A simple gravity simulation inspired by "Spacewar!". I'm going to make this into a Spacewar! clone.
This commit is contained in:
parent
6f966fec57
commit
6df411a1a2
|
|
@ -1,7 +1,8 @@
|
|||
// SDL Experiment 04, Barra Ó Catháin.
|
||||
// SDL Experiment 05, Barra Ó Catháin.
|
||||
// ===================================
|
||||
#include <SDL2/SDL.h>
|
||||
#include <SDL2/SDL_timer.h>
|
||||
#include <math.h>
|
||||
#include <stdbool.h>
|
||||
#include <stdint.h>
|
||||
|
||||
|
|
@ -43,21 +44,15 @@ void DrawCircle(SDL_Renderer * renderer, int32_t centreX, int32_t centreY, int32
|
|||
}
|
||||
}
|
||||
|
||||
// Get the largest radius for a circle that can fit in the width and height of a rectangle:
|
||||
static inline int getRadius(int width, int height)
|
||||
{
|
||||
return (width/2 < height/2) ? width/2 : height/2;
|
||||
}
|
||||
|
||||
|
||||
int main(int argc, char ** argv)
|
||||
{
|
||||
SDL_Event event;
|
||||
bool quit = false;
|
||||
int width = 0, height = 0;
|
||||
uint32_t rendererFlags = SDL_RENDERER_ACCELERATED;
|
||||
long positionX = 320, positionY = 320, velocityX = 0, velocityY = 0;
|
||||
bool accelLeft = false, accelRight = false, accelUp = false, accelDown = false;
|
||||
double posX = 0, posY = 0;
|
||||
long positionX = 0, positionY = 0;
|
||||
double velocityX = 20, velocityY = 0, gravityX = 0, gravityY = 0, gravityMagnitude = 0, gravityAcceleration = 0;
|
||||
|
||||
// Initialize the SDL library, video, sound, and input:
|
||||
if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
|
||||
|
|
@ -84,177 +79,103 @@ int main(int argc, char ** argv)
|
|||
quit = true;
|
||||
break;
|
||||
}
|
||||
// Begin accelerating in the direction that is pressed:
|
||||
case SDL_KEYDOWN:
|
||||
{
|
||||
switch (event.key.keysym.sym)
|
||||
{
|
||||
case SDLK_LEFT:
|
||||
{
|
||||
accelLeft = true;
|
||||
break;
|
||||
}
|
||||
case SDLK_RIGHT:
|
||||
{
|
||||
accelRight = true;
|
||||
break;
|
||||
}
|
||||
case SDLK_UP:
|
||||
{
|
||||
accelUp = true;
|
||||
break;
|
||||
}
|
||||
case SDLK_DOWN:
|
||||
{
|
||||
accelDown = true;
|
||||
break;
|
||||
}
|
||||
default:
|
||||
{
|
||||
break;
|
||||
}
|
||||
}
|
||||
break;
|
||||
}
|
||||
// Stop accelerating in the direction that is released:
|
||||
case SDL_KEYUP:
|
||||
{
|
||||
switch (event.key.keysym.sym)
|
||||
{
|
||||
case SDLK_LEFT:
|
||||
{
|
||||
accelLeft = false;
|
||||
break;
|
||||
}
|
||||
case SDLK_RIGHT:
|
||||
{
|
||||
accelRight = false;
|
||||
break;
|
||||
}
|
||||
case SDLK_UP:
|
||||
{
|
||||
accelUp = false;
|
||||
break;
|
||||
}
|
||||
case SDLK_DOWN:
|
||||
{
|
||||
accelDown = false;
|
||||
break;
|
||||
}
|
||||
default:
|
||||
{
|
||||
break;
|
||||
}
|
||||
}
|
||||
break;
|
||||
}
|
||||
default:
|
||||
{
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Accelerate:
|
||||
if(accelLeft)
|
||||
{
|
||||
velocityX -= 2;
|
||||
}
|
||||
|
||||
if(accelRight)
|
||||
{
|
||||
velocityX += 2;
|
||||
}
|
||||
|
||||
if(accelUp)
|
||||
{
|
||||
velocityY -= 2;
|
||||
}
|
||||
|
||||
if(accelDown)
|
||||
{
|
||||
velocityY += 2;
|
||||
}
|
||||
|
||||
// Limit velocity:
|
||||
if(velocityX > 10)
|
||||
{
|
||||
velocityX = 10;
|
||||
}
|
||||
|
||||
if(velocityX < -10)
|
||||
{
|
||||
velocityX = -10;
|
||||
}
|
||||
|
||||
|
||||
// Deccelerate:
|
||||
if(velocityX != 0)
|
||||
{
|
||||
velocityX = (velocityX < 0) ? velocityX + 1 : velocityX - 1;
|
||||
}
|
||||
|
||||
if(positionY < 640)
|
||||
{
|
||||
velocityY += 1;
|
||||
}
|
||||
if(positionY >= 640 && velocityY !=0 && !accelUp)
|
||||
{
|
||||
velocityY *= -1;
|
||||
velocityY += 1;
|
||||
}
|
||||
|
||||
|
||||
