diff --git a/Spacewar.c b/Spacewar.c index 0f75e73..c9999d6 100644 --- a/Spacewar.c +++ b/Spacewar.c @@ -1,4 +1,4 @@ -// SDL Experiment 08, Barra Ó Catháin. +// SDL Experiment 09, Barra Ó Catháin. // =================================== #include #include @@ -28,6 +28,13 @@ static inline double normalizeXYVector(xyVector * vector) return magnitude; } +static inline void rotateXYVector(xyVector * vector, double degrees) +{ + double xComponent = vector->xComponent, yComponent = vector->yComponent; + vector->xComponent = (cos(degrees * 0.01745329) * xComponent) - (sin(degrees * 0.01745329) * yComponent); + vector->yComponent = (sin(degrees * 0.01745329) * xComponent) + (cos(degrees * 0.01745329) * yComponent); +} + // Add vector B to vector A: static inline void addXYVector(xyVector * vectorA, xyVector * vectorB) { @@ -52,7 +59,7 @@ void DrawCircle(SDL_Renderer * renderer, int32_t centreX, int32_t centreY, int32 { const int32_t diameter = (radius * 2); - int32_t x = (radius - 1); + int32_t x = (radius - 1); int32_t y = 0; int32_t tx = 1; int32_t ty = 1; @@ -89,20 +96,20 @@ void DrawCircle(SDL_Renderer * renderer, int32_t centreX, int32_t centreY, int32 int main(int argc, char ** argv) { SDL_Event event; - bool quit = false; + int width = 0, height = 0; long positionX = 0, positionY = 0; - int width = 0, height = 0, mouseX = 0, mouseY = 0; uint32_t rendererFlags = SDL_RENDERER_ACCELERATED; - double deltaTime = 0, gravityMagnitude = 0, gravityAcceleration = 0; + double deltaTime = 0, gravityMagnitude = 0, gravityAcceleration = 0; uint64_t thisFrameTime = SDL_GetPerformanceCounter(), lastFrameTime = 0; - xyVector positionVector = {100, 100}, velocityVector = {20, 0}, gravityVector = {0, 0}; + bool quit = false, rotatingClockwise = false, rotatingAnticlockwise = false, accelerating = false; + xyVector positionVector = {100, 100}, velocityVector = {0, 0}, gravityVector = {0, 0}, engineVector = {0.1, 0}; // Initialize the SDL library, video, sound, and input: if (SDL_Init(SDL_INIT_EVERYTHING) != 0) { printf("SDL Initialization Error: %s\n", SDL_GetError()); } - + // Create an SDL window and rendering context in that window: SDL_Window * window = SDL_CreateWindow("SDL_TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 640, 0); SDL_Renderer * renderer = SDL_CreateRenderer(window, -1, rendererFlags); @@ -126,6 +133,58 @@ int main(int argc, char ** argv) quit = true; break; } + case SDL_KEYDOWN: + { + switch (event.key.keysym.sym) + { + case SDLK_LEFT: + { + rotatingAnticlockwise = true; + break; + } + case SDLK_RIGHT: + { + rotatingClockwise = true; + break; + } + case SDLK_UP: + { + accelerating = true; + break; + } + default: + { + break; + } + } + break; + } + case SDL_KEYUP: + { + switch (event.key.keysym.sym) + { + case SDLK_LEFT: + { + rotatingAnticlockwise = false; + break; + } + case SDLK_RIGHT: + { + rotatingClockwise = false; + break; + } + case SDLK_UP: + { + accelerating = false; + break; + } + default: + { + break; + } + } + break; + } default: { break; @@ -136,25 +195,16 @@ int main(int argc, char ** argv) // Store the window's current width and height: SDL_GetWindowSize(window, &width, &height); - // Store the mouse pointer's current position in the window: - SDL_GetMouseState(&mouseX, &mouseY); - // Calculate the vector between the star and ship: - xyVectorBetweenPoints(positionVector.xComponent, positionVector.yComponent, mouseX, mouseY, &gravityVector); + xyVectorBetweenPoints(positionVector.xComponent, positionVector.yComponent, width/2, height/2, &gravityVector); // Make it into a unit vector: gravityMagnitude = normalizeXYVector(&gravityVector); // Calculate the gravity between the star and ship: - if(gravityMagnitude > 45) - { - gravityAcceleration = 2 * (2500 / pow(gravityMagnitude, 2)); - } - else - { - gravityAcceleration = 0; - multiplyXYVector(&velocityVector, -0.98); - } + gravityAcceleration = (gravityMagnitude >= 45) ? + 0.5 * (2500 / pow(gravityMagnitude, 2)): + 0; // Scale the vector: multiplyXYVector(&gravityVector, gravityAcceleration); @@ -180,10 +230,23 @@ int main(int argc, char ** argv) positionVector.yComponent = height; velocityVector.yComponent *= 0.6; } - + // Rotate the engine vector if needed: + if(rotatingClockwise) + { + rotateXYVector(&engineVector, 0.1); + } + if(rotatingAnticlockwise) + { + rotateXYVector(&engineVector, -0.1); + } + // Calculate the new current velocity: addXYVectorDeltaScaled(&velocityVector, &gravityVector, deltaTime); - + if(accelerating) + { + addXYVectorDeltaScaled(&velocityVector, &engineVector, deltaTime); + } + // Calculate the new position: addXYVectorDeltaScaled(&positionVector, &velocityVector, deltaTime); @@ -206,22 +269,27 @@ int main(int argc, char ** argv) SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255); // Draw a circle in the center as the star: - DrawCircle(renderer, mouseX, mouseY, 30); + DrawCircle(renderer, width/2, height/2, 30); // Draw a line representing the velocity: SDL_RenderDrawLine(renderer, positionX, positionY, - (long)(positionVector.xComponent + velocityVector.xComponent * 3), - (long)(positionVector.yComponent + velocityVector.yComponent * 3)); + (long)(positionVector.xComponent + velocityVector.xComponent * 15), + (long)(positionVector.yComponent + velocityVector.yComponent * 15)); + + // Set the colour to blue: + SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255); + + // Draw a line showing the direction the engine will accelerate: + SDL_RenderDrawLine(renderer, positionX, positionY, + (long)(positionVector.xComponent + engineVector.xComponent * 300), + (long)(positionVector.yComponent + engineVector.yComponent * 300)); // Present the rendered graphics: SDL_RenderPresent(renderer); - - // Delay enough so that we run at 60 frames: - SDL_Delay(1000 / 144); } return 0; } // =========================================================================================== // Local Variables: -// compile-command: "gcc `sdl2-config --libs --cflags` SDL2-Experiment-08.c -lm" +// compile-command: "gcc `sdl2-config --libs --cflags` SDL2-Experiment-09.c -lm" // End: