Added rbg_gradient.cpp for SDL gradient graphics

graphics/rgb_gradient.cpp

@@ -0,0 +1,87 @@
+// -*- compile-command: "g++ main.cpp -o app -lmingw32 -lSDL2main -lSDL2" -*- for windows mingw
+#include <cstdlib>
+#include <ostream>
+#include <random>
+#define SDL_MAIN_HANDLED
+#include <SDL2/SDL.h>
+#include <iostream>
+#include <functional>
+#include <cstring>
+#include "font8x8_basic.h"
+
+using namespace std;
+
+const int SCREEN_WIDTH = 640;
+const int SCREEN_HEIGHT = 480;
+
+uint32_t pixbuf[SCREEN_WIDTH * SCREEN_HEIGHT]; // one dimensional array of pixels
+
+void draw_menu() {
+  for (int y = 0; y < SCREEN_HEIGHT; y++)
+    for (int x = 0; x < SCREEN_WIDTH; x++) {
+      uint8_t r = x % 256, g = y % 256, b = 0;
+      pixbuf[y * SCREEN_WIDTH + x] = (0xFF << 24) | (r << 16) | (g << 8) | b;
+    }
+}
+
+int main(){
+  if(SDL_Init(SDL_INIT_VIDEO) != 0){
+    std::cerr << "SDL Init Error: " << SDL_GetError() << std::endl;
+    return 1;
+  }
+
+  SDL_Window* window = SDL_CreateWindow(
+					"SoftRaster",
+					SDL_WINDOWPOS_CENTERED,
+					SDL_WINDOWPOS_CENTERED,
+					640, 480,
+					SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE
+					);
+  if(!window){
+    std::cerr << "SDL Create Window Error: " << SDL_GetError() << std::endl;
+    SDL_Quit();
+  }
+
+  SDL_Renderer* renderer = SDL_CreateRenderer(
+					      window, -1, SDL_RENDERER_ACCELERATED
+					      );
+
+  if(!renderer){
+    std::cerr << "SDL Create Renderer Error: " << SDL_GetError() << std::endl;
+    SDL_DestroyWindow(window);
+    SDL_Quit();
+    return 1;
+  }
+
+  SDL_Texture* texture = SDL_CreateTexture(
+    renderer,
+    SDL_PIXELFORMAT_ARGB8888,
+    SDL_TEXTUREACCESS_STREAMING,
+    SCREEN_WIDTH,
+    SCREEN_HEIGHT
+  );
+
+  bool running = true;
+  SDL_Event event;
+
+  while (running) {
+    while (SDL_PollEvent(&event)) {
+      if (event.type == SDL_QUIT) running = false;
+    }
+
+    draw_menu();
+
+    SDL_UpdateTexture(texture, NULL, pixbuf, SCREEN_WIDTH * sizeof(uint32_t));
+    SDL_RenderClear(renderer);
+    SDL_RenderCopy(renderer, texture, NULL, NULL);
+    SDL_RenderPresent(renderer);
+    SDL_Delay(16);
+  }
+
+  SDL_DestroyTexture(texture);
+  SDL_DestroyRenderer(renderer);
+  SDL_DestroyWindow(window);
+  SDL_Quit();
+
+  return 0;
+}