Added SDL2 Experiment 6, and fixed a bad yank that got copied
- Added Experiment 6, which is a modified version of experiment 5 using delta-time scaling. - Removed the double SDL initialization, which is a no-op, but for the sake of betterment.
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Barry Kane
parent
79e062be5f
commit
3f471188e3
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@ -64,11 +64,6 @@ int main(int argc, char ** argv)
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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IMG_Init(IMG_INIT_PNG);
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// Create an SDL window and rendering context in that window:
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@ -64,11 +64,6 @@ int main(int argc, char ** argv)
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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IMG_Init(IMG_INIT_PNG);
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// Create an SDL window and rendering context in that window:
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@ -64,11 +64,6 @@ int main(int argc, char ** argv)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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// Create an SDL window and rendering context in that window:
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SDL_Window * window = SDL_CreateWindow("SDL_TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 640, 0);
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@ -64,11 +64,6 @@ int main(int argc, char ** argv)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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// Create an SDL window and rendering context in that window:
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SDL_Window * window = SDL_CreateWindow("SDL_TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 640, 0);
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@ -60,11 +60,6 @@ int main(int argc, char ** argv)
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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// Create an SDL window and rendering context in that window:
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SDL_Window * window = SDL_CreateWindow("SDL_TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 640, 0);
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SDL_Renderer * renderer = SDL_CreateRenderer(window, -1, rendererFlags);
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@ -105,7 +100,7 @@ int main(int argc, char ** argv)
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gravityY /= gravityMagnitude;
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// Calculate the gravity between them and scale the vector:
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if(gravityMagnitude > 15)
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if(gravityMagnitude > 15)
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{
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gravityAcceleration = 2 * (2500 / pow(gravityMagnitude, 2));
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gravityX *= gravityAcceleration;
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@ -0,0 +1,183 @@
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// SDL Experiment 06, Barra Ó Catháin.
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// ===================================
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#include <SDL2/SDL.h>
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#include <SDL2/SDL_timer.h>
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#include <math.h>
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#include <stdbool.h>
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#include <stdint.h>
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void DrawCircle(SDL_Renderer * renderer, int32_t centreX, int32_t centreY, int32_t radius)
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{
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const int32_t diameter = (radius * 2);
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int32_t x = (radius - 1);
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int32_t y = 0;
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int32_t tx = 1;
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int32_t ty = 1;
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int32_t error = (tx - diameter);
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while (x >= y)
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{
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// Each of the following renders an octant of the circle
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SDL_RenderDrawPoint(renderer, centreX + x, centreY - y);
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SDL_RenderDrawPoint(renderer, centreX + x, centreY + y);
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SDL_RenderDrawPoint(renderer, centreX - x, centreY - y);
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SDL_RenderDrawPoint(renderer, centreX - x, centreY + y);
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SDL_RenderDrawPoint(renderer, centreX + y, centreY - x);
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SDL_RenderDrawPoint(renderer, centreX + y, centreY + x);
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SDL_RenderDrawPoint(renderer, centreX - y, centreY - x);
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SDL_RenderDrawPoint(renderer, centreX - y, centreY + x);
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if (error <= 0)
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{
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++y;
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error += ty;
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ty += 2;
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}
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if (error > 0)
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{
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--x;
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tx += 2;
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error += (tx - diameter);
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}
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}
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}
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int main(int argc, char ** argv)
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{
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SDL_Event event;
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bool quit = false;
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int width = 0, height = 0;
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uint64_t thisFrameTime = SDL_GetPerformanceCounter(), lastFrameTime = 0;
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uint32_t rendererFlags = SDL_RENDERER_ACCELERATED;
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double posX = 0, posY = 0, deltaTime = 0;
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long positionX = 0, positionY = 0;
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double velocityX = 20, velocityY = 0, gravityX = 0, gravityY = 0, gravityMagnitude = 0, gravityAcceleration = 0;
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// Initialize the SDL library, video, sound, and input:
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if (SDL_Init(SDL_INIT_EVERYTHING) != 0)
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{
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printf("SDL Initialization Error: %s\n", SDL_GetError());
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}
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// Create an SDL window and rendering context in that window:
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SDL_Window * window = SDL_CreateWindow("SDL_TEST", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 640, 0);
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SDL_Renderer * renderer = SDL_CreateRenderer(window, -1, rendererFlags);
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// Enable resizing the window:
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SDL_SetWindowResizable(window, SDL_TRUE);
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while (!quit)
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{
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lastFrameTime = thisFrameTime;
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thisFrameTime = SDL_GetPerformanceCounter();
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deltaTime = (double)(((thisFrameTime - lastFrameTime) * 1000) / (double)SDL_GetPerformanceFrequency());
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// Check if the user wants to quit:
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while (SDL_PollEvent(&event))
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{
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switch (event.type)
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{
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case SDL_QUIT:
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{
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quit = true;
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break;
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}
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default:
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{
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break;
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}
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}
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}
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// Store the window's current width and height:
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SDL_GetWindowSize(window, &width, &height);
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// Calculate the gravity vector:
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// Calculate the vector between the star and ship:
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gravityX = (width/2 - posX);
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gravityY = (height/2 - posY);
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// Make it into a unit vector:
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gravityMagnitude = sqrt(pow(gravityX, 2) + pow(gravityY, 2));
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gravityX /= gravityMagnitude;
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gravityY /= gravityMagnitude;
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// Calculate the gravity between them and scale the vector:
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if(gravityMagnitude > 15)
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{
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gravityAcceleration = 2 * (2500 / pow(gravityMagnitude, 2));
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gravityX *= gravityAcceleration;
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gravityY *= gravityAcceleration;
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}
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else
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{
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gravityAcceleration = 0.02 * (2500 / pow(gravityMagnitude, 2));
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gravityX *= gravityAcceleration;
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gravityY *= gravityAcceleration;
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}
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// Wrap the position if the ship goes off-screen:
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if(posX > width + 15)
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{
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posX = 0;
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velocityX *= 0.6;
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}
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if(posY > height + 15)
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{
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posY = 0;
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velocityY *= 0.6;
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}
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if(posX < -15)
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{
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posX = width;
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velocityX *= 0.6;
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}
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if(posY < -15)
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{
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posY = height;
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velocityY *= 0.6;
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}
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// Calculate the new current velocity:
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velocityX += gravityX * (deltaTime * 0.001) * 60;
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velocityY += gravityY * (deltaTime * 0.001) * 60;
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// Calculate the new position:
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posX += velocityX * (deltaTime * 0.001) * 60;
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posY += velocityY * (deltaTime * 0.001) * 60;
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positionX = (long)posX;
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positionY = (long)posY;
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// Set the colour to black:
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SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
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// Clear the screen, filling it with black:
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SDL_RenderClear(renderer);
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// Set the colour to green:
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SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
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// Draw a circle "ship" around the current position:
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DrawCircle(renderer, positionX, positionY, 15);
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// Set the colour to yellow:
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SDL_SetRenderDrawColor(renderer, 255, 255, 0, 255);
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// Draw a circle in the center as the star:
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DrawCircle(renderer, width/2, height/2, 30);
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// Draw a line representing the velocity:
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SDL_RenderDrawLine(renderer, positionX, positionY, (long)(posX + velocityX * 3), (long)(posY + velocityY * 3));
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// Present the rendered graphics:
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SDL_RenderPresent(renderer);
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}
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return 0;
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}
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// ===========================================================================================
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// Local Variables:
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// compile-command: "gcc `sdl2-config --libs --cflags` SDL2-Experiment-06.c -lm"
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// End:
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