mirror of
https://github.com/Relintai/sdl2_frt.git
synced 2024-12-25 09:17:12 +01:00
130 lines
3.8 KiB
C
130 lines
3.8 KiB
C
/*
|
|
* touch.c
|
|
* written by Holmes Futrell
|
|
* use however you want
|
|
*/
|
|
|
|
#include "SDL.h"
|
|
#include "math.h"
|
|
#include "common.h"
|
|
|
|
#define BRUSH_SIZE 32 /* width and height of the brush */
|
|
#define PIXELS_PER_ITERATION 5 /* number of pixels between brush blots when forming a line */
|
|
|
|
static SDL_Texture *brush = 0; /* texture for the brush */
|
|
|
|
/*
|
|
draws a line from (startx, starty) to (startx + dx, starty + dy)
|
|
this is accomplished by drawing several blots spaced PIXELS_PER_ITERATION apart
|
|
*/
|
|
void
|
|
drawLine(SDL_Renderer *renderer, float startx, float starty, float dx, float dy)
|
|
{
|
|
|
|
float distance = sqrt(dx * dx + dy * dy); /* length of line segment (pythagoras) */
|
|
int iterations = distance / PIXELS_PER_ITERATION + 1; /* number of brush sprites to draw for the line */
|
|
float dx_prime = dx / iterations; /* x-shift per iteration */
|
|
float dy_prime = dy / iterations; /* y-shift per iteration */
|
|
SDL_Rect dstRect; /* rect to draw brush sprite into */
|
|
float x;
|
|
float y;
|
|
int i;
|
|
|
|
dstRect.w = BRUSH_SIZE;
|
|
dstRect.h = BRUSH_SIZE;
|
|
|
|
/* setup x and y for the location of the first sprite */
|
|
x = startx - BRUSH_SIZE / 2.0f;
|
|
y = starty - BRUSH_SIZE / 2.0f;
|
|
|
|
/* draw a series of blots to form the line */
|
|
for (i = 0; i < iterations; i++) {
|
|
dstRect.x = x;
|
|
dstRect.y = y;
|
|
/* shift x and y for next sprite location */
|
|
x += dx_prime;
|
|
y += dy_prime;
|
|
/* draw brush blot */
|
|
SDL_RenderCopy(renderer, brush, NULL, &dstRect);
|
|
}
|
|
}
|
|
|
|
/*
|
|
loads the brush texture
|
|
*/
|
|
void
|
|
initializeTexture(SDL_Renderer *renderer)
|
|
{
|
|
SDL_Surface *bmp_surface;
|
|
bmp_surface = SDL_LoadBMP("stroke.bmp");
|
|
if (bmp_surface == NULL) {
|
|
fatalError("could not load stroke.bmp");
|
|
}
|
|
brush =
|
|
SDL_CreateTextureFromSurface(renderer, bmp_surface);
|
|
SDL_FreeSurface(bmp_surface);
|
|
if (brush == 0) {
|
|
fatalError("could not create brush texture");
|
|
}
|
|
/* additive blending -- laying strokes on top of eachother makes them brighter */
|
|
SDL_SetTextureBlendMode(brush, SDL_BLENDMODE_ADD);
|
|
/* set brush color (red) */
|
|
SDL_SetTextureColorMod(brush, 255, 100, 100);
|
|
}
|
|
|
|
int
|
|
main(int argc, char *argv[])
|
|
{
|
|
|
|
int x, y, dx, dy; /* mouse location */
|
|
Uint8 state; /* mouse (touch) state */
|
|
SDL_Event event;
|
|
SDL_Window *window; /* main window */
|
|
SDL_Renderer *renderer;
|
|
int done; /* does user want to quit? */
|
|
int w, h;
|
|
|
|
/* initialize SDL */
|
|
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
|
|
fatalError("Could not initialize SDL");
|
|
}
|
|
|
|
/* create main window and renderer */
|
|
window = SDL_CreateWindow(NULL, 0, 0, 320, 480, SDL_WINDOW_BORDERLESS | SDL_WINDOW_ALLOW_HIGHDPI);
|
|
renderer = SDL_CreateRenderer(window, 0, 0);
|
|
|
|
SDL_GetWindowSize(window, &w, &h);
|
|
SDL_RenderSetLogicalSize(renderer, w, h);
|
|
|
|
/* load brush texture */
|
|
initializeTexture(renderer);
|
|
|
|
/* fill canvass initially with all black */
|
|
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
|
|
SDL_RenderClear(renderer);
|
|
SDL_RenderPresent(renderer);
|
|
|
|
done = 0;
|
|
while (!done && SDL_WaitEvent(&event)) {
|
|
switch (event.type) {
|
|
case SDL_QUIT:
|
|
done = 1;
|
|
break;
|
|
case SDL_MOUSEMOTION:
|
|
state = SDL_GetMouseState(&x, &y); /* get its location */
|
|
SDL_GetRelativeMouseState(&dx, &dy); /* find how much the mouse moved */
|
|
if (state & SDL_BUTTON_LMASK) { /* is the mouse (touch) down? */
|
|
drawLine(renderer, x - dx, y - dy, dx, dy); /* draw line segment */
|
|
SDL_RenderPresent(renderer);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* cleanup */
|
|
SDL_DestroyTexture(brush);
|
|
SDL_Quit();
|
|
|
|
return 0;
|
|
}
|