Related
When I ran the following code, I expected a result where pressing one of three buttons would each trigger a matching state that would render a matching image adjacent to those buttons, allowing me to rotate through fresh images at leisure with each successive button press.
Instead of that happy scenario, any initial button press skips right to the last image...or does nothing...or renders a blank white screen depending on how I fiddle with my placement of the initial state declaration and whether I place the state switch within or without the event handling switch. The whole system breaks and stops dead in its tracks. What is going on, and how do I fix it?
#include <string>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include "cleanup.h"
SDL_Window* window = NULL;
SDL_Renderer* renderer = NULL;
SDL_Rect* clip = NULL;
const int LONGBUTTON_HEIGHT = 128;
const int LONGBUTTON_WIDTH = 256;
int Screen_Width = 640;
int Screen_Height = 480;
int mouse_x;
int mouse_y;
int alphabutton_x = 0;
int alphabutton_y = 5;
int alphabutton_h = Screen_Width / 10;
int alphabutton_w = Screen_Width / 5;
int betabutton_x = 0;
int betabutton_y = 0.5 * (Screen_Width / 5) + 5;
int betabutton_h = Screen_Width / 10;
int betabutton_w = Screen_Width / 5;
int gammabutton_x = 0;
int gammabutton_y = 1 * (Screen_Width / 5) + 5;
int gammabutton_h = Screen_Width / 10;
int gammabutton_w = Screen_Width / 5;
int alpha_x = Screen_Width / 5;
int alpha_y = 0;
int alpha_h = Screen_Height;
int alpha_w = (4* Screen_Width)/5;
int beta_x = Screen_Width / 5;
int beta_y = 0;
int beta_h = Screen_Height;
int beta_w = (4* Screen_Width)/5;
int gamma_x = Screen_Width / 5;
int gamma_y = 0;
int gamma_h = Screen_Height;
int gamma_w = (4* Screen_Width)/5;
enum alphaButtonSprite {ALPHA_DEFAULT, ALPHA_HOVER, ALPHA_INACTIVE, ALPHA_PRESSED, ALPHA_TOTAL};
enum betaButtonSprite {BETA_DEFAULT, BETA_HOVER, BETA_INACTIVE, BETA_PRESSED, BETA_TOTAL};
enum gammaButtonSprite {GAMMA_DEFAULT, GAMMA_HOVER, GAMMA_INACTIVE, GAMMA_PRESSED, GAMMA_TOTAL};
enum State {ALPHA_STATE, BETA_STATE, GAMMA_STATE};
State state;
SDL_Texture* loadTexture(const std::string& file, SDL_Renderer* renderer)
{
SDL_Texture* texture = IMG_LoadTexture(renderer, file.c_str());
return texture;
}
void renderTexture(SDL_Texture* texture, SDL_Renderer* renderer, SDL_Rect dest,
SDL_Rect* clip = nullptr)
{
SDL_RenderCopy(renderer, texture, clip, &dest);
}
void renderTexture(SDL_Texture* texture, SDL_Renderer* renderer, int x, int y, int h, int w,
SDL_Rect* clip = nullptr)
{
SDL_Rect dest;
dest.x = x;
dest.y = y;
dest.h = h;
dest.w = w;
renderTexture(texture, renderer, dest, clip);
}
// Main Function
int main(int, char**)
{
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("New Window", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, Screen_Width, Screen_Height, SDL_WINDOW_RESIZABLE);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
SDL_Texture* longbutton_image = loadTexture("longbuttonSpriteSheet.png", renderer);
SDL_Texture* alpha_image = loadTexture("alphaImage.png", renderer);
SDL_Texture* beta_image = loadTexture("betaImage.png", renderer);
SDL_Texture* gamma_image = loadTexture("gammaImage.png", renderer);
state = BETA_STATE;
SDL_Rect alpha_clips[alphaButtonSprite::ALPHA_TOTAL];
for (int i = 0; i < alphaButtonSprite::ALPHA_TOTAL; i++)
{
alpha_clips[i].x = i * LONGBUTTON_WIDTH;
alpha_clips[i].y = 0;
alpha_clips[i].w = LONGBUTTON_WIDTH;
alpha_clips[i].h = LONGBUTTON_HEIGHT;
}
int usealpha_Clip = ALPHA_DEFAULT;
SDL_Rect beta_clips[betaButtonSprite::BETA_TOTAL];
for (int i = 0; i < betaButtonSprite::BETA_TOTAL; i++)
{
beta_clips[i].x = i * LONGBUTTON_WIDTH;
beta_clips[i].y = 4 * LONGBUTTON_HEIGHT;
beta_clips[i].w = LONGBUTTON_WIDTH;
beta_clips[i].h = LONGBUTTON_HEIGHT;
}
int usebeta_Clip = BETA_DEFAULT;
SDL_Rect gamma_clips[gammaButtonSprite::GAMMA_TOTAL];
for (int i = 0; i < gammaButtonSprite::GAMMA_TOTAL; i++)
{
gamma_clips[i].x = i * LONGBUTTON_WIDTH;
gamma_clips[i].y = 5 * LONGBUTTON_HEIGHT;
gamma_clips[i].w = LONGBUTTON_WIDTH;
gamma_clips[i].h = LONGBUTTON_HEIGHT;
}
int usegamma_Clip = GAMMA_DEFAULT;
SDL_Event e;
bool quit = false;
while (!quit)
{
while (SDL_PollEvent(&e))
{
switch (e.type)
{
case SDL_MOUSEBUTTONDOWN:
mouse_x = e.button.x;
mouse_y = e.button.y;
if ((mouse_x <= (alphabutton_x + alphabutton_w)) && (mouse_x > alphabutton_x) &&
(mouse_y <= (alphabutton_y + alphabutton_h)) && (mouse_y > alphabutton_y))
usealpha_Clip = ALPHA_PRESSED;
state = ALPHA_STATE;
if ((mouse_x <= (betabutton_x + betabutton_w)) && (mouse_x > betabutton_x) &&
(mouse_y <= (betabutton_y + betabutton_h)) && (mouse_y > betabutton_y))
usebeta_Clip = BETA_PRESSED;
state = BETA_STATE;
if ((mouse_x <= (gammabutton_x + gammabutton_w)) && (mouse_x > gammabutton_x) &&
(mouse_y <= (gammabutton_y + gammabutton_h)) && (mouse_y > gammabutton_y))
usegamma_Clip = GAMMA_PRESSED;
state = GAMMA_STATE;
break;
}
}
switch (state)
{
case ALPHA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(alpha_image, renderer, alpha_x, alpha_y, alpha_h, alpha_w, nullptr);
SDL_RenderPresent(renderer);
break;
case BETA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(beta_image, renderer, beta_x, beta_y, beta_h, beta_w, nullptr);
SDL_RenderPresent(renderer);
break;
case GAMMA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(gamma_image, renderer, gamma_x, gamma_y, gamma_h, gamma_w, nullptr);
SDL_RenderPresent(renderer);
break;
}
}
//Destroy the various items
cleanup(longbutton_image, alpha_image, beta_image, gamma_image, renderer, window);
IMG_Quit();
SDL_Quit();
return 0;
}
Found the answer to this one. In the mousebuttondown event switch cases, just put the state code before the useclip code. Why it makes a difference, I don't know, but it works. Cough...Also, doing it in the mousebuttonup switch cases instead of mousebuttondown works even better.
