C/C++ Programming Help Thread

[Archaemic]

You put the forward declaration (sometimes called the prototype) in the header file, not the function, or else you'll get a linker error.

Try something like this

funcs.cpp:

int myFunc()
{
  return doSomething();
}

main.cpp:

#include "funcs.hpp"
int main() {
  return myFunc();
}

funcs.hpp:

int myFunc();

[Beat_Bob]

But how does this work?
Or are you expecting me that ive included the .h already?

[Archaemic]

Oops, forgot that. Hold on, let me edit my post

Okay, there we go.

[yaustar]

You keep track of the x and y of the sprites You don't detect where they are based on the screen.

What MiG is trying to say is when he renders something in 3D model space, how do you get the screen space co-ordinates.

The answer is via lots of matrix math. You need to get the x,y,z position of object in model space, multiple it with the view matrix and multiple that result with the perspective matrix. The x and y components of the end result should be the x and y position in screen space.

In reality, you don't do collision detection this way. You do it in 3D model space, not screen space.

FistPump nailed it in one.

Personally, I would use a struct to hold the coordinates of the object. A struct is like a container that you can basically clone to make an object. So if you define a struct and then make an object of that struct, the object will have the same data fields.


EXAMPLE:

const int MAX_PLAYERS = 2;

struct _Player
{
	//x, y, width, height
	int x, y, w, h;
	unsigned int color;
};


struct _Player players[MAX_PLAYERS];

//First Square
players[0].x = 0;
players[0].y = 0; 
players[0].w = 50;
players[0].h = 50;

//Second Square
players[0].x = 100;
players[0].y = 100; 
players[0].w = 50;
players[0].h = 50;

//Basic Draw Rectangle Function
drawRectFunction(players[0].x, players[0].y, players[0].w, players[0].h, players[0].color);
drawRectFunction(players[1].x, players[1].y, players[1].w, players[1].h, players[1].color);

int didCollide(_Player one, _Player two)
{
	int collided;

	//collisions

	return collided;
}

if(pad.Buttons & PSP_CTRL_LEFT)
{
	players[0].x --;
}
if(pad.Buttons & PSP_CTRL_UP)
{
	players[1].y--;
}

[Beat_Bob]

Why doesnt this work?

int counter = 0;
SceCtrlData pad;

int main() {
         printf("Counter: %i ", counter);

    pspDebugScreenInit();
    SetupCallbacks();
    sceKernelSleepThread(); // Wait for home
    return 0;
}

It leaves me with a blank screen. Why doesnt it show: 0?
Also for an player object, what would be better to use.
structures, or classes? (like a simple player)
Just a box, added with physics (collisions, moving, jumping, gravity, etc.)

[PSPJunkie_]

Go to PSP-Programming and follow their tutorials before you worry about making a game.

[Beat_Bob]

I waited all that time for that........
I did go to psp-programming.com, infact thats where I learnt that from.

[Archaemic]

int counter = 0;

int main() {
    SetupCallbacks();
    pspDebugScreenInit();
    pspDebugScreenPrintf("Counter: %i ", counter);
    return 0;
    sceKernelSleepThread(); // Wait for home
}

Fixed. pspDebugScreenPrintf needs to be after pspDebugScreenInit.

[PSPJunkie_]

I waited all that time for that........
I did go to psp-programming.com, infact thats where I learnt that from.

No. No you didn't.

[Beat_Bob]

Anyone know about this error?
[email protected] ~/PSProjects/imager
$ make
psp-g++ -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -I. -I/usr/local/
spdev/psp/sdk/include -O2 -G0 -Wall -fno-exceptions -fno-rtti -c -o main.o ma
n.cpp
main.cpp:8:39: error: graphics.h: No such file or directory
main.cpp: In function 'int main()':
main.cpp:49: error: 'initGraphics' was not declared in this scope
main.cpp:51: error: 'Image' was not declared in this scope
main.cpp:51: error: 'ourImage' was not declared in this scope
main.cpp:53: error: 'loadImage' was not declared in this scope
main.cpp:58: error: 'blitAlphaImageToScreen' was not declared in this scope
main.cpp:59: error: 'flipScreen' was not declared in this scope
make: *** [main.o] Error 1

I did the svn checkout, but it sais it cant find graphics.h
Huh?

[PSPJunkie_]

Yes it did. If you are too stupid to follow those tutorials, get a book on C and get reading.

[Beat_Bob]

Could you answer my next question. (what a nice forum)

[PSPJunkie_]

Could you answer my next question. (what a nice forum)

Isn't it? Stop complaining.

extern "C" {
#include "graphics.h"
}

That or graphics.h doesn't exist at all.

