当我尝试编译以下课程时 http://lazyfoo.net/downloads/index.php?file=SDLTut_lesson19
我在Visual Studio 2010中有这个输出：
1>------ Build started: Project: 19-circularcollisiondetect, Configuration: Debug Win32 ------
1>Build started 02/03/2012 03:47:51.
1>InitializeBuildStatus:
1> Touching "Debug\19-circularcollisiondetect.unsuccessfulbuild".
1>ClCompile:
1> main.cpp
1>c:\users\fab\desktop\c++\sdl 1.2.15\19-circularcollisiondetect\19-circularcollisiondetect\main.cpp(140): error C2668: 'pow' : ambiguous call to overloaded function
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(583): could be 'long double pow(long double,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(535): or 'float pow(float,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(497): or 'double pow(double,int)'
1> while trying to match the argument list '(int, int)'
1>c:\users\fab\desktop\c++\sdl 1.2.15\19-circularcollisiondetect\19-circularcollisiondetect\main.cpp(140): error C2668: 'pow' : ambiguous call to overloaded function
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(583): could be 'long double pow(long double,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(535): or 'float pow(float,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(497): or 'double pow(double,int)'
1> while trying to match the argument list '(int, int)'
1>c:\users\fab\desktop\c++\sdl 1.2.15\19-circularcollisiondetect\19-circularcollisiondetect\main.cpp(162): warning C4018: '<' : signed/unsigned mismatch
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.80
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
我该如何解决？ 我正在使用Visual Studio 2010和SDL 1.2.15。我没有修改原始代码。 你能验证一下是否可以编译它？
/*This source code copyrighted by Lazy Foo' Productions (2004-2012)
and may not be redestributed without written permission.*/
//The headers
#include "SDL.h"
#include "SDL_image.h"
#include <string>
#include <vector>
#include <cmath>
//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 dot attributes
const int DOT_WIDTH = 20;
//The surfaces
SDL_Surface *dot = NULL;
SDL_Surface *screen = NULL;
//The event structure
SDL_Event event;
//A circle structure
struct Circle
{
int x, y;
int r;
};
//The dot
class Dot
{
private:
//The area of the dot
Circle c;
//The velocity of the dot
int xVel, yVel;
public:
//Initializes the variables
Dot();
//Takes key presses and adjusts the dot's velocity
void handle_input();
//Moves the dot
void move( std::vector<SDL_Rect> &rects, Circle &circle );
//Shows the dot on the screen
void show();
};
//The timer class
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 );
}
double distance( int x1, int y1, int x2, int y2 )
{
//Return the distance between the two points
return sqrt( pow( x2 - x1, 2 ) + pow( y2 - y1, 2 ) );
}
bool check_collision( Circle &A, Circle &B )
{
//If the distance between the centers of the circles is less than the sum of their radii
if( distance( A.x, A.y, B.x, B.y ) < ( A.r + B.r ) )
{
//The circles have collided
return true;
}
//If not
return false;
}
bool check_collision( Circle &A, std::vector<SDL_Rect> &B )
{
//Closest point on collision box
int cX, cY;
//Go through the B boxes
for( int Bbox = 0; Bbox < B.size(); Bbox++ )
{
//Find closest x offset
if( A.x < B[ Bbox ].x )
{
cX = B[ Bbox ].x;
}
else if( A.x > B[ Bbox ].x + B[ Bbox ].w )
{
cX = B[ Bbox ].x + B[ Bbox ].w;
}
else
{
cX = A.x;
}
//Find closest y offset
if( A.y < B[ Bbox ].y )
{
cY = B[ Bbox ].y;
}
else if( A.y > B[ Bbox ].y + B[ Bbox ].h )
{
cY = B[ Bbox ].y + B[ Bbox ].h;
}
else
{
cY = A.y;
}
//If the closest point is inside the circle
if( distance( A.x, A.y, cX, cY ) < A.r )
{
//This box and the circle have collided
return true;
}
}
//If the shapes have not collided
return false;
}
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 Dot", NULL );
//If everything initialized fine
return true;
}
bool load_files()
