Using sdl2 I managed to construct "soon-to-be-spaghetti" classes for a game. However when it came to using a function of a class I stumble upon this weirdness.
class Player{
public:
Player();
const SDL_Rect *getPositionPtr() const { return &position; }
const SDL_Rect * getClip(){ return &clip; }
void eventHandle(SDL_Event & e);
void move();
private:
SDL_Rect position;
SDL_Rect clip;
float velocity;
bool leftkeydown;
bool rightkeydown;
};
Player::Player(){
position = {100, 300, 64, 64};
clip = {0, 0, 64, 64};
velocity = 0.3;
leftkeydown = false;
rightkeydown = false;
}
void Player::eventHandle(SDL_Event & e){
if( e.type == SDL_KEYDOWN && e.key.repeat == 0 ){
switch( e.key.keysym.sym ){
case SDLK_a:
leftkeydown = true;
break;
case SDLK_d:
rightkeydown = true;
break;
}
}
else if( e.type == SDL_KEYUP && e.key.repeat == 0 ){
//Adjust the velocity
switch( e.key.keysym.sym ){
case SDLK_a:
leftkeydown = false;
break;
case SDLK_d:
rightkeydown = false;
break;
}
}
}
void Player::move(){
if(leftkeydown) position.x -= velocity;
if(rightkeydown) position.x += velocity; // <----- problem here
}
leftkeydown seems to work as expected but rightkeydown doesn't do anything to the position.x variable.
Any ideas why it is not incrementing?
as #keltar commended it happens because at int + (float < 0) the int stays the same because it converts the result (100.3) from float to int (100) (thats because one of the values is int) so the position x will stay the same unless you make the velocity int or bigger than 0.
Related
I'm working on the motion for my paddles in my PONG clone and the program doesn't want to register SDL_KEYUP/DOWN sometimes. I think I have an idea of why this is but now how to fix it. So the way my game is looped currently I am using a state machine in my main() function that uses a Game class state which manages two paddles and a ball all of which are three different class instances. In side my Game class I run the events/logic/render from all three classes like so
void Game::events()
{
while (SDL_PollEvent(&event))
{
PlayerOne.events();
PlayerTwo.events();
Game_Ball.events();
}
}
void Game::logic()
{
PlayerOne.logic(delta.get_ticks());
PlayerTwo.logic(delta.get_ticks());
Game_Ball.logic();
}
void Game::render()
{
SDL_FillRect(screen, &screen->clip_rect, SDL_MapRGB(screen->format, 0, 0, 0));
PlayerOne.render();
PlayerTwo.render();
Game_Ball.render();
}
And the paddle class movement is managed like so (as fixed in the last question I had(:
void Paddle::events()
{
Uint8 *keystates = SDL_GetKeyState(NULL);
if (event.type == SDL_KEYDOWN)
{
if (player == 1)
{
if (keystates[SDLK_o] == 1)
{
yVel -= 100;
}
if (keystates[SDLK_k] == 1)
{
yVel += 100;
}
}
else
{
if (keystates[SDLK_w] == 1)
{
yVel -= 100;
}
if (keystates[SDLK_s] == 1)
{
yVel += 100;
}
}
}
if (event.type == SDL_KEYUP)
{
if (player == 1)
{
if (keystates[SDLK_o] == 0)
{
yVel += 100;
}
if (keystates[SDLK_k] == 0)
{
yVel -= 100;
}
}
else
{
if (keystates[SDLK_w] == 0)
{
yVel += 100;
}
if (keystates[SDLK_s] == 0)
{
yVel -= 100;
}
}
}
if (event.type == SDL_QUIT)
{
quit = true;
}
}
The problem here is that sometimes, if not most of the time, the keys don't react to move the player paddles up and down. but when they do it's less than half the time. I think this is because there is only a 1/3 chance that the program polls when a key is released or pressed, sometimes resulting in no change in the position. Basically, if PLAYERONE hits a key while Game is running PlayerTwo.events() it won't register the key press/release. Could this be a problem in the way I'm implementing the game loop in my main function?
int main(int argc, char* args[])
{
//init SDL
if (init() == false)
{
return 1;
}
//load everything
if (load_files() == false)
{
return 1;
}
delta.start();
currentState = new Game;
while (quit == false)
{
//handle state events
currentState->events();
// do state logic
currentState->logic();
//timer reset
delta.start();
//change state if needed
change_state();
//render state
currentState->render();
if (SDL_Flip(screen) == -1)
{
return 1;
}
}
clean_up();
return 0;
}
And here are the definitions and constructors
class Paddle
{
public:
int player;
SDL_Surface *sprite = NULL;
float x, y, w, h;
float yVel;
SDL_Rect *clip;
void events();
void logic(Uint32 deltaTicks);
void render();
Paddle();
~Paddle();
};
class Game : public GameState
{
private:
int server;
TTF_Font *score = NULL;
Paddle PlayerOne;
Paddle PlayerTwo;
Ball Game_Ball;
public:
SDL_Rect clip[2];
void events();
void logic();
void render();
Game();
~Game();
};
Game::Game()
{
//RESOURSES
PlayerOne.sprite = load_image("Game_sprite.png");
PlayerTwo.sprite = load_image("Game_sprite.png");
clip[0].x = 0;
clip[0].y = 0;
clip[0].w = 20;
clip[0].h = 20;
clip[1].x = 0;
clip[1].y = 20;
clip[1].w = 20;
clip[1].h = 100;
//PLAYER ONE
PlayerOne.x = 420;
PlayerOne.y = 100;
PlayerOne.w = 60;
PlayerOne.h = 100;
PlayerOne.clip = &clip[1];
PlayerOne.yVel = 0;
PlayerOne.player = 1;
//PLAYER TWO
PlayerTwo.x = 60;
PlayerTwo.y = 100;
PlayerTwo.w = 60;
PlayerTwo.h = 100;
PlayerTwo.clip = &clip[1];
PlayerTwo.yVel = 0;
PlayerTwo.player = 2;
//BALL
Game_Ball.Ball_Bound.x = 190;
Game_Ball.Ball_Bound.y = 190;
Game_Ball.Ball_Bound.w = 60;
Game_Ball.Ball_Bound.h = 60;
Game_Ball.clip = &clip[0];
}
Because that looks pretty clean to me. Other than another game loop implementation, what could I do to fix the keys not registering due to being in a different function? Or is it a loop implementation problem? If it is a loop problem, can you be through or include a reference as to how to fix it?
I don't see anything wrong in this code. However, the very possible cause might be simply limitation of how many keys are pressed on keyboard. Try using shift, ctrl and alt, keys for controls, they usually bypass the limitation.
I'm self learning programming using various online tutorials and a couple of books. Currently it's C++. I've done a bit of OpenGL and SDL in the last few days.
I have a small program that creates a wall to stop a small square from passing through it.
Here's my code:
//
// main.cpp
// SDL_Template
//
// The headers
#include <stdlib.h>
#include <string>
// SDL headers
#include <SDL/SDL.h>
#include "SDL_image/SDL_image.h"
//#include "SDL/SDL_ttf.h"
//#include "SDL/SDL_mixer.h"
// Other headers
#include <OpenGL/gl3.h>
// Screen attributes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;
// The frame rate
const int FRAMES_PER_SECOND = 20;
// The attributes of the square
const int SQUARE_WIDTH = 20;
const int SQUARE_HEIGHT = 20;
// The surfaces
SDL_Surface *square = NULL;
SDL_Surface *screen = NULL;
// The event structure
SDL_Event event;
// The wall
SDL_Rect wall;
// The square
class Square
{
private:
// The collision box of the square
SDL_Rect box;
// The velocity of the square
int xVel, yVel;
public:
// Initializes the variables
Square();
// Takes key presses and adjusts the square's velocity
void handle_input();
// Moves the square
void move();
// Shows the square on the screen
void show();
};
//The timer
class Timer
{
private:
// The clock time when the timer started
int startTicks;
// The ticks stored when the timer was paused
int pausedTicks;
// The timer status
bool paused;
bool started;
public:
// Initializes variables
Timer();
// The various clock actions
void start();
void stop();
void pause();
void unpause();
// Gets the timer's time
int get_ticks();
// Checks the status of the timer
bool is_started();
bool is_paused();
};
SDL_Surface *load_image(std::string filename)
{
// The image that's loaded
SDL_Surface* loadedImage = NULL;
// The optimized surface that will be used
SDL_Surface* optimizedImage = NULL;
// Load the image
loadedImage = IMG_Load(filename.c_str());
// If the image loaded
if (loadedImage != NULL)
{
// Create an optimized surface
optimizedImage = SDL_DisplayFormat(loadedImage);
// Free the old surface
SDL_FreeSurface(loadedImage);
// If the surface was optimized
if (optimizedImage != NULL)
{
// Color key surface
SDL_SetColorKey(optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB(optimizedImage->format, 0, 0xFF, 0xFF));
}
}
// Return the optimized surface
return optimizedImage;
}
void apply_surface(int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL)
{
// Holds offsets
SDL_Rect offset;
// Get offsets
offset.x = x;
offset.y = y;
// Blit
SDL_BlitSurface(source, clip, destination, &offset);
}
bool check_collision(SDL_Rect A, SDL_Rect B)
{
// The sides of the rectangles
int leftA, leftB;
int rightA, rightB;
int topA, topB;
int bottomA, bottomB;
// Calculate the sides of rect A
leftA = A.x;
rightA = A.x + A.w;
topA = A.y;
bottomA = A.y + A.h;
// Calculate the sides of rect B
leftB = B.x;
rightB = B.x + B.w;
topB = B.y;
bottomB = B.y + B.h;
// If any of the sides from A are outside of B
if( bottomA <= topB )
{
return false;
}
if( topA >= bottomB )
{
return false;
}
if( rightA <= leftB )
{
return false;
}
if( leftA >= rightB )
{
return false;
}
// If none of the sides from A are outside B
return true;
}
bool init()
{
// Initialize all SDL subsystems
if (SDL_Init( SDL_INIT_EVERYTHING ) == -1)
{
return false;
}
// Set up the screen
screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE);
// If there was an error in setting up the screen
if (screen == NULL)
{
return false;
}
// Set the window caption
SDL_WM_SetCaption("Move the Square", NULL);
// If everything initialized fine
return true;
}
bool load_files()
{
// Load the square image
square = load_image("square.bmp");
// If there was a problem in loading the square
if (square == NULL)
{
return false;
}
// If everything loaded fine
return true;
}
void clean_up()
{
// Free the surface
SDL_FreeSurface(square);
// Quit SDL
SDL_Quit();
}
Square::Square()
{
// Initialize the offsets
box.x = 0;
box.y = 0;
// Set the square's dimentions
box.w = SQUARE_WIDTH;
box.h = SQUARE_HEIGHT;
// Initialize the velocity
xVel = 0;
yVel = 0;
}
void Square::handle_input()
{
// If a key was pressed
if (event.type == SDL_KEYDOWN)
{
//Adjust the velocity
switch (event.key.keysym.sym)
{
case SDLK_UP: yVel -= SQUARE_HEIGHT / 2; break;
case SDLK_DOWN: yVel += SQUARE_HEIGHT / 2; break;
case SDLK_LEFT: xVel -= SQUARE_WIDTH / 2; break;
case SDLK_RIGHT: xVel += SQUARE_WIDTH / 2; break;
}
}
// If a key was released
else if (event.type == SDL_KEYUP)
{
//Adjust the velocity
switch (event.key.keysym.sym)
{
case SDLK_UP: yVel += SQUARE_HEIGHT / 2; break;
case SDLK_DOWN: yVel -= SQUARE_HEIGHT / 2; break;
case SDLK_LEFT: xVel += SQUARE_WIDTH / 2; break;
case SDLK_RIGHT: xVel -= SQUARE_WIDTH / 2; break;
}
}
}
void Square::move()
{
// Move the square left or right
box.x += xVel;
// If the square went too far to the left or right or has collided with the wall
if (( box.x < 0 ) || ( box.x + SQUARE_WIDTH > SCREEN_WIDTH ) || ( check_collision(box, wall)))
{
// Move back
box.x -= xVel;
}
// Move the square up or down
box.y += yVel;
// If the square went too far up or down or has collided with the wall
if (( box.y < 0 ) || ( box.y + SQUARE_HEIGHT > SCREEN_HEIGHT) || (check_collision(box, wall)))
{
// Move back
box.y -= yVel;
}
}
void Square::show()
{
// Show the square
apply_surface(box.x, box.y, square, screen);
}
Timer::Timer()
{
// Initialize the variables
startTicks = 0;
pausedTicks = 0;
paused = false;
started = false;
}
void Timer::start()
{
// Start the timer
started = true;
// Unpause the timer
paused = false;
// Get the current clock time
startTicks = SDL_GetTicks();
}
void Timer::stop()
{
// Stop the timer
started = false;
// Unpause the timer
paused = false;
}
void Timer::pause()
{
// If the timer is running and isn't already paused
if ((started == true) && (paused == false))
{
// Pause the timer
paused = true;
// Calculate the paused ticks
pausedTicks = SDL_GetTicks() - startTicks;
}
}
void Timer::unpause()
{
// If the timer is paused
if (paused == true)
{
// Unpause the timer
paused = false;
// Reset the starting ticks
startTicks = SDL_GetTicks() - pausedTicks;
// Reset the paused ticks
pausedTicks = 0;
}
}
int Timer::get_ticks()
{
// If the timer is running
if (started == true)
{
// If the timer is paused
if (paused == true)
{
// Return the number of ticks when the timer was paused
return pausedTicks;
}
else
{
// Return the current time minus the start time
return SDL_GetTicks() - startTicks;
}
}
// If the timer isn't running
return 0;
}
bool Timer::is_started()
{
return started;
}
bool Timer::is_paused()
{
return paused;
}
int main(int argc, char* args[])
{
// Quit flag
bool quit = false;
// The square
Square mySquare;
// The frame rate regulator
Timer fps;
// Initialize
if( init() == false )
{
return 1;
}
// Load the files
if (load_files() == false)
{
return 1;
}
// Set the wall
wall.x = 300;
wall.y = 40;
wall.w = 40;
wall.h = 400;
// While the user hasn't quit
while (quit == false)
{
// Start the frame timer
fps.start();
// While there are events to handle
while (SDL_PollEvent(&event))
{
// Handle events for the square
mySquare.handle_input();
// If the user has Xed out the window
if (event.type == SDL_QUIT)
{
// Quit the program
quit = true;
}
}
// Move the square
mySquare.move();
// Fill the screen white
SDL_FillRect(screen, &screen->clip_rect, SDL_MapRGB(screen->format, 0xFF, 0xFF, 0xFF));
// Show the wall
SDL_FillRect (screen, &wall, SDL_MapRGB(screen->format, 0x77, 0x77, 0x77));
// Show the square on the screen
mySquare.show();
// Update the screen
if (SDL_Flip(screen) == -1)
{
return 1;
}
// Cap the frame rate
if (fps.get_ticks() < 1000 / FRAMES_PER_SECOND)
{
SDL_Delay((1000 / FRAMES_PER_SECOND) - fps.get_ticks());
}
}
// Clean up
clean_up();
return 0;
}
I completely understand how this site works, so I'm not asking you to check my code. My code compiles in both Xcode 4.5 and Visual Studio 2010. In Xcode it compiles, but throws some warnings up (although it still builds), but nothing happens when it's run. However in Visual Studio 2012, it compiles, with no warnings and runs successfully.
I have searched here and the C++/SDL forums/help pages, but I haven't found any similar cases.
Why may this be? Seems it runs in Visual Studio 2010, I'm confident it isn't the code...
In case you were wondering the warnings flagged up in Xcode are:
229 enumeration values not handled in switch: 'SDLK_UNKNOWN','SDLK_BACKSPACE','SDLK_TAB'...
This is highlighted on the switch (event.key.keysym.sym) line of code.
So my questions are:
What kind of problems could case this warning error?
Are there any commonly know issues with programs working in Visual Studio and not Xcode?
I'm guessing (it seems I can't find anything about it) it's a setting somewhere that I haven't spotted...
I apologise for the length of this.
You are not handling all the possible choices in your switch statement. If this is what you intended then you can remove the warning by using the default case like the following:
switch (event.key.keysym.sym)
{
case SDLK_UP: yVel -= SQUARE_HEIGHT / 2; break;
case SDLK_DOWN: yVel += SQUARE_HEIGHT / 2; break;
case SDLK_LEFT: xVel -= SQUARE_WIDTH / 2; break;
case SDLK_RIGHT: xVel += SQUARE_WIDTH / 2; break;
default: break;
}
Xcode is simply warning you that you are not handling all possible values for the event.key.keysym.sym enumeration. Since I doubt you want to handle ever single different type of key press, this isn't a problem, as I would maybe see if I could turn down the warning level to suppress these warnings.
As for the program not running successfully when built by Xcode, I don't know. Perhaps SDL is set up in a different way?
I have a simple script where by i want the script to load a second button when the mouse is hovering over the first initial button. But it won't return true so i can't seem to get it to work.
This is my class which checks the situation:
class Button
{
private:
int m_x, m_y;
int m_width, m_height;
public:
Button(int x, int y, int width, int height)
{
m_x = x;
m_y = y;
m_width = width;
m_height = height;
}
bool IsIn( int mouseX, int mouseY )
{
if (((mouseX > m_x) && (mouseX < m_x + m_width))
&& ((mouseY > m_y) && (mouseY < m_y + m_height ) ) ) {
return true;
} else {
return false;
}
}
void Render(SDL_Surface *source,SDL_Surface *destination)
{
SDL_Rect offset;
offset.x = m_x;
offset.y = m_y;
offset.w = m_width;
offset.h = m_height;
source = IMG_Load("button.png");
SDL_BlitSurface( source, NULL, destination, &offset );
}
};
Its the IsIn function I am trying to get to work... in my main loop i have:
while(!quit){
while( SDL_PollEvent( &event ) )
switch( event.type ){
case SDL_QUIT: quit = true; break;
case SDL_MOUSEMOTION: mouseX = event.motion.x; mouseY = event.motion.y; break;
}
Button btn_quit(screen->w/2,screen->h/2,0,0);
btn_quit.Render(menu,screen);
if(btn_quit.IsIn(mouseX,mouseY)){
Button btn_settings(screen->w/2,screen->h/2+70,0,0);
btn_settings.Render(menu,screen);
}
SDL_Quit works fine but i can't seem to get the if statement after the case statement to return true when i hover the mouse over the btn_quit button. Any ideas why this might be ?
Because btn_quit has no width or height, and therefore you can never be inside it's bounds.
Button btn_quit(screen->w/2,screen->h/2,0,0);
You checks will fail because your mouse position can never be >x && <x+0 or >y && <y+0.
Perhaps a better way would be to define the location of your button, and let get the dimensions from the loaded image?
class Button
{
public:
// Construct the button with an image name, and position on screen.
// This is important, your existing code loaded the image each render.
// That is not necessary, load it once when you construct the class.
Button(std::string name, int x, int y) : img(IMG_Load(name))
{
if(img) // If the image didn't load, NULL is returned.
{
// Set the dimensions using the image width and height.
offset.x = x; offset.y = y;
offset.w = img.w; offset.h = img.h;
}
else { throw; } // Handle the fact that the image didn't load somehow.
}
~Button() { SDL_FreeSurface(img); } // Make sure you free your resources!
void Render(SDL_Surface *destination)
{
// Simplified render call.
SDL_BlitSurface(img, NULL, destination, &offset );
}
bool Contains(int x, int y)
{
if((x>offset.x) && (x<offset.x+offset.w)
&& (y>offset.y) && (y<offset.y+offset.h))
return true; // If your button contains this point.
return false; // Otherwise false.
