/main.cpp(89) : warning: passing 'double' for argument 4 to 'void fillScre
enRect(Color, int, int, int, int)'
source/main.cpp(90) : warning: passing 'double' for argument 4 to 'void fillScre
enRect(Color, int, int, int, int)'
source/main.cpp(115) : error: expected unqualified-id before 'throw'
source/main.cpp(115) : error: expected `)' before 'throw'
source/main.cpp(117) : error: expected unqualified-id before 'throw'
source/main.cpp(117) : error: expected `;' before 'throw'
source/main.cpp(118) : error: expected unqualified-id before 'throw'
source/main.cpp(118) : error: expected `;' before 'throw'
source/main.cpp: In function 'int main()':
source/main.cpp(277) : error: cannot convert 'const char*' to 'short unsigned in
t*' for argument '2' to 'int OSK(char*, short unsigned int*, short unsigned int*
)'
source/main.cpp(364) : error: cannot convert 'const char*' to 'short unsigned in
t*' for argument '2' to 'int OSK(char*, short unsigned int*, short unsigned int*
)'
source/main.cpp(373) : error: 'dispCredits' was not declared in this scope

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My errors, and thats just from my main.cpp. I have more than 8 more source files

I'll need your main.cpp to see what's wrong.

Oh, forgot to mention, "throw" is actually a variable in my "player" struct. I take it its a command in C++ due to it being highlighted in Notepad++ when i type it

Zitat:

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Zitat von Xsjado7

Oh, forgot to mention, "throw" is actually a variable in my "player" struct. I take it its a command in C++ due to it being highlighted in Notepad++ when i type it

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yup, it's a reserved key word of the c++ language. hope this solves everything, if not post here.

Ok, i think iv got it sorted out. Do i have to code any different to use those new functions?

Zitat:

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Zitat von Xsjado7

Ok, i think iv got it sorted out. Do i have to code any different to use those new functions?

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only when using strings, remember that it's a c++ class, so to allocate memory for it (if you want to use pointers, which in most cases is not needed) istead of malloc use new, and instead of free use delete. apart from that, you can continue working completely in C.

small example to get you started:

PHP-Code:

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#include <string>
using namespace std;

string str ("this is a string");

//now use the power of the string class: str.substr(), str.find()..
//nothing else to do! 


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Hey, iv been messing with the stuff on the computer, setting up a my function. Just a quick question, is it possible to do something like:

Code:

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char str[32]="Im a string";
string str2;
strcpy(str2, str);

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Obviously it doesnt work but is there anything like this?

Zitat:

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Zitat von Xsjado7

Hey, iv been messing with the stuff on the computer, setting up a my function. Just a quick question, is it possible to do something like:

Code:

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char str[32]="Im a string";
string str2;
strcpy(str2, str);

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Obviously it doesnt work but is there anything like this?

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I think this will do it:

Code:

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char str[32]="Im a string";
string str2(str);

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even this works (only to show you that you can do things like that, example above is better for this exact case you have)

Code:

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char str[32]="Im a string";
string str2=str; //or string str2="Im a string"

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of course if you just want to declare a string that is initialized, do it simply like this:

Code:

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string str2("Im a string");

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http://www.cplusplus.com/reference/s...ng/string.html

Code:

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char str[32]="Im a string";
string str2( str );
string str3 = str;

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Sweet, thanks guys
-= Double Post =-
okay, iv got m function working perfectly on computer but i just put it into my game and i get:

Code:

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scores.cpp(34) : error: 'string' was not declared in this scope

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Iv added -lstdc++ in my makefile so what am i missing?
-= Double Post =-
iv got past that error now, i just had to include <string>. Now im getting a few errors:

Code:

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source/scores.cpp(57) : error: incompatible types in assignment of 'std::basic_s
tring<char, std::char_traits<char>, std::allocator<char> >' to 'char [128]'
source/scores.cpp(73) : error: incompatible types in assignment of 'std::basic_s
tring<char, std::char_traits<char>, std::allocator<char> >' to 'char [128]'
source/scores.cpp(83) : error: incompatible types in assignment of 'std::basic_s
tring<char, std::char_traits<char>, std::allocator<char> >' to 'char [128]'
source/scores.cpp(93) : error: incompatible types in assignment of 'std::basic_s
tring<char, std::char_traits<char>, std::allocator<char> >' to 'char [128]'
source/scores.cpp(103) : error: incompatible types in assignment of 'std::basic_
string<char, std::char_traits<char>, std::allocator<char> >' to 'char [128]'

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those lines consist of:

Code:

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score.hs1name = loadbuff3.substr(1, seperator-1);

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just with a different variable name e.g score.hs2name...
Note: Everything worked fine on the computer

What datatype is score.hs2name?

can anyone help me out, i've been trying to shutdown the psp with the square button and including psppower.h but i dont know what is needed to power off in 3.90 as this call is old afaik :D

i've been trying

Code:

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                else if (pad.Buttons & PSP_CTRL_SQUARE)
                {
                  sceSysconPowerStandby();
                }

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Code:

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int write(int fd, char *Buff, int NumBytes);

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Does this work on PSP? Can I use a file descriptor?