My goal is to create an SDL window plotting different waveforms and playing an indefinite sound of this wave. By pressing specific keys, the parameters of the wave, like the amplitude, frequency or waveform can be modified.
The problem is that even a simple sine wave which looks nice when plotted, sounds noisy. I don't understand why.
Code:
#include "Graph.h"
#include <thread>
#include <iostream>
#include <sstream>
#include <string>
int main(int argc, char* argv[]){
Graph* g = new Graph();
int i;
std::cin >> i;
return 0;
}
int graphThreadFunc(void *pointer){
Graph* grid = (Graph*)pointer;
grid->init();
return 0;
}
// SDL calls this function whenever it wants its buffer to be filled with samples
void SDLAudioCallback(void *data, Uint8 *buffer, int length){
uint8_t *stream = (uint8_t*)buffer;
Graph* graph = (Graph*)data;
for (int i = 0; i <= length; i++){
if (graph->voice.audioLength <= 0)
stream[i] = graph->getSpec()->silence; // 128 is silence in a uint8 stream
else
{
stream[i] = graph->voice.getSample();
graph->voice.audioPosition++;
// Fill the graphBuffer with the first 1000 bytes of the wave for plotting
if (graph->graphPointer < 999)
graph->graphBuffer[graph->graphPointer++] = stream[i];
}
}
}
Graph::Graph()
{
// spawn thread
SDL_Thread *refresh_thread = SDL_CreateThread(graphThreadFunc, NULL, this);
}
SDL_AudioSpec* Graph::getSpec(){
return &this->spec;
}
void Graph::init()
{
// Init SDL & SDL_ttf
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER);
SDL_zero(desiredDeviceSpec);
desiredDeviceSpec.freq = 44100; // Sample Rate
desiredDeviceSpec.format = AUDIO_U8; // Unsigned 8-Bit Samples
desiredDeviceSpec.channels = 1; // Mono
desiredDeviceSpec.samples = 2048; // The size of the Audio Buffer (in number of samples, eg: 2048 * 1 Byte (AUDIO_U8)
desiredDeviceSpec.callback = SDLAudioCallback;
desiredDeviceSpec.userdata = this;
dev = SDL_OpenAudioDevice(NULL, 0, &desiredDeviceSpec, &spec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE);
if (dev == 0) {
printf("\nFailed to open audio: %s\n", SDL_GetError());
}
else {
SDL_PauseAudioDevice(dev, 1); /* pause! */
SDL_PauseAudio(1);
}
// Create an application window with the following settings:
window = SDL_CreateWindow(
WINDOW_TITLE.c_str(), // window title
SDL_WINDOWPOS_UNDEFINED, // initial x position
SDL_WINDOWPOS_UNDEFINED, // initial y position
WINDOW_WIDTH, // width, in pixels
WINDOW_HEIGHT, // height, in pixels
SDL_WINDOW_SHOWN // flags - see below
);
// Check if the window was successfully created
if (window == NULL) {
// In case the window could not be created...
printf("Could not create window: %s\n", SDL_GetError());
return;
}
else{
voice.waveForm = Graph::Voice::WaveForm::SINE;
voice.amp = 120;
voice.frequency = 440;
SDL_PauseAudioDevice(dev, 1); // play
graphPointer = 0;
voice.audioLength = 44100;
voice.audioPosition = 0;
SDL_PauseAudioDevice(dev, 0); // play
SDL_Delay(200);
drawGraph();
mainLoop();
return;
}
}
void Graph::mainLoop()
{
while (thread_exit == 0){
SDL_Event event;
bool hasChanged = false;
while (SDL_PollEvent(&event)) {
switch (event.type)
{
case SDL_KEYDOWN:
{
hasChanged = true;
if (event.key.keysym.scancode == SDL_SCANCODE_SPACE){
//pause_thread = !pause_thread;
switch (voice.waveForm){
case Voice::SINE:
{
voice.waveForm = Graph::Voice::WaveForm::TRIANGLE;
break;
}
case Voice::TRIANGLE:
{
voice.waveForm = Graph::Voice::WaveForm::RECT;
break;
}
case Voice::RECT:
{
voice.waveForm = Graph::Voice::WaveForm::SAWTOOTH;
break;
}
case Voice::SAWTOOTH:
{
voice.waveForm = Graph::Voice::WaveForm::SINE;
break;
}
default:
break;
}
}
else if (event.key.keysym.scancode == SDL_SCANCODE_ESCAPE){
exit();
}
else if (event.key.keysym.scancode == SDL_SCANCODE_RETURN){
}
else if (event.key.keysym.scancode == SDL_SCANCODE_LEFT){
voice.frequency -= 2;
}
else if (event.key.keysym.scancode == SDL_SCANCODE_RIGHT){
voice.frequency += 2;
}
else if (event.key.keysym.scancode == SDL_SCANCODE_UP){
voice.amp += 2;
}
else if (event.key.keysym.scancode == SDL_SCANCODE_DOWN){
voice.amp -= 2;
}
else{
}
break;
}
case SDL_QUIT:
{
exit();
return;
break;
}
default: /* unhandled event */
break;
}
}
if (!pause_thread && hasChanged)
{
//SDL_PauseAudioDevice(dev, 1); // play
graphPointer = 0;
voice.audioLength = 44100;
voice.audioPosition = 0;
SDL_PauseAudioDevice(dev, 0); // play
SDL_Delay(200);
drawGraph();
}
//voice.waveForm = Voice::WaveForm::TRIANGLE;
//SDL_Delay(n); // delay the program to prevent the voice to be overridden before it has been played to the end
//SDL_PauseAudioDevice(dev, 1); // pause
SDL_Delay(REFRESH_INTERVAL);
//SDL_PauseAudioDevice(dev, 1); // pause
}
return;
}
void Graph::drawGraph()
{
SDL_Renderer *renderer = SDL_GetRenderer(window);
if (renderer == nullptr)
renderer = SDL_CreateRenderer(window, 0, SDL_RENDERER_ACCELERATED);
// Set background color
SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);
// Clear winow
SDL_RenderClear(renderer);
SDL_SetRenderDrawColor(renderer, 22, 22, 22, 255);
for (int x = 0; x < WINDOW_WIDTH; x++){
uint8_t y = graphBuffer[x];
SDL_RenderDrawPoint(renderer, x, WINDOW_HEIGHT - y);
}
SDL_RenderPresent(renderer);
return;
}
void Graph::exit(){
thread_exit = 1;
// Close and destroy the window
SDL_DestroyWindow(window);
// Clean up
SDL_Quit();
}
uint8_t Graph::Voice::getSample(){
switch (waveForm){
case SINE:
{
float sineStep = 2 * M_PI * audioPosition * frequency / 44100;
return (amp * sin(sineStep)) + 128;
break;
}
case RECT:
break;
case SAWTOOTH:
break;
case TRIANGLE:
break;
default:
return 0;
}
}
And the header file:
#ifndef GRAPH_H
#define GRAPH_H
#include "SDL.h"
#include "SDL_audio.h"
#include <stdio.h>
#include <cmath>
#include <string>
#include <stack>
/* Constants */
const int REFRESH_INTERVAL = 50; // mseconds
const int WINDOW_WIDTH = 1000;
const int WINDOW_HEIGHT = 255;
const std::string WINDOW_TITLE = "Wave Graph";
class Graph
{
private:
SDL_Window *window; // Declare a pointer
// SDL audio stuff
SDL_AudioSpec desiredDeviceSpec;
SDL_AudioSpec spec;
SDL_AudioDeviceID dev;
int thread_exit = 0;
bool pause_thread = false;
public:
Graph();
void init();
void mainLoop();
void drawGraph();
void exit();
SDL_AudioSpec* getSpec();
struct Voice{
int frequency; // the frequency of the voice
int amp; // the amplitude of the voice
int audioLength; // number of samples to be played, eg: 1.2 seconds * 44100 samples per second
int audioPosition = 0; // counter
enum WaveForm{
SINE = 0, RECT = 1, SAWTOOTH = 2, TRIANGLE = 3
} waveForm;
uint8_t getSample();
} voice;
int graphPointer = 0;
uint8_t graphBuffer[1000];
};
#endif
Your SDLAudioCallback() is writing an extra byte off the end of buffer:
void SDLAudioCallback(void *data, Uint8 *buffer, int length)
{
...
for (int i = 0; i <= length; i++)
// ^^ huh?
{
...
}
}
Changing the <= to just < fixes the crackles on my system.
Generally C-style "byte pointer + length" APIs expect a left-closed, right-open interval: [0, length). I.e., you can access buffer[length - 1] but not buffer[length].
I'm wondering if anyone can point me in the right direction for this error.
I am learning 2D game programming using Allegro 5 installed in Visual Studio 2010.
I have been following a tutorial series and everything has been fine until the last lesson.
The final code will build successfully. The executable will load but will crash out when I hit the space bar to fire a bullet (it's a side shooter game). I get the following error:
"Assertion failed: spl, file allegro-git\addons\audio\kgm_sample.c line 321"
It obviously has something to do with the bullet sample sound linked in with the key press.
If I comment out the line: al_play_sample(shot, 1, 0, 1, ALLEGRO_PLAYMODE_ONCE, 0); in the FireBullet() function, then the game will play fine (without the bullet sound).
I have searched everywhere and cannot find a solution.
Here is the complete code for the game:
#include <allegro5\allegro.h>
#include <allegro5\allegro_primitives.h>
#include <allegro5\allegro_font.h>
#include <allegro5\allegro_ttf.h>
#include <allegro5\allegro_image.h>
#include <allegro5\allegro_audio.h>
#include <allegro5\allegro_acodec.h>
#include "objects.h"
//GLOBALS==============================
const int WIDTH = 800;
const int HEIGHT = 400;
const int NUM_BULLETS = 5;
const int NUM_COMETS = 10;
const int NUM_EXPLOSIONS = 5;
enum STATE{TITLE, PLAYING, LOST};
enum KEYS{UP, DOWN, LEFT, RIGHT, SPACE};
bool keys[5] = {false, false, false, false, false};
SpaceShip ship;
Bullet bullets[NUM_BULLETS];
Comet comets[NUM_COMETS];
Explosion explosions[NUM_EXPLOSIONS];
ALLEGRO_SAMPLE *shot = NULL;
ALLEGRO_SAMPLE *boom = NULL;
ALLEGRO_SAMPLE *song = NULL;
ALLEGRO_SAMPLE_INSTANCE *songInstance = NULL;
//prototypes
void InitShip(SpaceShip &ship, ALLEGRO_BITMAP *image);
void ResetShipAnimation(SpaceShip &ship, int position);
void DrawShip(SpaceShip &ship);
void MoveShipUp(SpaceShip &ship);
void MoveShipDown(SpaceShip &ship);
void MoveShipLeft(SpaceShip &ship);
void MoveShipRight(SpaceShip &ship);
void InitBullet(Bullet bullet[], int size);
void DrawBullet(Bullet bullet[], int size);
void FireBullet(Bullet bullet[], int size, SpaceShip &ship);
void UpdateBullet(Bullet bullet[], int size);
void CollideBullet(Bullet bullet[], int bSize, Comet comets[], int cSize, SpaceShip &ship, Explosion explosions[], int eSize);
void InitComet(Comet comets[], int size, ALLEGRO_BITMAP *image);
void DrawComet(Comet comets[], int size);
void StartComet(Comet comets[], int size);
void UpdateComet(Comet comets[], int size);
void CollideComet(Comet comets[], int cSize, SpaceShip &ship, Explosion explosions[], int eSize);
void InitExplosions(Explosion explosions[], int size, ALLEGRO_BITMAP *image);
void DrawExplosions(Explosion explosions[], int size);
void StartExplosions(Explosion explosions[], int size, int x, int y);
void UpdateExplosions(Explosion explosions[], int size);
void InitBackground(Background &back, float x, float y, float velX, float velY, int width, int height, int dirX, int dirY, ALLEGRO_BITMAP *image);
void UpdateBackground(Background &back);
void DrawBackground(Background &back);
void ChangeState(int &state, int newState);
int main(void)
{
//primitive variable
bool done = false;
bool redraw = true;
const int FPS = 60;
int state = -1;
//object variables
Background BG;
Background MG;
Background FG;
//Allegro variables
ALLEGRO_DISPLAY *display = NULL;
ALLEGRO_EVENT_QUEUE *event_queue = NULL;
ALLEGRO_TIMER *timer = NULL;
ALLEGRO_FONT *font18 = NULL;
ALLEGRO_BITMAP *shipImage;
ALLEGRO_BITMAP *cometImage;
ALLEGRO_BITMAP *expImage;
ALLEGRO_BITMAP *title = NULL;
ALLEGRO_BITMAP *lost = NULL;
ALLEGRO_BITMAP *bgImage = NULL;
ALLEGRO_BITMAP *mgImage = NULL;
ALLEGRO_BITMAP *fgImage = NULL;
//Initialization Functions
if(!al_init()) //initialize Allegro
return -1;
display = al_create_display(WIDTH, HEIGHT); //create our display object
if(!display) //test display object
return -1;
al_init_primitives_addon();
al_install_keyboard();
al_init_font_addon();
al_init_ttf_addon();
al_init_image_addon();
al_install_audio();
al_init_acodec_addon();
event_queue = al_create_event_queue();
timer = al_create_timer(1.0 / FPS);
shipImage = al_load_bitmap("spaceship_by_arboris.png");
al_convert_mask_to_alpha(shipImage, al_map_rgb(255, 0, 255));
cometImage = al_load_bitmap("asteroids.png");
expImage = al_load_bitmap("explosion.png");
title = al_load_bitmap("Shooter_Title.png");
lost = al_load_bitmap("Shooter_Lose.png");
bgImage = al_load_bitmap("starBG.png");
mgImage = al_load_bitmap("starMG.png");
fgImage = al_load_bitmap("starFG.png");
al_reserve_samples(10);
shot = al_load_sample("shot.ogg");
boom = al_load_sample("explosion.wav");
song = al_load_sample("war.wav");
songInstance = al_create_sample_instance(song);
al_set_sample_instance_playmode(songInstance, ALLEGRO_PLAYMODE_LOOP);
al_attach_sample_instance_to_mixer(songInstance, al_get_default_mixer());
srand(time(NULL));
ChangeState(state, TITLE);
InitShip(ship, shipImage);
InitBullet(bullets, NUM_BULLETS);
InitComet(comets, NUM_COMETS, cometImage);
InitExplosions(explosions, NUM_EXPLOSIONS, expImage);
InitBackground(BG, 0, 0, 1, 0, 800, 400, -1, 1, bgImage);
InitBackground(MG, 0, 0, 2, 0, 2400, 400, -1, 1, mgImage);
InitBackground(FG, 0, 0, 4, 0, 2400, 400, -1, 1, fgImage);
font18 = al_load_font("arial.ttf", 18, 0);
al_register_event_source(event_queue, al_get_keyboard_event_source());
al_register_event_source(event_queue, al_get_timer_event_source(timer));
al_register_event_source(event_queue, al_get_display_event_source(display));
al_start_timer(timer);
while(!done)
{
ALLEGRO_EVENT ev;
al_wait_for_event(event_queue, &ev);
if(ev.type == ALLEGRO_EVENT_TIMER)
{
redraw = true;
if(keys[UP])
MoveShipUp(ship);
else if(keys[DOWN])
MoveShipDown(ship);
else
ResetShipAnimation(ship, 1);
if(keys[LEFT])
MoveShipLeft(ship);
else if(keys[RIGHT])
MoveShipRight(ship);
else
ResetShipAnimation(ship, 2);
if(state == TITLE)
{}
else if(state == PLAYING)
{
UpdateBackground(BG);
UpdateBackground(MG);
UpdateBackground(FG);
UpdateExplosions(explosions, NUM_EXPLOSIONS);
UpdateBullet(bullets, NUM_BULLETS);
StartComet(comets, NUM_COMETS);
UpdateComet(comets, NUM_COMETS);
CollideBullet(bullets, NUM_BULLETS, comets, NUM_COMETS, ship, explosions, NUM_EXPLOSIONS);
CollideComet(comets, NUM_COMETS, ship, explosions, NUM_EXPLOSIONS);
if(ship.lives <= 0)
ChangeState(state, LOST);
}
else if(state == LOST)
{}
}
else if(ev.type == ALLEGRO_EVENT_DISPLAY_CLOSE)
{
done = true;
}
else if(ev.type == ALLEGRO_EVENT_KEY_DOWN)
{
switch(ev.keyboard.keycode)
{
case ALLEGRO_KEY_ESCAPE:
done = true;
break;
case ALLEGRO_KEY_UP:
keys[UP] = true;
break;
case ALLEGRO_KEY_DOWN:
keys[DOWN] = true;
break;
case ALLEGRO_KEY_LEFT:
keys[LEFT] = true;
break;
case ALLEGRO_KEY_RIGHT:
keys[RIGHT] = true;
break;
case ALLEGRO_KEY_SPACE:
keys[SPACE] = true;
if(state == TITLE)
ChangeState(state, PLAYING);
else if(state ==PLAYING)
FireBullet(bullets, NUM_BULLETS, ship);
else if(state == LOST)
ChangeState(state, PLAYING);
break;
}
}
else if(ev.type == ALLEGRO_EVENT_KEY_UP)
{
switch(ev.keyboard.keycode)
{
case ALLEGRO_KEY_ESCAPE:
done = true;
break;
case ALLEGRO_KEY_UP:
keys[UP] = false;
break;
case ALLEGRO_KEY_DOWN:
keys[DOWN] = false;
break;
case ALLEGRO_KEY_LEFT:
keys[LEFT] = false;
break;
case ALLEGRO_KEY_RIGHT:
keys[RIGHT] = false;
break;
case ALLEGRO_KEY_SPACE:
keys[SPACE] = false;
break;
}
}
if(redraw && al_is_event_queue_empty(event_queue))
{
redraw = false;
if(state == TITLE)
{
al_draw_bitmap(title, 0, 0, 0);
}
else if(state == PLAYING)
{
DrawBackground(BG);
DrawBackground(MG);
DrawBackground(FG);
DrawShip(ship);
DrawBullet(bullets, NUM_BULLETS);
DrawComet(comets, NUM_COMETS);
DrawExplosions(explosions, NUM_EXPLOSIONS);
al_draw_textf(font18, al_map_rgb(255, 0, 255), 5, 5, 0, "Player has %i lives left. Player has destroyed %i objects", ship.lives, ship.score);
}
else if(state == LOST)
{
al_draw_bitmap(lost, 0, 0, 0);
al_draw_textf(font18, al_map_rgb(0, 255, 255), WIDTH - 10, 20, ALLEGRO_ALIGN_RIGHT, "Final Score: %i", ship.score);
}
al_flip_display();
al_clear_to_color(al_map_rgb(0,0,0));
}
}
al_destroy_sample(shot);
al_destroy_sample(boom);
al_destroy_sample(song);
al_destroy_sample_instance(songInstance);
al_destroy_bitmap(bgImage);
al_destroy_bitmap(mgImage);
al_destroy_bitmap(fgImage);
al_destroy_bitmap(title);
al_destroy_bitmap(lost);
al_destroy_bitmap(expImage);
al_destroy_bitmap(cometImage);
al_destroy_bitmap(shipImage);
al_destroy_event_queue(event_queue);
al_destroy_timer(timer);
al_destroy_font(font18);
al_destroy_display(display); //destroy our display object
return 0;
}
void InitShip(SpaceShip &ship, ALLEGRO_BITMAP *image = NULL) {
ship.x = 20;
ship.y = HEIGHT / 2;
ship.ID = PLAYER;
ship.lives = 3;
ship.speed = 6;
ship.boundx = 10;
ship.boundy = 12;
ship.score = 0;
ship.maxFrame = 3;
ship.curFrame = 0;
ship.frameCount = 0;
ship.frameDelay = 50;
ship.frameWidth = 44;
ship.frameHeight = 41;
ship.animationColumns = 3;
ship.animationDirection = 1;
ship.animationRow = 1;
if(image != NULL)
ship.image = image;
}
void ResetShipAnimation(SpaceShip &ship, int position)
{
if(position == 1)
ship.animationRow = 1;
else
ship.curFrame = 0;
}
void DrawShip(SpaceShip &ship)
{
int fx =(ship.curFrame % ship.animationColumns) * ship.frameWidth;
int fy = ship.animationRow * ship.frameHeight;
al_draw_bitmap_region(ship.image, fx, fy, ship.frameWidth,
ship.frameHeight, ship.x - ship.frameWidth / 2, ship.y - ship.frameHeight / 2, 0);
/*al_draw_filled_rectangle(ship.x - ship.boundx, ship.y - ship.boundy, ship.x + ship.boundx,
ship.y + ship.boundy, al_map_rgba(255, 0, 255, 100));*/
}
void MoveShipUp(SpaceShip &ship)
{
ship.animationRow = 0;
ship.y -= ship.speed;
if(ship.y < 0)
ship.y = 0;
}
void MoveShipDown(SpaceShip &ship)
{
ship.animationRow = 2;
ship.y += ship.speed;
if(ship.y > HEIGHT)
ship.y = HEIGHT;
}
void MoveShipLeft(SpaceShip &ship)
{
ship.curFrame = 2;
ship.x -= ship.speed;
if(ship.x < 0)
ship.x = 0;
}
void MoveShipRight(SpaceShip &ship)
{
ship.curFrame = 1;
ship.x += ship.speed;
if(ship.x > 300)
ship.x = 300;
}
void InitBullet(Bullet bullet[], int size)
{
for(int i = 0; i < size; i++)
{
bullet[i].ID = BULLET;
bullet[i].speed = 10;
bullet[i].live = false;
}
}
void DrawBullet(Bullet bullet[], int size)
{
for( int i = 0; i < size; i++)
{
if(bullet[i].live)
al_draw_filled_circle(bullet[i].x, bullet[i].y, 2, al_map_rgb(255, 255, 255));
}
}
void FireBullet(Bullet bullet[], int size, SpaceShip &ship)
{
for( int i = 0; i < size; i++)
{
if(!bullet[i].live)
{
bullet[i].x = ship.x + 17;
bullet[i].y = ship.y;
bullet[i].live = true;
al_play_sample(shot, 1, 0, 1, ALLEGRO_PLAYMODE_ONCE, 0);
break;
}
}
}
void UpdateBullet(Bullet bullet[], int size)
{
for(int i = 0; i < size; i++)
{
if(bullet[i].live)
{
bullet[i].x += bullet[i].speed;
if(bullet[i].x > WIDTH)
bullet[i].live = false;
}
}
}
void CollideBullet(Bullet bullet[], int bSize, Comet comets[], int cSize, SpaceShip &ship, Explosion explosions[], int eSize)
{
for(int i = 0; i < bSize; i++)
{
if(bullet[i].live)
{
for(int j =0; j < cSize; j++)
{
if(comets[j].live)
{
if(bullet[i].x > (comets[j].x - comets[j].boundx) &&
bullet[i].x < (comets[j].x + comets[j].boundx) &&
bullet[i].y > (comets[j].y - comets[j].boundy) &&
bullet[i].y < (comets[j].y + comets[j].boundy))
{
bullet[i].live = false;
comets[j].live = false;
ship.score++;
StartExplosions(explosions, eSize, bullet[i].x, bullet[i].y);
al_play_sample(boom, 1, 0, 1, ALLEGRO_PLAYMODE_ONCE, 0);
}
}
}
}
}
}
void InitComet(Comet comets[], int size, ALLEGRO_BITMAP *image = NULL)
{
for(int i = 0; i < size; i++)
{
comets[i].ID = ENEMY;
comets[i].live = false;
comets[i].speed = 5;
comets[i].boundx = 35;
comets[i].boundy = 35;
comets[i].maxFrame = 143;
comets[i].curFrame = 0;
comets[i].frameCount = 0;
comets[i].frameDelay = 2;
comets[i].frameWidth = 96;
comets[i].frameHeight = 96;
comets[i].animationColumns = 21;
if(rand() % 2)
comets[i].animationDirection = 1;
else
comets[i].animationDirection = -1;
if(image != NULL)
comets[i].image = image;
}
}
void DrawComet(Comet comets[], int size)
{
for(int i = 0; i < size; i++)
{
if(comets[i].live)
{
int fx = (comets[i].curFrame % comets[i].animationColumns) * comets[i].frameWidth;
int fy = (comets[i].curFrame / comets[i].animationColumns) * comets[i].frameHeight;