[Beat_Bob]

Now I have a two more errors, but the graphics.h one is gone:

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION=
150   -c -o main.o main.c
main.c:8: error: expected identifier or '(' before string constant
main.c:8: error: stray '#' in program
main.c: In function 'main':
main.c:49: warning: implicit declaration of function 'initGraphics'
main.c:51: error: 'Image' undeclared (first use in this function)
main.c:51: error: (Each undeclared identifier is reported only once
main.c:51: error: for each function it appears in.)
main.c:51: error: 'ourImage' undeclared (first use in this function)
main.c:53: warning: implicit declaration of function 'loadImage'
main.c:58: warning: implicit declaration of function 'blitAlphaImageToScreen'
main.c:59: warning: implicit declaration of function 'flipScreen'
make: *** [main.o] Error 1

My main.c:

Spoiler for Spoil:

#include <pspdisplay.h>
#include <pspctrl.h> // Allows us to read input from the PSP's keys
#include <pspkernel.h>
#include <pspdebug.h>
#include <pspgu.h>
#include <png.h> // <Manipulate the PNG Image files
#include <stdio.h> // Has some C functions (sprintf() to parse strings)
extern "C" {#include "graphics.h"}

#define printf pspDebugScreenPrintf
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y)) // Returns X if greater than Y, or returns Y if less

PSP_MODULE_INFO("Image Displayer", 0, 1, 1);

/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
sceKernelExitGame();
return 0;
}

/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
int cbid;

cbid = sceKernelCreateCallback(" Exit Callback", exit_callback, NULL);
sceKernelRegisterExitCall back(cbid);

sceKernelSleepThreadCB();

return 0;
}

/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
int thid = 0;

thid = sceKernelCreateThread("up date_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
if(thid >= 0) {
sceKernelStartThread(thid , 0, 0);
}

return thid;
}


int main() {
SetupCallbacks();
pspDebugScreenInit();
initGraphics();
char buffer[200]; // Block of memory of 200 variables for a string (maximum length it can be)
Image* ourImage;
sprintf(buffer, "ourImage.png");
ourImage = loadImage(buffer);
if(ourImage)
{
int x = 0, y = 0;
sceDisplayWaitVblankStart ();
blitAlphaImageToScreen(0 ,0 ,32 , 32, ourImage, x, y);
flipScreen();
}


sceKernelSleepThread(); // Wait for home
return 0;
}

I did the svn checkout, how could it not exist?
Or is graphics.h a seperate file and needs to be downloaded seperately? If so could
someone provide a link?

[PSPJunkie_]

Try,

extern "C" { 
#include "graphics.h" 
}

As I said, as I believe it isn't parsing the '{#' correctly.

[Beat_Bob]

Well I did that and now heres my error list:

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION=
150   -c -o main.o main.c
main.c:8: error: expected identifier or '(' before string constant
main.c:9:23: error: graphics.h: No such file or directory
main.c: In function 'main':
main.c:51: warning: implicit declaration of function 'initGraphics'
main.c:53: error: 'Image' undeclared (first use in this function)
main.c:53: error: (Each undeclared identifier is reported only once
main.c:53: error: for each function it appears in.)
main.c:53: error: 'ourImage' undeclared (first use in this function)
main.c:55: warning: implicit declaration of function 'loadImage'
main.c:60: warning: implicit declaration of function 'blitAlphaImageToScreen'
main.c:61: warning: implicit declaration of function 'flipScreen'
make: *** [main.o] Error 1

[PSPJunkie_]

Now I have a two more errors, but the graphics.h one is gone:

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION=
150   -c -o main.o main.c
main.c:8: error: expected identifier or '(' before string constant
main.c:8: error: stray '#' in program
main.c: In function 'main':
main.c:49: warning: implicit declaration of function 'initGraphics'
main.c:51: error: 'Image' undeclared (first use in this function)
main.c:51: error: (Each undeclared identifier is reported only once
main.c:51: error: for each function it appears in.)
main.c:51: error: 'ourImage' undeclared (first use in this function)
main.c:53: warning: implicit declaration of function 'loadImage'
main.c:58: warning: implicit declaration of function 'blitAlphaImageToScreen'
main.c:59: warning: implicit declaration of function 'flipScreen'
make: *** [main.o] Error 1

My main.c:

Spoiler for Spoil:

#include <pspdisplay.h>
#include <pspctrl.h> // Allows us to read input from the PSP's keys
#include <pspkernel.h>
#include <pspdebug.h>
#include <pspgu.h>
#include <png.h> // <Manipulate the PNG Image files
#include <stdio.h> // Has some C functions (sprintf() to parse strings)
extern "C" {#include "graphics.h"}

#define printf pspDebugScreenPrintf
#define MAX(X, Y) ((X) > (Y) ? (X) : (Y)) // Returns X if greater than Y, or returns Y if less

PSP_MODULE_INFO("Image Displayer", 0, 1, 1);

/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
sceKernelExitGame();
return 0;
}

/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
int cbid;

cbid = sceKernelCreateCallback(" Exit Callback", exit_callback, NULL);
sceKernelRegisterExitCall back(cbid);

sceKernelSleepThreadCB();

return 0;
}

/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
int thid = 0;

thid = sceKernelCreateThread("up date_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
if(thid >= 0) {
sceKernelStartThread(thid , 0, 0);
}

return thid;
}


int main() {
SetupCallbacks();
pspDebugScreenInit();
initGraphics();
char buffer[200]; // Block of memory of 200 variables for a string (maximum length it can be)
Image* ourImage;
sprintf(buffer, "ourImage.png");
ourImage = loadImage(buffer);
if(ourImage)
{
int x = 0, y = 0;
sceDisplayWaitVblankStart ();
blitAlphaImageToScreen(0 ,0 ,32 , 32, ourImage, x, y);
flipScreen();
}


sceKernelSleepThread(); // Wait for home
return 0;
}

I did the svn checkout, how could it not exist?
Or is graphics.h a seperate file and needs to be downloaded seperately? If so could
someone provide a link?

Argh! Lesson 4, PSP-Programming tutorials. I thought you went there first?

[Beat_Bob]

I couldnt find the link anywhere.
I assumed it was put in the svn checkout download.

[PSPJunkie_]

Link

[Beat_Bob]

I made a folder on my user directory called graphics, put the files in there,
ran the batch and now heres what I got:

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION
150   -c -o main.o main.c
main.c:8: error: expected identifier or '(' before string constant
main.c:9:22: error: graphics.h: No such file or directory
main.c: In function 'main':
main.c:51: warning: implicit declaration of function 'initGraphics'
main.c:53: error: 'Image' undeclared (first use in this function)
main.c:53: error: (Each undeclared identifier is reported only once
main.c:53: error: for each function it appears in.)
main.c:53: error: 'ourImage' undeclared (first use in this function)
main.c:55: warning: implicit declaration of function 'loadImage'
main.c:60: warning: implicit declaration of function 'blitAlphaImageToScreen'
main.c:61: warning: implicit declaration of function 'flipScreen'
make: *** [main.o] Error 1

(my main.c is in my other post)
Also do I need to be worried about these warnings?

[PSPJunkie_]

You should always be worried about warnings.

Put graphics.c/h and framebuffer.c/h into the project directory, then make sure to add 'graphics.o' and 'framebuffer.o' to the OBJS line in your makefile.

[Beat_Bob]

Nope, still didnt work.
I dont think it matters but my project directory name is PSProjects.
Also heres my makefile:

TARGET = hello
OBJS = main.o graphics.o framebuffer.o

CFLAGS = -O2 -G0 -Wall
CXXFLAGS = $(CFLAGS) -fno-exceptions -fno-rtti
ASFLAGS = $(CFLAGS)

LIBDIR =
LIBS = -lpspgu -lpng -lz -lm
LDFLAGS =

EXTRA_TARGETS = EBOOT.PBP
PSP_EBOOT_TITLE = Image Example

PSPSDK=$(shell psp-config --pspsdk-path)
include $(PSPSDK)/lib/build.mak

Errors:

$ make
psp-gcc -I. -I/usr/local/pspdev/psp/sdk/include -O2 -G0 -Wall -D_PSP_FW_VERSION
150   -c -o main.o main.c
main.c:9:22: error: graphics.h: No such file or directory
main.c: In function 'main':
main.c:50: error: 'Image' undeclared (first use in this function)
main.c:50: error: (Each undeclared identifier is reported only once
main.c:50: error: for each function it appears in.)
main.c:50: error: 'ourImage' undeclared (first use in this function)
main.c:53: warning: implicit declaration of function 'initGraphics'
main.c:55: warning: implicit declaration of function 'loadImage'
main.c:60: warning: implicit declaration of function 'blitAlphaImageToScreen'
main.c:61: warning: implicit declaration of function 'flipScreen'
make: *** [main.o] Error 1

[PSPJunkie_]

The quotes in the #include line tell the compiler that the header file is in the same directory as the current file.

So, if you have you main.c in 'blah/PSProjects/myProject/', graphics.c/h and framebuffer.c/h need to be in that directory as well.



I'm going to bed, so you may have to wait for yaustar if you are still having problems.

[Beat_Bob]

Ah thanks.
Also the warnings do I really need to be worried about them?
What could happen? (depending on the warnings)

[MiG]

Ah thanks.
Also the warnings do I really need to be worried about them?
What could happen? (depending on the warnings)

loads of things but your getting warnings because you have no idea what your doing, and missing a simple include.

Sorry, it seems i'm being a bit harsh, but make sure your code is word for word that of the tutorial.

[JaSo PsP]

main.c:9:22: error: graphics.h: No such file or directory

isnt it bloody obvious? It cant find 'graphics.h'! check that its actually there and check that you included it correctly.

[coolguy5678]

How can I install libpng for the compiler thingy built into CSP Development Studio?

Does anyone know?

[Auraomega]

Can someone point me in the direction of where I can find a tutorial or something on using sceIoAssign? I have some ideas I want to test out with it and flash... but needless to say, its flash and I want to make damn sure I can't mess up something!

Thanks.
-Aura

[adrahil]

Search on the PSP forum on http://forums.ps2dev.org . Don't post there or you'd get flamed instantly, though... :)

[PSPJunkie_]

Search on the PSP forum on http://forums.ps2dev.org . Don't post there or you'd get flamed instantly, though... :)

Yeah, adrahi's right. Regardless, ps2dev is the best. place. ever.