}
private:
SDL_Rect offset; // Dimensions of the button.
SDL_Surface* img; // The button image.
}
I've been following LazyFoo's tutorial for a while. But I haven't been able to get this to initialize a week a go. I went back to it recently, after error checking, I found it that the window initializes properly, but the images won't load. What is the reason for it?
#include "SDL/SDL.h"
#include <string>
//setting screen info
const int SCH=640;
const int SCW=480;
const int BBP=32;
const char* name = "TEHGAEM";
// sprite height and width
const int SPH=45;
const int SPW=45;
//initilize event
SDL_Event event;
//loading surfaces for screen, sprite, and temp sprite
SDL_Surface *screen=NULL;
SDL_Surface *sprite=NULL;
SDL_Surface *temp = NULL;
//making class for movable objects
class Player
{
private:
int x,y;
int xVel,yVel;
public:
Player();
void show();
void move();
void handle_input();
};
//initializing variables
Player::Player()
{
x=0;
y=0;
xVel=0;
yVel=0;
}
//intended to show player picture
void Player::show()
{
SDL_Rect pos;
pos.x=x;
pos.y=y;
SDL_BlitSurface(sprite, NULL, screen, &pos);
SDL_UpdateRects(screen, 1, &pos);
}
//setting input
void Player::handle_input()
{
if (event.type ==SDL_KEYDOWN)
{
switch (event.key.keysym.sym)
{
case SDLK_UP: yVel -= SPH /2; break;
case SDLK_DOWN: yVel += SPH /2; break;
case SDLK_LEFT: xVel -=SPW /2; break;
case SDLK_RIGHT: xVel +=SPW /2; break;
}
}
if (event.type == SDL_KEYUP)
{
switch(event.key.keysym.sym)
{
case SDLK_UP: yVel += SPH /2; break;
case SDLK_DOWN: yVel -= SPH /2; break;
case SDLK_LEFT: xVel +=SPW /2; break;
case SDLK_RIGHT: xVel -=SPW /2; break;
}
}
}
void Player::move()
{
x=+xVel;
y=+yVel;
if (x >= SCW)
{
x-10;
}
if (y >= SCH)
{
y-10;
}
}
//initializing program
bool init()
{
if (SDL_Init(SDL_INIT_EVERYTHING)==-1)
{
return false;
}
screen = SDL_SetVideoMode(SCH,SCW,BBP, SDL_SWSURFACE);
if (screen == NULL)
{
return false;
}
SDL_WM_SetCaption(name, NULL);
return true;
}
//loading images
bool somethings()
{
temp = SDL_LoadBMP("sprite.bmp");
if (temp == NULL)
{
return false;
}
sprite = SDL_DisplayFormat (temp);
if (sprite ==NULL)
{
return false;
}
SDL_FreeSurface(temp);
return true;
}
//clean up function
void clean()
{
SDL_FreeSurface(sprite);
SDL_Quit();
}
int main(int argc, char* args[])
{
Player P1;
bool quit;
if (init() == false)
{
return 1;
}
if (somethings() ==false)
{
return 1;
}
while (quit ==false)
{
while (SDL_PollEvent(&event))
{
P1.handle_input();
if (event.type == SDL_QUIT)
{
quit == true;
}
}
if (SDL_Flip(screen) ==-1)
{
return 1;
}
P1.move();
P1.show();
}
clean();
return 0;
}
This isn't completely related to your problem but the varible bool quit; isn't defined as true or false before the main while( quit == false ) { ... }loop. This could produce undefined while loop behavior.
int main(int argc, char* args[])
{
Player P1;
bool quit = false; // CHANGE THIS AND SEE WHAT HAPPENS
if (init() == false)
{
return 1;
}
if (somethings() ==false)
{
return 1;
}
while (quit ==false)
{
while (SDL_PollEvent(&event))
{
P1.handle_input();
if (event.type == SDL_QUIT)
{
quit == true;
}
}
if (SDL_Flip(screen) ==-1)
{
return 1;
}
P1.move();
P1.show();
}
clean();
return 0;
}
About the images not loading, step through your program with a debugger and watch your somethings()function and follow the variables temp and sprite.
