init

utils/gfx/gfx.c

+/// @file gfx.c
+/// @author Florent Gluck
+/// @date November 6, 2016
+/// Helper routines to render pixels in fullscreen graphic mode.
+/// Uses the SDL2 library.
+
+#include "gfx.h"
+#include <assert.h>
+
+/// Create a fullscreen graphic window.
+/// @param title Title of the window.
+/// @param width Width of the window in pixels.
+/// @param height Height of the window in pixels.
+/// @return a pointer to the graphic context or NULL if it failed.
+struct gfx_context_t *gfx_create(char *title, uint32_t width, uint32_t height)
+{
+    if (SDL_Init(SDL_INIT_VIDEO) != 0)
+        goto error;
+    SDL_Window *window = SDL_CreateWindow(title, SDL_WINDOWPOS_UNDEFINED,
+                                          SDL_WINDOWPOS_UNDEFINED, width, height, SDL_WINDOW_RESIZABLE);
+    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, 0);
+    SDL_Texture *texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888,
+                                             SDL_TEXTUREACCESS_STREAMING, width, height);
+    uint32_t *pixels = malloc(width * height * sizeof(uint32_t));
+    struct gfx_context_t *ctxt = malloc(sizeof(struct gfx_context_t));
+
+    if (!window || !renderer || !texture || !pixels || !ctxt)
+        goto error;
+
+    ctxt->renderer = renderer;
+    ctxt->texture = texture;
+    ctxt->window = window;
+    ctxt->width = width;
+    ctxt->height = height;
+    ctxt->pixels = pixels;
+
+    SDL_ShowCursor(SDL_DISABLE);
+    gfx_clear(ctxt, COLOR_BLACK);
+    return ctxt;
+
+error:
+    return NULL;
+}
+
+/// Draw a pixel in the specified graphic context.
+/// @param ctxt Graphic context where the pixel is to be drawn.
+/// @param column X coordinate of the pixel.
+/// @param row Y coordinate of the pixel.
+/// @param color Color of the pixel.
+void gfx_putpixel(struct gfx_context_t *ctxt, uint32_t column, uint32_t row, uint32_t color)
+{
+    if (column < ctxt->width && row < ctxt->height)
+        ctxt->pixels[ctxt->width * row + column] = color;
+}
+
+/// Clear the specified graphic context.
+/// @param ctxt Graphic context to clear.
+/// @param color Color to use.
+void gfx_clear(struct gfx_context_t *ctxt, uint32_t color)
+{
+    int n = ctxt->width * ctxt->height;
+    while (n)
+        ctxt->pixels[--n] = color;
+}
+
+/// Display the graphic context.
+/// @param ctxt Graphic context to clear.
+void gfx_present(struct gfx_context_t *ctxt)
+{
+    SDL_UpdateTexture(
+        ctxt->texture, NULL, ctxt->pixels, ctxt->width * sizeof(uint32_t));
+    SDL_RenderCopy(ctxt->renderer, ctxt->texture, NULL, NULL);
+    SDL_RenderPresent(ctxt->renderer);
+}
+
+/// Destroy a graphic window.
+/// @param ctxt Graphic context of the window to close.
+void gfx_destroy(struct gfx_context_t *ctxt)
+{
+    SDL_ShowCursor(SDL_ENABLE);
+    SDL_DestroyTexture(ctxt->texture);
+    SDL_DestroyRenderer(ctxt->renderer);
+    SDL_DestroyWindow(ctxt->window);
+    free(ctxt->pixels);
+    ctxt->texture = NULL;
+    ctxt->renderer = NULL;
+    ctxt->window = NULL;
+    ctxt->pixels = NULL;
+    SDL_Quit();
+    free(ctxt);
+}
+
+/// If a key was pressed, returns its key code (non blocking call).
+/// List of key codes: https://wiki.libsdl.org/SDL_Keycode
+/// @return the key that was pressed or 0 if none was pressed.
+SDL_Keycode gfx_keypressed()
+{
+    SDL_Event event;
+    if (SDL_PollEvent(&event))
+    {
+        if (event.type == SDL_KEYDOWN)
+            return event.key.keysym.sym;
+    }
+    return 0;
+}
\ No newline at end of file

utils/gfx/gfx.h

+#ifndef _GFX_H_
+#define _GFX_H_
+
+#include <SDL2/SDL.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#define MAKE_COLOR(r, g, b) \
+    ((uint32_t)b | ((uint32_t)g << 8) | ((uint32_t)r << 16))
+
+#define COLOR_GET_B(color) (color & 0xff)
+#define COLOR_GET_G(color) ((color >> 8) & 0xff)
+#define COLOR_GET_R(color) ((color >> 16) & 0xff)
+
+#define COLOR_BLACK 0x00000000
+#define COLOR_RED 0x00FF0000
+#define COLOR_GREEN 0x0000FF00
+#define COLOR_BLUE 0x000000FF
+#define COLOR_WHITE 0x00FFFFFF
+#define COLOR_YELLOW 0x00FFFF00
+
+struct gfx_context_t
+{
+    SDL_Window *window;
+    SDL_Renderer *renderer;
+    SDL_Texture *texture;
+    uint32_t *pixels;
+    uint32_t width;
+    uint32_t height;
+};
+
+extern void gfx_putpixel(
+    struct gfx_context_t *ctxt, uint32_t column, uint32_t row, uint32_t color);
+extern void gfx_clear(struct gfx_context_t *ctxt, uint32_t color);
+extern struct gfx_context_t *gfx_create(char *text, uint32_t width, uint32_t height);
+extern void gfx_destroy(struct gfx_context_t *ctxt);
+extern void gfx_present(struct gfx_context_t *ctxt);
+extern SDL_Keycode gfx_keypressed();
+
+#endif

utils/utils.c

+#include "vec2/vec2.h"
+#include "utils.h"
+#include <math.h>
+#include <stdlib.h>
+
+coordinates_t coordinates_create(int row_, int column_)
+{
+    coordinates_t c = {.row = row_, .column = column_};
+    return c;
+}
+
+// Transform a position in the univers [x0,y0]x[x1,y1] to a screen position
+coordinates_t position_to_coordinates(int width, int height, double x0, double x1, double y0, double y1, vec2 pos)
+{
+    double dx = x1 - x0;
+    double dy = y1 - y0;
+    return coordinates_create((int)round(height * (pos.y - y0) / dy), (int)round(width * (pos.x - x0) / dx));
+}
+
+double rand_one()
+{
+    return (double)rand() / (double)RAND_MAX;
+}
+
+charge_t charge_create(double q, vec2 pos)
+{
+    charge_t c = {.q = q, .pos = pos};
+    return c;
+}
\ No newline at end of file

utils/utils.h

+#ifndef _UTILS_H_
+#define _UTILS_H_
+#include <stdint.h>
+
+const double K = 8.988e9;
+const double E = 1.602e-19;
+
+typedef struct
+{
+    uint32_t row;
+    uint32_t column;
+} coordinates_t;
+
+typedef struct
+{
+    double q;
+    vec2 pos;
+} charge_t;
+
+coordinates_t coordinates_create(int row_, int column_);
+
+// Transform a position in the univers [x0,y0]x[x1,y1] to a screen position
+coordinates_t position_to_coordinates(int width, int height, double x0, double x1, double y0, double y1, vec2 pos);
+
+double rand_one();
+
+charge_t charge_create(double q, vec2 pos);
+
+#endif
\ No newline at end of file