al_draw_bitmap_region(comets[i].image, fx, fy, comets[i].frameWidth,
comets[i].frameHeight, comets[i].x - comets[i].frameWidth / 2, comets[i].y - comets[i].frameHeight / 2, 0);
/*al_draw_filled_rectangle(comets[i].x - comets[i].boundx, comets[i].y - comets[i].boundy, comets[i].x + comets[i].boundx,
comets[i].y + comets[i].boundy, al_map_rgba(255, 0, 255, 100));*/
}
}
}
void StartComet(Comet comets[], int size)
{
for(int i = 0; i < size; i++)
{
if(!comets[i].live)
{
if(rand() % 500 == 0)
{
comets[i].live = true;
comets[i].x = WIDTH;
comets[i].y = 30 + rand() % (HEIGHT - 60);
break;
}
}
}
}
void UpdateComet(Comet comets[], int size)
{
for(int i = 0; i < size; i++)
{
if(comets[i].live)
{
if(++comets[i].frameCount >= comets[i].frameDelay)
{
comets[i].curFrame += comets[i].animationDirection;
if(comets[i].curFrame >= comets[i].maxFrame)
comets[i].curFrame = 0;
else if( comets[i].curFrame <= 0)
comets[i].curFrame = comets[i].maxFrame - 1;
comets[i].frameCount = 0;
}
comets[i].x -= comets[i].speed;
}
}
}
void CollideComet(Comet comets[], int cSize, SpaceShip &ship, Explosion explosions[], int eSize)
{
for(int i = 0; i < cSize; i++)
{
if(comets[i].live)
{
if(comets[i].x - comets[i].boundx < ship.x + ship.boundx &&
comets[i].x + comets[i].boundx > ship.x - ship.boundx &&
comets[i].y - comets[i].boundy < ship.y + ship.boundy &&
comets[i].y + comets[i].boundy > ship.y - ship.boundy)
{
ship.lives--;
comets[i].live = false;
StartExplosions(explosions, eSize, ship.x, ship.y);
al_play_sample(boom, 1, 0, 1, ALLEGRO_PLAYMODE_ONCE, 0);
}
else if(comets[i].x < 0)
{
comets[i].live = false;
ship.lives--;
}
}
}
}
void InitExplosions(Explosion explosions[], int size, ALLEGRO_BITMAP *image = NULL)
{
for(int i = 0; i < size; i++)
{
explosions[i].live = false;
explosions[i].maxFrame = 31;
explosions[i].curFrame = 0;
explosions[i].frameCount = 0;
explosions[i].frameDelay = 1;
explosions[i].frameWidth = 128;
explosions[i].frameHeight = 128;
explosions[i].animationColumns = 8;
explosions[i].animationDirection = 1;
if(image != NULL)
explosions[i].image = image;
}
}
void DrawExplosions(Explosion explosions[], int size)
{
for(int i = 0; i < size; i++)
{
if(explosions[i].live)
{
int fx = (explosions[i].curFrame % explosions[i].animationColumns) * explosions[i].frameWidth;
int fy = (explosions[i].curFrame / explosions[i].animationColumns) * explosions[i].frameHeight;
al_draw_bitmap_region(explosions[i].image, fx, fy, explosions[i].frameWidth,
explosions[i].frameHeight, explosions[i].x - explosions[i].frameWidth / 2, explosions[i].y - explosions[i].frameHeight / 2, 0);
}
}
}
void StartExplosions(Explosion explosions[], int size, int x, int y)
{
for(int i = 0; i < size; i++)
{
if(!explosions[i].live)
{
explosions[i].live = true;
explosions[i].x = x;
explosions[i].y = y;
break;
}
}
}
void UpdateExplosions(Explosion explosions[], int size)
{
for(int i = 0; i < size; i++)
{
if(explosions[i].live)
{
if(++explosions[i].frameCount >= explosions[i].frameDelay)
{
explosions[i].curFrame += explosions[i].animationDirection;
if(explosions[i].curFrame >= explosions[i].maxFrame)
{
explosions[i].curFrame = 0;
explosions[i].live = false;
}
explosions[i].frameCount = 0;
}
}
}
}
void InitBackground(Background &back, float x, float y, float velx, float vely, int width, int height, int dirX, int dirY, ALLEGRO_BITMAP *image)
{
back.x = x;
back.y = y;
back.velX = velx;
back.velY = vely;
back.width = width;
back.height = height;
back.dirX = dirX;
back.dirY = dirY;
back.image = image;
}
void UpdateBackground(Background &back)
{
back.x += back.velX * back.dirX;
if(back.x + back.width <= 0)
back.x = 0;
}
void DrawBackground(Background &back)
{
al_draw_bitmap(back.image, back.x, back.y, 0);
if(back.x + back.width < WIDTH)
al_draw_bitmap(back.image, back.x + back.width, back.y, 0);
}
void ChangeState(int &state, int newState)
{
if(state == TITLE)
{}
else if(state == PLAYING)
{
al_stop_sample_instance(songInstance);
}
else if(state == LOST)
{}
state = newState;
if(state == TITLE)
{}
else if(state == PLAYING)
{
InitShip(ship);
InitBullet(bullets, NUM_BULLETS);
InitComet(comets, NUM_COMETS);
InitExplosions(explosions, NUM_EXPLOSIONS);
al_play_sample_instance(songInstance);
}
else if(state == LOST)
{}
}
Check that a pointer you are using is not NULL when you try to load the file. If it stays NULL then that exception is always thrown because the system will try to read from memory address 0x0 which frankly does not exist
I am attempting to make a simple scrolling shooter game with SDL2. I have a moving player on a screen, and I am trying to make the player shoot a bullet using an array (so they can shoot multiple bullets) however, when I press the space bar, nothing happens, and instead the bullet image sort of flashes in the top left corner.
