1/*
2 Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
3
4 This software is provided 'as-is', without any express or implied
5 warranty. In no event will the authors be held liable for any damages
6 arising from the use of this software.
7
8 Permission is granted to anyone to use this software for any purpose,
9 including commercial applications, and to alter it and redistribute it
10 freely.
11*/
12/* Simple program: Move N sprites around on the screen as fast as possible */
13
14#include <stdlib.h>
15#include <stdio.h>
16#include <time.h>
17
18#ifdef __EMSCRIPTEN__
19#include <emscripten/emscripten.h>
20#endif
21
22#include "SDL.h"
23
24#define WINDOW_WIDTH 640
25#define WINDOW_HEIGHT 480
26#define NUM_SPRITES 100
27#define MAX_SPEED 1
28
29static SDL_Texture *sprite;
30static SDL_Rect positions[NUM_SPRITES];
31static SDL_Rect velocities[NUM_SPRITES];
32static int sprite_w, sprite_h;
33
34SDL_Renderer *renderer;
35int done;
36
37/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
38static void
39quit(int rc)
40{
41 SDL_Quit();
42 exit(rc);
43}
44
45int
46LoadSprite(char *file)
47{
48 SDL_Surface *temp;
49
50 /* Load the sprite image */
51 temp = SDL_LoadBMP(file);
52 if (temp == NULL) {
53 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't load %s: %s\n", file, SDL_GetError());
54 return (-1);
55 }
56 sprite_w = temp->w;
57 sprite_h = temp->h;
58
59 /* Set transparent pixel as the pixel at (0,0) */
60 if (temp->format->palette) {
61 SDL_SetColorKey(temp, SDL_TRUE, *(Uint8 *) temp->pixels);
62 } else {
63 switch (temp->format->BitsPerPixel) {
64 case 15:
65 SDL_SetColorKey(temp, SDL_TRUE,
66 (*(Uint16 *) temp->pixels) & 0x00007FFF);
67 break;
68 case 16:
69 SDL_SetColorKey(temp, SDL_TRUE, *(Uint16 *) temp->pixels);
70 break;
71 case 24:
72 SDL_SetColorKey(temp, SDL_TRUE,
73 (*(Uint32 *) temp->pixels) & 0x00FFFFFF);
74 break;
75 case 32:
76 SDL_SetColorKey(temp, SDL_TRUE, *(Uint32 *) temp->pixels);
77 break;
78 }
79 }
80
81 /* Create textures from the image */
82 sprite = SDL_CreateTextureFromSurface(renderer, temp);
83 if (!sprite) {
84 SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create texture: %s\n", SDL_GetError());
85 SDL_FreeSurface(temp);
86 return (-1);
87 }
88 SDL_FreeSurface(temp);
89
90 /* We're ready to roll. :) */
91 return (0);
92}
93
94void
95MoveSprites()
96{
97 int i;
98 int window_w = WINDOW_WIDTH;
99 int window_h = WINDOW_HEIGHT;
100 SDL_Rect *position, *velocity;
101
102 /* Draw a gray background */
103 SDL_SetRenderDrawColor(renderer, 0xA0, 0xA0, 0xA0, 0xFF);
104 SDL_RenderClear(renderer);
105
106 /* Move the sprite, bounce at the wall, and draw */
107 for (i = 0; i < NUM_SPRITES; ++i) {
108 position = &positions[i];
109 velocity = &velocities[i];
110 position->x += velocity->x;
111 if ((position->x < 0) || (position->x >= (window_w - sprite_w))) {
112 velocity->x = -velocity->x;
113 position->x += velocity->x;
114 }
115 position->y += velocity->y;
116 if ((position->y < 0) || (position->y >= (window_h - sprite_h))) {
117 velocity->y = -velocity->y;
118 position->y += velocity->y;
119 }
120
121 /* Blit the sprite onto the screen */
122 SDL_RenderCopy(renderer, sprite, NULL, position);
123 }
124
125 /* Update the screen! */
126 SDL_RenderPresent(renderer);
127}
128
129void loop()
130{
131 SDL_Event event;
132
133 /* Check for events */
134 while (SDL_PollEvent(&event)) {
135 if (event.type == SDL_QUIT || event.type == SDL_KEYDOWN) {
136 done = 1;
137 }
138 }
139 MoveSprites();
140#ifdef __EMSCRIPTEN__
141 if (done) {
142 emscripten_cancel_main_loop();
143 }
144#endif
145}
146
147int
148main(int argc, char *argv[])
149{
150 SDL_Window *window;
151 int i;
152
153
154 /* Enable standard application logging */
155 SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
156
157 if (SDL_CreateWindowAndRenderer(WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer) < 0) {
158 quit(2);
159 }
160
161 if (LoadSprite("icon.bmp") < 0) {
162 quit(2);
163 }
164
165 /* Initialize the sprite positions */
166 srand(time(NULL));
167 for (i = 0; i < NUM_SPRITES; ++i) {
168 positions[i].x = rand() % (WINDOW_WIDTH - sprite_w);
169 positions[i].y = rand() % (WINDOW_HEIGHT - sprite_h);
170 positions[i].w = sprite_w;
171 positions[i].h = sprite_h;
172 velocities[i].x = 0;
173 velocities[i].y = 0;
174 while (!velocities[i].x && !velocities[i].y) {
175 velocities[i].x = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;
176 velocities[i].y = (rand() % (MAX_SPEED * 2 + 1)) - MAX_SPEED;
177 }
178 }
179
180 /* Main render loop */
181 done = 0;
182
183#ifdef __EMSCRIPTEN__
184 emscripten_set_main_loop(loop, 0, 1);
185#else
186 while (!done) {
187 loop();
188 }
189#endif
190 quit(0);
191
192 return 0; /* to prevent compiler warning */
193}
194
195/* vi: set ts=4 sw=4 expandtab: */
196