// Move the position:
|
||||
if(velocityX != 0)
|
||||
{
|
||||
positionX += velocityX;
|
||||
if(positionX < 0)
|
||||
{
|
||||
positionX = 640;
|
||||
}
|
||||
if(positionX > 640)
|
||||
{
|
||||
positionX = 0;
|
||||
}
|
||||
}
|
||||
if(velocityY != 0)
|
||||
{
|
||||
positionY += velocityY;
|
||||
if(positionY < 0)
|
||||
{
|
||||
positionY = 0;
|
||||
}
|
||||
if(positionY > 640)
|
||||
{
|
||||
positionY = 640;
|
||||
}
|
||||
}
|
||||
|
||||
// Store the window's current width and height:
|
||||
SDL_GetWindowSize(window, &width, &height);
|
||||
|
||||
// Calculate the gravity vector:
|
||||
// Calculate the vector between the star and ship:
|
||||
gravityX = (width/2 - posX);
|
||||
gravityY = (height/2 - posY);
|
||||
|
||||
// Make it into a unit vector:
|
||||
gravityMagnitude = sqrt(pow(gravityX, 2) + pow(gravityY, 2));
|
||||
gravityX /= gravityMagnitude;
|
||||
gravityY /= gravityMagnitude;
|
||||
|
||||
// Calculate the gravity between them and scale the vector:
|
||||
if(gravityMagnitude > 15)
|
||||
{
|
||||
gravityAcceleration = 2 * (2500 / pow(gravityMagnitude, 2));
|
||||
gravityX *= gravityAcceleration;
|
||||
gravityY *= gravityAcceleration;
|
||||
}
|
||||
else
|
||||
{
|
||||
gravityAcceleration = 0.02 * (2500 / pow(gravityMagnitude, 2));
|
||||
gravityX *= gravityAcceleration;
|
||||
gravityY *= gravityAcceleration;
|
||||
}
|
||||
|
||||
// Wrap the position if the ship goes off-screen:
|
||||
if(posX > width + 15)
|
||||
{
|
||||
posX = 0;
|
||||
velocityX *= 0.6;
|
||||
}
|
||||
if(posY > height + 15)
|
||||
{
|
||||
posY = 0;
|
||||
velocityY *= 0.6;
|
||||
}
|
||||
if(posX < -15)
|
||||
{
|
||||
posX = width;
|
||||
velocityX *= 0.6;
|
||||
}
|
||||
if(posY < -15)
|
||||
{
|
||||
posY = height;
|
||||
velocityY *= 0.6;
|
||||
}
|
||||
|
||||
// Calculate the new current velocity:
|
||||
velocityX += gravityX;
|
||||
velocityY += gravityY;
|
||||
|
||||
// Calculate the new position:
|
||||
posX += velocityX;
|
||||
posY += velocityY;
|
||||
|
||||
positionX = (long)posX;
|
||||
positionY = (long)posY;
|
||||
|
||||
// Set the colour to black:
|
||||
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
|
||||
|
||||
// Clear the screen, filling it with black:
|
||||
SDL_RenderClear(renderer);
|
||||
|
||||
// Set the colour to green:
|
||||
SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
|
||||
|
||||
// Draw a circle "ship" around the current position:
|
||||
DrawCircle(renderer, positionX, positionY, 15);
|
||||
|
||||
// Set the colour to yellow:
|
||||
SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255);
|
||||
|
||||
// Draw a circle around the position pointer:
|
||||
DrawCircle(renderer, positionX, positionY, 15);
|
||||
// Draw a circle in the center as the star:
|
||||
DrawCircle(renderer, width/2, height/2, 30);
|
||||
|
||||
// Draw a line representing the velocity:
|
||||
SDL_RenderDrawLine(renderer, positionX, positionY, (long)((posX + velocityX * 3)), (long)((posY + velocityY * 3)));
|
||||
|
||||
// Present the rendered graphics:
|
||||
SDL_RenderPresent(renderer);
|
||||
|
||||
// Delay enough so that we run at 144 frames:
|
||||
// Delay enough so that we run at 60 frames:
|
||||
SDL_Delay(1000 / 60);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
// ===========================================================================================
|
||||
// Local Variables:
|
||||
// compile-command: "gcc `sdl2-config --libs --cflags` SDL2-Experiment-04.c -lm"
|
||||
// compile-command: "gcc `sdl2-config --libs --cflags` SDL2-Experiment-05.c -lm"
|
||||
// End:
|
||||
Loading…
Reference in New Issue