如何使用SDL一次处理多个按键? 使用C++对ubuntu上的SDL编程,使自己熟悉OpenGL编程。经过一些环顾四周和试验,我开始明白了。我需要关于SDL键盘事件处理的建议
我有一个第一人称相机,可以向前走,向后走,左右扫射,用鼠标环顾四周,这很好。以下是我的processEvents函数:如何使用SDL一次处理多个按键? 使用C++对ubuntu上的SDL编程,使自己熟悉OpenGL编程。经过一些环顾四周和试验,我开始明白了。我需要关于SDL键盘事件处理的建议,c++,linux,opengl,ubuntu,sdl,C++,Linux,Opengl,Ubuntu,Sdl,我有一个第一人称相机,可以向前走,向后走,左右扫射,用鼠标环顾四周,这很好。以下是我的processEvents函数: void processEvents() { int mid_x = screen_width >> 1; int mid_y = screen_height >> 1; int mpx = event.motion.x; int mpy = event.motion.y; float angle_y = 0.0f; float angle_
void processEvents()
{
int mid_x = screen_width >> 1;
int mid_y = screen_height >> 1;
int mpx = event.motion.x;
int mpy = event.motion.y;
float angle_y = 0.0f;
float angle_z = 0.0f;
while(SDL_PollEvent(&event))
{
switch(event.type)
{
case SDL_KEYDOWN:
switch(event.key.keysym.sym)
{
case SDLK_ESCAPE:
quit = true;
break;
case SDLK_w:
objCamera.Move_Camera( CAMERASPEED);
break;
case SDLK_s:
objCamera.Move_Camera(-CAMERASPEED);
break;
case SDLK_d:
objCamera.Strafe_Camera( CAMERASPEED);
break;
case SDLK_a:
objCamera.Strafe_Camera(-CAMERASPEED);
break;
default:
break;
}
break;
case SDL_MOUSEMOTION:
if( (mpx == mid_x) && (mpy == mid_y) ) return;
SDL_WarpMouse(mid_x, mid_y);
// Get the direction from the mouse cursor, set a resonable maneuvering speed
angle_y = (float)( (mid_x - mpx) ) / 1000;
angle_z = (float)( (mid_y - mpy) ) / 1000;
// The higher the value is the faster the camera looks around.
objCamera.mView.y += angle_z * 2;
// limit the rotation around the x-axis
if((objCamera.mView.y - objCamera.mPos.y) > 8) objCamera.mView.y = objCamera.mPos.y + 8;
if((objCamera.mView.y - objCamera.mPos.y) <-8) objCamera.mView.y = objCamera.mPos.y - 8;
objCamera.Rotate_View(-angle_y);
break;
case SDL_QUIT:
quit = true;
break;
case SDL_VIDEORESIZE:
screen = SDL_SetVideoMode( event.resize.w, event.resize.h, screen_bpp, SDL_OPENGL | SDL_HWSURFACE | SDL_RESIZABLE | SDL_GL_DOUBLEBUFFER | SDL_HWPALETTE );
screen_width = event.resize.w;
screen_height = event.resize.h;
init_opengl();
std::cout << "Resized to width: " << event.resize.w << " height: " << event.resize.h << std::endl;
break;
default:
break;
}
}
}
void processEvents()
{
int mid_x=屏幕宽度>>1;
int mid_y=屏幕高度>>1;
int mpx=event.motion.x;
int-mpy=event.motion.y;
浮动角度_y=0.0f;
浮动角度_z=0.0f;
while(SDL_事件和事件))
{
开关(事件类型)
{
案例SDL_按键关闭:
开关(event.key.keysym.sym)
{
案例SDLK_逃生:
退出=真;
打破
案例SDLK\U w:
移动摄像机(摄像机速度);
打破
案例SDLK_s:
移动相机(-CAMERASPEED);
打破
案例SDLK\U d:
目标照相机。扫射照相机(照相机速度);
打破
案例SDLK_a:
扫射照相机(-CAMERASPEED);
打破
违约:
打破
}
打破
案例SDL_:
if((mpx==mid_x)和&(mpy==mid_y))返回;
SDL_鼠标(中x、中y);
//从鼠标光标获取方向,设置合理的操纵速度
角度y=(浮动)((中间x-mpx))/1000;
角度z=(浮动)((中间y-mpy))/1000;
//该值越高,摄影机环视四周的速度越快。
objCamera.mView.y+=角度_z*2;
//限制绕x轴旋转
如果((objCamera.mView.y-objCamera.mPos.y)>8)objCamera.mView.y=objCamera.mPos.y+8;
如果((objCamera.mView.y-objCamera.mPos.y)不只是查看keydown事件,任何一次关注多个关键点的解决方案都必须同时查看keydown和keydup事件,并跟踪相关关键点的状态