Heres the same code in codepad: http://codepad.org/rOhE1AqY
#include <SDL.h>
#include <stdio.h> //use for things like printf, same as cout
#include <iostream>
#include <string>
#include <time.h>
using namespace std;
//screend dimensions& sprtie dimensions
const int SCREEN_HEIGHT = 600;
const int SCREEN_WIDTH = 400;
const int SPRITE_WIDTH = 60;
const int SPRITE_HEIGHT = 80;
const int MAX_BULLETS = 50;
SDL_Window* Window = NULL;//the window rendering to
SDL_Surface* ScreenSurface = NULL;//surface contained by window
SDL_Surface* Background = NULL;
SDL_Surface* Player = NULL;
SDL_Surface* Enemy = NULL;
SDL_Surface* Bullet = NULL;
SDL_Surface* newBullet = NULL;
SDL_Rect posPlayer, posEnemy, posBullet, posnewBullet;
const Uint8* keystate = SDL_GetKeyboardState(NULL);
SDL_Event event;
class thePlayer
{
public:
thePlayer();
void player_movement();
void show_player();
private:
};
class theBullet
{
public:
theBullet();
bool isActive;
int x_position;
int y_position;
void bullet_movement();
void add_new_bullet();
void show_bullet();
private:
};
theBullet arrayofBullets[MAX_BULLETS];
class theEnemy
{
public:
theEnemy();
void enemy_movement();
void show_enemy();
private:
};
thePlayer::thePlayer()
{
posPlayer.x = 170;
posPlayer.y = SCREEN_HEIGHT;
posPlayer.w = 20;
posPlayer.h = 30;
}
void thePlayer::player_movement()
{
if(keystate[SDL_SCANCODE_LEFT])
{
posPlayer.x -= 2;
}
if(keystate[SDL_SCANCODE_RIGHT])
{
posPlayer.x += 2;
}
if(keystate[SDL_SCANCODE_UP])
{
posPlayer.y -= 2;
}
if(keystate[SDL_SCANCODE_DOWN])
{
posPlayer.y += 2;
}
if ((posPlayer.x + SPRITE_WIDTH) > SCREEN_WIDTH)
{
posPlayer.x = (SCREEN_WIDTH - SPRITE_WIDTH);
}
if ((posPlayer.y + SPRITE_HEIGHT) > SCREEN_HEIGHT)
{
posPlayer.y = (SCREEN_HEIGHT - SPRITE_HEIGHT);
}
}
void thePlayer::show_player()
{
SDL_BlitSurface(Player, NULL, ScreenSurface, &posPlayer);
SDL_SetColorKey(Player, SDL_TRUE, SDL_MapRGB(Player->format, 255, 255, 255));
}
theBullet::theBullet()
{
/*posBullet.x;
posBullet.y;
posBullet.w = 10;
posBullet.h = 15;*/
}
void theBullet::bullet_movement()
{
/*if(keystate[SDL_SCANCODE_SPACE])
{
posBullet.x = posPlayer.x + 25;
posBullet.y = posPlayer.y + 10;
}
posBullet.y -= 2;
if(posBullet.y < 0)
{
posBullet.y = -50;
}*/
}
void theBullet::show_bullet()
{
//SDL_BlitSurface(Bullet, NULL, ScreenSurface, &posBullet);
//SDL_SetColorKey(Bullet, SDL_TRUE, SDL_MapRGB(Player->format, 255, 255, 255));//removes white background
}
theEnemy::theEnemy()
{
srand (time(NULL));
posEnemy.x = rand() % 300 + 50;
posEnemy.y =0;
posEnemy.w = 35;
posEnemy.h = 60;
}
void theEnemy::enemy_movement()
{
posEnemy.y += 1;
if(posEnemy.y > SCREEN_HEIGHT)
{
posEnemy.y = SCREEN_HEIGHT +50;
}
}
void theEnemy::show_enemy()
{
SDL_BlitSurface(Enemy, NULL, ScreenSurface, &posEnemy);
SDL_SetColorKey(Enemy, SDL_TRUE, SDL_MapRGB(Player->format, 255, 255, 255));
}
bool initialise()
{
bool success = true;
if (SDL_Init(SDL_INIT_EVERYTHING) !=0)
{
cout<<"SDL_Init Error."<<SDL_GetError()<<endl;
success = false;
}
else
{
//create the window for game
Window = SDL_CreateWindow("Scrolling Shooter Game", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
if (Window == NULL)
{
cout<<"Window Error"<<SDL_GetError()<<endl;
success = false;
}
else
{
//get window surface
ScreenSurface = SDL_GetWindowSurface(Window);
}
}
return success;
}
bool LoadingMedia()
{
bool success = true;
Background = SDL_LoadBMP("background.bmp");
if (Background == NULL)
{
cout<<"Error in loading background."<<SDL_GetError()<<endl;
success = false;
}
Player = SDL_LoadBMP("spaceship.bmp");
if (Player == NULL)
{
cout<<"Error in loading player."<<SDL_GetError()<<endl;
success = false;
}
Enemy = SDL_LoadBMP("enemy.bmp");
if (Enemy == NULL)
{
cout<<"Error in loading enemy."<<SDL_GetError()<<endl;
success = false;
}
Bullet = SDL_LoadBMP("bullet.bmp");
if (Bullet == NULL)
{
cout<<"Error in loading bullet."<<SDL_GetError()<<endl;
success = false;
}
return success;
}
void closedown()
{
SDL_FreeSurface(Background);
Background = NULL;
SDL_FreeSurface(Player);
Player = NULL;
SDL_FreeSurface(Enemy);
Enemy = NULL;
SDL_DestroyWindow(Window);
Window = NULL;
SDL_Quit();
}
int main(int argc, char** argv)
{
bool quit = false;
thePlayer myPlayer;
theEnemy myEnemy;
theBullet myBullet;
if (!initialise())
{
cout<<"Failed to initialise"<<SDL_GetError()<<endl;
}
else
{
if (!LoadingMedia())
{
cout<<"Error loading media"<<SDL_GetError()<<endl;
}
}
//makes all bullets false
for (int i=0; i<MAX_BULLETS; i++)
{
arrayofBullets[i].isActive = false;
}
//GAME LOOP
while (quit == false)
{