Considering your function name is so vague and not in the SDK or STL no *rolls eyes*

Zitat:

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Zitat von SG57

Considering your function name is so vague and not in the SDK or STL no *rolls eyes*

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Yeah... It's for dos;
Now-a-days i'm intermixing multiple platforms (3 to be exact) :p

actually it should work fine. its posix (unistd.h) fwrite works, which just wraps write. just ignore sg57. you can use it.

ok guys iv been trying to get this right for a few days but have had no luck.

so i have a code for collision right, but i dont know how to correctly modify it so it works for one more sprite on the screen.

this is the code for 1 sprite collision:

Code:

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if ((img1posX + img1width > img2posX) &&
      (img1posX < img2posX + img2width) &&
      (img1posY + img1height > img2posY) &&
      (img1posY < img2posY + img2height) )

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now when i try to modify it for another sprite on the screen, the second sprite still has no collision =\ but the first sprite still does.

my code:

Code:

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if ((img1posX + img1width > img2posX) &&
      (img1posX < img2posX + img2width) &&
          (img1posX + img1width > img3posX) &&
      (img1posX < img2posX + img3width) &&
      (img1posY + img1height > img2posY) &&
      (img1posY < img2posY + img2height) )

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Spoiler for Post:

Zitat:

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Zitat von yaustar

What datatype is score.hs2name?

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Just realised its a char[32] and not a std::string. Fixed that now. Code compiles but when running i get caught on:

Code:

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name1 = loadbuff3.substr(1, seperator-1);

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Prior to that i have:

Code:

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separator = loadbuff3.find("|");

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Im using the official sony savedata functions so my highscores are loaded as one string. An example of whats stored/loaded:

Code:

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"032.5=Me|034.9=You|105.0=Someone|096.6=Someoneelse|025.2=Santa"

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I have "|" between each highscore. After i have found the first score float with atof() i remove the score and = sign so im essentially left with:

Code:

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"Me|"

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Then i simply find the separator and read from the start of the file to the separator and that gets me the name. Any ideas why this isnt working?

Zitat:

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Zitat von yaustar

What datatype is score.hs2name?

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I guess it's a char[128].

the = operator works only in one way:
string = char[] is ok
char[] = string doesn't work

but you can get a const char* from a string with mystring.c_str() if that helps.
-= Double Post =-
xsjado, maybe I can help you with this function:

Code:

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vector<string> split(string str, string delim)
{
        vector<string> results;
        unsigned int cutAt;
        while((cutAt = str.find_first_of(delim)) != str.npos)
        {
                if(cutAt > 0)
                {
                        results.push_back(str.substr(0,cutAt));
                }
                str = str.substr(cutAt+1);
        }
        if(str.length() > 0)
        {
                results.push_back(str);
        }
        return results;
}

---

it splits a string given a delimiter, and returns it as a vector.
for example, split("032.5=Me|034.9=You |105.0=Someone|096.6=Some oneelse|025.2=Santa", "|") will give you a vector containing this:
"032.5=Me"
"034.9=You"
"105.0=Someone"
etc...
and with the same technique you can get what you want from the string.
-= Double Post =-
cruisx, if you have a working function for collision between 2 sprites, just call it for all your sprites on screen, change the parameters that's all...

I spend two hours learning C++ functions and writing out my function then i log on today to find this :rolleyes:

Zitat:

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Zitat von Xsjado7

I spend two hours learning C++ functions and writing out my function then i log on today to find this :rolleyes:

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spending time learning is a good thing ;)

Do you know why my code isnt working though? It just gets to:

Code:

---

name1 = loadbuff3.substr(1, seperator-1);

---

and nothing happens, doesnt do it

Zitat:

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Zitat von Xsjado7

Do you know why my code isnt working though? It just gets to:

Code:

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name1 = loadbuff3.substr(1, seperator-1);

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and nothing happens, doesnt do it

---

I'll need the whole function or code block.

Code:

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  pspDebugScreenInit();
  //This is for the seperator between scores
  int seperator;
  //This is for the "=" sign between the time and name in a highscore
  int equals;
  //The buffer for use with atof
  char* loadbuff2;
  //The buffer for use with string:: functions
  string loadbuff3;
  //For storing the highscore names
  string name1, name2, name3, name4, name5;
 
  //Conversions
  //Convert global.loadbuff for use with string:: functions
  loadbuff3 = global.loadbuff;
  loadbuff2 = new char [loadbuff3.size()+1];
  strcpy(loadbuff2, loadbuff3.c_str());
  pspDebugScreenPrintf("loadbuff3 copied to loadbuff2\n");
 
  //Get first highscore data
  //Get score.hs1
  score.hs1 = atof(loadbuff2);
  pspDebugScreenPrintf("Got time from first highscore\n");

  //Remove score.hs1 from loadbuff3
  loadbuff3.erase(0, 5);
  pspDebugScreenPrintf("Erased furst highscore from loadbuff3\n");

  //Get the seperator from between the data of the first and second highscores
  seperator = loadbuff3.find("|");
  pspDebugScreenPrintf("Found seperator from between highscore 1 and 2\n");

  //Read from six bytes in to the seperator AKA get the name for the first highscore
  name1 = loadbuff3.substr(1, seperator-1);
  pspDebugScreenPrintf("Got first highscore name\n");

---

it's because:
- strings indices start at 0
- substr is like this: string.substr(size_t pos = 0, size_t n = npos) with pos = where to start, n = length of the substring, and not where to stop.

your code (I suppose loadbuff=="Me|"):
name1 = loadbuff3.substr(1, seperator-1);
does this:
name1 = loadbuff3.substr(1, 1);
so name="e".

I haven't tested but maybe try to write name1 = loadbuff3.substr(0, seperator); to see if I'm right.

http://www.cplusplus.com/reference/s...ng/substr.html

Forgot to mention, each float is stored as 5 characters, 3 digits for the seconds, a full stop and one digit for the miliseconds if that helps for anything.

Also its:

Code:

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name1 = loadbuff3.substr(1, seperator-1);

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because i havent removed the "=" sign so its going to be "=Me|".
-= Double Post =-
So does anyone have any ideas as to why the PSP gets caught at using .substr? Doesnt make any sense