zinface
/
SDL
mirror of https://github.com/libsdl-org/SDL
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

examples/renderer/03-lines: Make this less obnoxious to look at.

This commit is contained in:
Ryan C. Gordon 2024-09-19 12:52:04 -04:00
parent 1b266ec13d
commit 745d5e4991
No known key found for this signature in database
GPG Key ID: FA148B892AB48044
2 changed files with 32 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
examples/renderer/03-lines/README.txt
View File

@ -1,3 +1,3 @@
This example creates an SDL window and renderer, and then draws a giant
pile of lines, in random colors, every frame.
This example creates an SDL window and renderer, and then draws a something
roughly like a Christmas tree with nothing but lines, every frame.

35
examples/renderer/03-lines/renderer-lines.c
View File

@ -1,6 +1,6 @@
/*
* This example creates an SDL window and renderer, and then draws some lines,
* rectangles and points to it every frame.
* This example creates an SDL window and renderer, and then draws some lines
* to it every frame.
*
* This code is public domain. Feel free to use it for any purpose!
*/
@ -43,16 +43,41 @@ SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
/* This function runs once per frame, and is the heart of the program. */
SDL_AppResult SDL_AppIterate(void *appstate)
{
const int num_lines = 5000;
int i;
/* Lines (line segments, really) are drawn in terms of points: a set of
X and Y coordinates, one set for each end of the line.
(0, 0) is the top left of the window, and larger numbers go down
and to the right. This isn't how geometry works, but this is pretty
standard in 2D graphics. */
static const SDL_FPoint line_points[] = {
{ 100, 354 }, { 220, 230 }, { 140, 230 }, { 320, 100 }, { 500, 230 },
{ 420, 230 }, { 540, 354 }, { 400, 354 }, { 100, 354 }
};
/* as you can see from this, rendering draws over whatever was drawn before it. */
SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); /* black, full alpha */
SDL_RenderClear(renderer); /* start with a blank canvas. */
for (i = 0; i < num_lines; i++) {
/* You can draw lines, one at a time, like these brown ones... */
SDL_SetRenderDrawColor(renderer, 127, 49, 32, 255);
SDL_RenderLine(renderer, 240, 450, 400, 450);
SDL_RenderLine(renderer, 240, 356, 400, 356);
SDL_RenderLine(renderer, 240, 356, 240, 450);
SDL_RenderLine(renderer, 400, 356, 400, 450);
/* You can also draw a series of connected lines in a single batch... */
SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
SDL_RenderLines(renderer, line_points, SDL_arraysize(line_points));
/* here's a bunch of lines drawn out from a center point in a circle. */
/* we randomize the color of each line, so it functions as animation. */
for (i = 0; i < 360; i++) {
const float size = 30.0f;
const float x = 320.0f;
const float y = 95.0f - (size / 2.0f);
SDL_SetRenderDrawColor(renderer, SDL_rand(256), SDL_rand(256), SDL_rand(256), 255);
SDL_RenderLine(renderer, SDL_rand(640), SDL_rand(480), SDL_rand(640), SDL_rand(480));
SDL_RenderLine(renderer, x, y, x + SDL_sinf(i) * size, y + SDL_cosf(i) * size);
}
SDL_RenderPresent(renderer); /* put it all on the screen! */