Make sure your "sprite.bmp" file is located in the running directory of this program. I tested it and it works for me.
Also this has no effect:
if (x >= SCW)
{
x-10;
}
if (y >= SCH)
{
y-10;
}
You probably wanted to say x -= 10; and y -= 10;.
This makes your 'player' jump back to the original position immediately:
if (event.type == SDL_KEYUP)
{
switch(event.key.keysym.sym)
{
case SDLK_UP: yVel += SPH /2; break;
case SDLK_DOWN: yVel -= SPH /2; break;
case SDLK_LEFT: xVel +=SPW /2; break;
case SDLK_RIGHT: xVel -=SPW /2; break;
}
}
You probably only need to handle SDL_KEYDOWN event.
Hope that helps.
There are big chances that you aren't loading the bitmap. But anything that you are trying to print on the screen and wasn't loaded can terminate the app.
I seem to be having the same trouble over and over again and cannot get my thick head around it. This program will not display a paddle as I want (and expected it) to do on screen :( -
#include <SDL/SDL.h>
#include <SDL/SDL_opengl.h>
SDL_Event event;
const int paddle_width = 20;
const int paddle_height = 80;
class PlayerPaddle
{
private:
int xloc;
int yloc;
int yvel;
public:
PlayerPaddle()
{
int xloc = 20;
int yloc = 200;
int yvel = 0;
}
void ShowPaddle()
{
glTranslatef(xloc,yloc,0);
glBegin(GL_QUADS);
glColor4f(1.0,1.0,1.0,1.0);
glVertex3f(0,0,0);
glVertex3f(20,0,0);
glVertex3f(20,80,0);
glVertex3f(0,80,0);
glEnd();
glLoadIdentity();
}
void MovePaddle()
{
yloc += yvel;
}
void Handle_Input()
{
if( event.type == SDL_KEYDOWN )
{
switch( event.key.keysym.sym )
{
case SDLK_UP: yvel -= paddle_height / 2; break;
case SDLK_DOWN: yvel += paddle_height / 2; break;
}
}
else if( event.type == SDL_KEYUP )
{
switch( event.key.keysym.sym )
{
case SDLK_UP: yvel += paddle_height / 2; break;
case SDLK_DOWN: yvel -= paddle_height / 2; break;
}
}
}
};
void init ()
{
SDL_Init(SDL_INIT_EVERYTHING);
SDL_SetVideoMode(640,480,32,SDL_OPENGL);
SDL_WM_SetCaption( "Pong", NULL );
glClearColor( 0, 0, 0, 0 );
glViewport(0, 0, 640, 480);
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glOrtho( 0, 640 , 480 , 0, 0, 1 );
glMatrixMode( GL_MODELVIEW );
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
}
int main (int argc, char **argv)
{
init();
PlayerPaddle ppaddle;
bool quit = false;
while (quit == false)
{
while (SDL_PollEvent (&event))
{
ppaddle.Handle_Input();
if (event.type == SDL_QUIT)
quit = true;
}
ppaddle.MovePaddle();
glClear(GL_COLOR_BUFFER_BIT);
ppaddle.ShowPaddle();
SDL_GL_SwapBuffers();
}
SDL_Quit();
return 0;
}
I just get a clear black screen until I quit the program which returns 0 as expected. I know the code:
ppaddle.MovePaddle();
glClear(GL_COLOR_BUFFER_BIT);
ppaddle.ShowPaddle();
SDL_GL_SwapBuffers();
iterates at least once as if I inserted a return 1; statement in there the program would start up and return 1 immediately.
At a minimum you screwed up your constructor. Again.
It should probably be this:
PlayerPaddle()
{
xloc = 20;
yloc = 200;
yvel = 0;
}
You may also want to toss in a SDL_Delay(100) at the end of your main loop to slow things down until you get some more sophisticated physics handling going.