{
//Load the dot image
dot = load_image( "dot.bmp" );
//If there was a problem in loading the dot
if( dot == NULL )
{
return false;
}
//If everything loaded fine
return true;
}
void clean_up()
{
//Free the surface
SDL_FreeSurface( dot );
//Quit SDL
SDL_Quit();
}
Dot::Dot()
{
//Initialize the offsets and dimentions
c.x = DOT_WIDTH / 2;
c.y = DOT_WIDTH / 2;
c.r = DOT_WIDTH / 2;
//Initialize the velocity
xVel = 0;
yVel = 0;
}
void Dot::handle_input()
{
//If a key was pressed
if( event.type == SDL_KEYDOWN )
{
//Adjust the velocity
switch( event.key.keysym.sym )
{
case SDLK_UP: yVel -= 1; break;
case SDLK_DOWN: yVel += 1; break;
case SDLK_LEFT: xVel -= 1; break;
case SDLK_RIGHT: xVel += 1; break;
}
}
//If a key was released
else if( event.type == SDL_KEYUP )
{
//Adjust the velocity
switch( event.key.keysym.sym )
{
case SDLK_UP: yVel += 1; break;
case SDLK_DOWN: yVel -= 1; break;
case SDLK_LEFT: xVel += 1; break;
case SDLK_RIGHT: xVel -= 1; break;
}
}
}
void Dot::move( std::vector<SDL_Rect> &rects, Circle &circle )
{
//Move the dot left or right
c.x += xVel;
//If the dot went too far to the left or right or has collided with the other shapes
if( ( c.x - DOT_WIDTH / 2 < 0 ) || ( c.x + DOT_WIDTH / 2 > SCREEN_WIDTH ) || ( check_collision( c, rects ) ) || ( check_collision( c, circle ) ) )
{
//Move back
c.x -= xVel;
}
//Move the dot up or down
c.y += yVel;
//If the dot went too far up or down or has collided with the other shapes
if( ( c.y - DOT_WIDTH / 2 < 0 ) || ( c.y + DOT_WIDTH / 2 > SCREEN_HEIGHT ) || ( check_collision( c, rects ) ) || ( check_collision( c, circle ) ) )
{
//Move back
c.y -= yVel;
}
}
void Dot::show()
{
//Show the dot
apply_surface( c.x - c.r, c.y - c.r, dot, 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;
//Make the dot
Dot myDot;
//Make the shapes
std::vector<SDL_Rect> box( 1 );
Circle otherDot;
//Set the shapes' attributes
box[ 0 ].x = 60;
box[ 0 ].y = 60;
box[ 0 ].w = 40;
box[ 0 ].h = 40;
otherDot.x = 30;
otherDot.y = 30;
otherDot.r = DOT_WIDTH / 2;
//The frame rate regulator
Timer fps;
//Initialize
if( init() == false )
{
return 1;
}
//Load the files
if( load_files() == false )
{
return 1;
}
//While the user hasn't quit
while( quit == false )
{
//Start the frame timer
fps.start();
//While there's events to handle
while( SDL_PollEvent( &event ) )
{
//Handle events for the dot
myDot.handle_input();
//If the user has Xed out the window
if( event.type == SDL_QUIT )
{
//Quit the program
quit = true;
}
}
//Move the dot
myDot.move( box, otherDot );
//Fill the screen white
SDL_FillRect( screen, &screen->clip_rect, SDL_MapRGB( screen->format, 0xFF, 0xFF, 0xFF ) );
//Show the box
SDL_FillRect( screen, &box[ 0 ], SDL_MapRGB( screen->format, 0x00, 0x00, 0x00 ) );
//Show the other dot
apply_surface( otherDot.x - otherDot.r, otherDot.y - otherDot.r, dot, screen );
//Show our dot
myDot.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;
}
答案 0 :(得分：1)
如错误所示：
1>c:\users\fab\desktop\c++\sdl 1.2.15\19-circularcollisiondetect\19-circularcollisiondetect\main.cpp(140): error C2668: 'pow' : ambiguous call to overloaded function
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(583): could be 'long double pow(long double,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(535): or 'float pow(float,int)'
1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\math.h(497): or 'double pow(double,int)'
你将两个整数传递给pow（），但它需要一个long double和int，float和int，或者double和int。铸造其中一个应该为你解决这个问题，例如：
return sqrt( pow((double)(x2 - x1), 2 ) + pow((double)(y2 - y1), 2 ) );
我在这里使用了double，因为它可以更准确地表示整个范围的整数，而不是浮动而不会过度杀戮，但是如果你处理的是小数字（在100和1000中）你可能只需使用浮动。
答案 1 :(得分：0)
错误基本上是说数学函数pow有多个定义，编译器不知道在这种情况下自动选择哪一个。尝试在行中显式地转换整数（x1，x2，y1，y2）：
return sqrt( pow( x2 - x1, 2 ) + pow( y2 - y1, 2 ) );
...像这样浮动：
return sqrt( pow( (float)( x2 - x1 ), 2 ) + pow( (float)( y2 - y1 ), 2 ) );