SDL_BlitSurface(Background, NULL, ScreenSurface, NULL);
myPlayer.show_player();
myPlayer.player_movement();
while (SDL_PollEvent(&event))
{
if( event.type == SDL_QUIT )
{
quit = true;
break;
}
if(keystate[SDL_SCANCODE_SPACE])
{
for (int i=0; i<MAX_BULLETS; i++)
{
if (arrayofBullets[i].isActive == false)
{
arrayofBullets[i].x_position = posPlayer.x + 25;
arrayofBullets[i].y_position = posPlayer.y + 10;
arrayofBullets[i].isActive = true;
break;
}
}
}
//update game objects
for (int i=0; i<MAX_BULLETS; i++)
{
if (arrayofBullets[i].isActive == true)
{
arrayofBullets[i].y_position -= 2;
if (arrayofBullets[i].y_position < 0)
{
arrayofBullets[i].isActive = false;
}
}
}
for (int i=0; i<MAX_BULLETS; i++)
{
if (arrayofBullets[i].isActive == true)
{
SDL_BlitSurface(Bullet, NULL, ScreenSurface, NULL);
}
}
}
//myPlayer.show_player();
//myBullet.show_bullet();
//myEnemy.show_enemy();
//myPlayer.player_movement();
//myBullet.bullet_movement();
//myEnemy.enemy_movement();
SDL_UpdateWindowSurface(Window); //updates screen
}
closedown();
return 0;
}
SDL_BlitSurface(Bullet, NULL, ScreenSurface, NULL);
You haven't specified destination rect, so it will blit on left-top corner.
It should be
SDL_Rect dstrect;
dstrect.x = arrayofBullets[i].x_position;
dstrect.y = arrayofBullets[i].y_position;
dstrect.w = Bullet->w;
dstrect.h = Bullet->h;
SDL_BlitSurface(Bullet, NULL, ScreenSurface, &dstrect);
I have a bmp-file of numbers and characters. My program reads keypresses and blits the appropriate character/number from the bitmap onto the screen. The only problem is if i press 'A' - 'A' will show on screen, but if I press 'B', it will take 'A's place. So I will never have more than one character on screen.
Here's my code:
#include <SDL/SDL.h>
#include <iostream>
#include <string>
#include <vector>
#include <SDL_image/SDL_image.h>
using namespace std;
const Uint32 FRAMES_PER_SECOND = 60;
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int WIDTH = 21;
const int HEIGHT = 25;
SDL_Event sdlEvent;
char getAsciiKey(const SDL_Event &sdlEvent);
int main( int argc, char* args[] )
{
//The surfaces
SDL_Surface* image[2] = {NULL};
SDL_Surface* screen = NULL;
//Start SDL
SDL_Init( SDL_INIT_EVERYTHING );
//Set up screen
screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, 32, SDL_SWSURFACE | SDL_DOUBLEBUF );
char filename[256]; //create a large enough C-string
for(int index = 0; index < 2; index++)
{
sprintf(filename, "Text-types/Arial%d.bmp", index); //Arial0 and Arial1
//Load the image
image[index] = IMG_Load( filename );
if(image == NULL)
{
cout << "Error loading image: " << filename << endl;
exit(1);
}
}
Uint32 color = SDL_MapRGB(screen->format, 0xff,0xff,0xff); //White
SDL_FillRect(screen, &screen->clip_rect, color); //Backgroundcolor -> White
bool quit = false;
//Main program loop
while(quit == false)
{
//Process any events from the event queue - such as key presses or mouse movements
while(SDL_PollEvent(&sdlEvent))
{
if(sdlEvent.type == SDL_QUIT)
{
quit = true;
}
if (sdlEvent.type == SDL_KEYDOWN) //A key has just pressed
{
int x, y, temp;
SDL_Rect srcRect;
SDL_Rect dstRect;
//char letter = getAsciiKey(sdlEvent); //Getting keypress
temp = (static_cast<int>(getAsciiKey(sdlEvent)) - 12);
x = (temp % 20); //X-axis postion
y = (temp / 20); //Y-axis position
srcRect.x = (x - 1) * WIDTH;
srcRect.y = (y - 1) * HEIGHT;
//PIXELSIZE
srcRect.w = WIDTH;
srcRect.h = HEIGHT;
dstRect.x = 0;
dstRect.y = 0;
dstRect.w = WIDTH;
dstRect.h = HEIGHT;
SDL_BlitSurface(image[1] , &srcRect, screen, &dstRect ); //Putting image up on screen
//Update Screen
SDL_Flip( screen );
//Pause
SDL_Delay( 2000 );
}
}
}
//Free any loaded images
for(int index = 0; index < 2; index++)
{
SDL_FreeSurface( image[index] );
}
//Quit SDL
SDL_Quit();
return 0;
}
char getAsciiKey(const SDL_Event &sdlEvent)
{
char key = 0;
if(sdlEvent.key.keysym.sym >= SDLK_a && sdlEvent.key.keysym.sym <= SDLK_z)
{
if(sdlEvent.key.keysym.mod & KMOD_SHIFT)
{
key = 'A' + char(sdlEvent.key.keysym.sym - SDLK_a);
}
else
{
key = 'a' + char(sdlEvent.key.keysym.sym - SDLK_a);
}
}
else if(sdlEvent.key.keysym.sym >= SDLK_0 && sdlEvent.key.keysym.sym <= SDLK_9)
{
key = '0' + char(sdlEvent.key.keysym.sym - SDLK_0);
}
return key;
}
dstRect.x = 0;
dstRect.y = 0;
This is the position you're blitting to, and I don't see you changing it anywhere. Update it for each new character.
Also, this:
dstRect.w = WIDTH;
dstRect.h = HEIGHT;
is redundant, width and height of destination are ignored when blitting (at least the reference for SDL_BlitSurface says so).