因此,代替(伪代码):
相反,您会有更像(同样是伪代码)的东西:
然后,updateMovement
例程将查看keystates
,并根据所有移动键的状态计算出一个组合移动。SDL跟踪所有键的当前状态。您可以通过以下方式访问此状态:
因此,每次迭代都可以根据按键状态更新移动。要使移动平稳,应根据更新之间经过的时间更新移动幅度。一个好方法是编写一个键盘(“输入”)处理程序,该处理程序将处理输入事件,并将事件的状态保持在某种结构中(关联数组听起来不错-键[keyCode])
每次键盘处理程序接收到“按键按下”事件时,它都会将按键设置为已启用(true),而当它接收到按键按下事件时,它会将其设置为已禁用(false)
然后,您可以一次检查多个键,而无需直接拉取事件,并且您将能够在整个帧上重复使用键盘,而无需将其传递给子例程
一些快速伪代码:
class KeyboardHandler {
handleKeyboardEvent(SDL Event) {
keyState[event.code] = event.state;
}
bool isPressed(keyCode) {
return (keyState[keyCode] == PRESSED);
}
bool isReleased(keyCode) {
return (keyState[keyCode] == RELEASED);
}
keyState[];
}
...
while(SDL Pull events)
{
switch(event.type) {
case SDL_KEYDOWN:
case SDL_KEYUP:
keyHandler.handleKeyboardEvent(event);
break;
case SDL_ANOTHER_EVENT:
...
break;
}
}
// When you need to use it:
if(keyHandler.isPressed(SOME_KEY) && keyHandler.isPressed(SOME_OTHER_KEY))
doStuff(TM);
使用获取键盘状态如果使用SDL2,则使用
例如:
const Uint8 *keyboard_state_array = SDL_GetKeyboardState(NULL);
SDL_PollEvent(&event);
if(event.type == SDL_KEYDOWN || event.type == SDL_KEYUP)
{
// Move centerpoint of rotation for one of the trees:
if (keyboard_state_array[SDL_SCANCODE_UP] && !(keyboard_state_array[SDL_SCANCODE_DOWN]))
{
--location.y;
}
else if (!keyboard_state_array[SDL_SCANCODE_UP] && keyboard_state_array[SDL_SCANCODE_DOWN])
{
++location.y;
}
if (keyboard_state_array[SDL_SCANCODE_RIGHT] && !keyboard_state_array[SDL_SCANCODE_LEFT])
{
++location.x;
}
else if (!keyboard_state_array[SDL_SCANCODE_RIGHT] && keyboard_state_array[SDL_SCANCODE_LEFT])
{
--location.x;
}
}
这真是一个很好的解决方案,几乎可以在你的所有游戏中使用。除了其他ifs
和&&s
,我们可以只放ifs,一切都一样,不需要附加条件。
class KeyboardHandler {
handleKeyboardEvent(SDL Event) {
keyState[event.code] = event.state;
}
bool isPressed(keyCode) {
return (keyState[keyCode] == PRESSED);
}
bool isReleased(keyCode) {
return (keyState[keyCode] == RELEASED);
}
keyState[];
}
...
while(SDL Pull events)
{
switch(event.type) {
case SDL_KEYDOWN:
case SDL_KEYUP:
keyHandler.handleKeyboardEvent(event);
break;
case SDL_ANOTHER_EVENT:
...
break;
}
}
// When you need to use it:
if(keyHandler.isPressed(SOME_KEY) && keyHandler.isPressed(SOME_OTHER_KEY))
doStuff(TM);
const Uint8 *keyboard_state_array = SDL_GetKeyboardState(NULL);
SDL_PollEvent(&event);
if(event.type == SDL_KEYDOWN || event.type == SDL_KEYUP)
{
// Move centerpoint of rotation for one of the trees:
if (keyboard_state_array[SDL_SCANCODE_UP] && !(keyboard_state_array[SDL_SCANCODE_DOWN]))
{
--location.y;
}
else if (!keyboard_state_array[SDL_SCANCODE_UP] && keyboard_state_array[SDL_SCANCODE_DOWN])
{
++location.y;
}
if (keyboard_state_array[SDL_SCANCODE_RIGHT] && !keyboard_state_array[SDL_SCANCODE_LEFT])
{
++location.x;
}
else if (!keyboard_state_array[SDL_SCANCODE_RIGHT] && keyboard_state_array[SDL_SCANCODE_LEFT])
{
--location.x;
}
}