SDL/test/testintersections.c

/*
  Copyright (C) 1997-2022 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely.
*/

/* Simple program:  draw as many random objects on the screen as possible */

#include <stdlib.h>
#include <time.h>

#ifdef __EMSCRIPTEN__
#include <emscripten/emscripten.h>
#endif

#include <SDL3/SDL_test_common.h>

#define SWAP(typ,a,b) do{typ t=a;a=b;b=t;}while (0)
#define NUM_OBJECTS 100

static SDLTest_CommonState *state;
static int num_objects;
static SDL_bool cycle_color;
static SDL_bool cycle_alpha;
static int cycle_direction = 1;
static int current_alpha = 255;
static int current_color = 255;
static SDL_BlendMode blendMode = SDL_BLENDMODE_NONE;

int mouse_begin_x = -1, mouse_begin_y = -1;
int done;

void
DrawPoints(SDL_Renderer * renderer)
{
    int i;
    int x, y;
    SDL_Rect viewport;

    /* Query the sizes */
    SDL_RenderGetViewport(renderer, &viewport);

    for (i = 0; i < num_objects * 4; ++i) {
        /* Cycle the color and alpha, if desired */
        if (cycle_color) {
            current_color += cycle_direction;
            if (current_color < 0) {
                current_color = 0;
                cycle_direction = -cycle_direction;
            }
            if (current_color > 255) {
                current_color = 255;
                cycle_direction = -cycle_direction;
            }
        }
        if (cycle_alpha) {
            current_alpha += cycle_direction;
            if (current_alpha < 0) {
                current_alpha = 0;
                cycle_direction = -cycle_direction;
            }
            if (current_alpha > 255) {
                current_alpha = 255;
                cycle_direction = -cycle_direction;
            }
        }
        SDL_SetRenderDrawColor(renderer, 255, (Uint8) current_color,
                               (Uint8) current_color, (Uint8) current_alpha);

        x = rand() % viewport.w;
        y = rand() % viewport.h;
        SDL_RenderDrawPoint(renderer, x, y);
    }
}

#define MAX_LINES 16
int num_lines = 0;
SDL_Rect lines[MAX_LINES];
static int
add_line(int x1, int y1, int x2, int y2)
{
    if (num_lines >= MAX_LINES) {
        return 0;
    }
    if ((x1 == x2) && (y1 == y2)) {
        return 0;
    }

    SDL_Log("adding line (%d, %d), (%d, %d)\n", x1, y1, x2, y2);
    lines[num_lines].x = x1;
    lines[num_lines].y = y1;
    lines[num_lines].w = x2;
    lines[num_lines].h = y2;

    return ++num_lines;
}


void
DrawLines(SDL_Renderer * renderer)
{
    int i;
    SDL_Rect viewport;

    /* Query the sizes */
    SDL_RenderGetViewport(renderer, &viewport);

    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255);

    for (i = 0; i < num_lines; ++i) {
        if (i == -1) {
            SDL_RenderDrawLine(renderer, 0, 0, viewport.w - 1, viewport.h - 1);
            SDL_RenderDrawLine(renderer, 0, viewport.h - 1, viewport.w - 1, 0);
            SDL_RenderDrawLine(renderer, 0, viewport.h / 2, viewport.w - 1, viewport.h / 2);
            SDL_RenderDrawLine(renderer, viewport.w / 2, 0, viewport.w / 2, viewport.h - 1);
        } else {
            SDL_RenderDrawLine(renderer, lines[i].x, lines[i].y, lines[i].w, lines[i].h);
        }
    }
}

#define MAX_RECTS 16
int num_rects = 0;
SDL_Rect rects[MAX_RECTS];
static int
add_rect(int x1, int y1, int x2, int y2)
{
    if (num_rects >= MAX_RECTS) {
        return 0;
    }
    if ((x1 == x2) || (y1 == y2)) {
        return 0;
    }

    if (x1 > x2) {
        SWAP(int, x1, x2);
    }
    if (y1 > y2) {
        SWAP(int, y1, y2);
    }

    SDL_Log("adding rect (%d, %d), (%d, %d) [%dx%d]\n", x1, y1, x2, y2,
           x2 - x1, y2 - y1);

    rects[num_rects].x = x1;
    rects[num_rects].y = y1;
    rects[num_rects].w = x2 - x1;
    rects[num_rects].h = y2 - y1;

    return ++num_rects;
}

static void
DrawRects(SDL_Renderer * renderer)
{
    SDL_SetRenderDrawColor(renderer, 255, 127, 0, 255);
    SDL_RenderFillRects(renderer, rects, num_rects);
}

static void
DrawRectLineIntersections(SDL_Renderer * renderer)
{
    int i, j;

    SDL_SetRenderDrawColor(renderer, 0, 255, 55, 255);

    for (i = 0; i < num_rects; i++)
        for (j = 0; j < num_lines; j++) {
            int x1, y1, x2, y2;
            SDL_Rect r;

            r = rects[i];
            x1 = lines[j].x;
            y1 = lines[j].y;
            x2 = lines[j].w;
            y2 = lines[j].h;

            if (SDL_IntersectRectAndLine(&r, &x1, &y1, &x2, &y2)) {
                SDL_RenderDrawLine(renderer, x1, y1, x2, y2);
            }
        }
}

static void
DrawRectRectIntersections(SDL_Renderer * renderer)
{
    int i, j;

    SDL_SetRenderDrawColor(renderer, 255, 200, 0, 255);

    for (i = 0; i < num_rects; i++)
        for (j = i + 1; j < num_rects; j++) {
            SDL_Rect r;
            if (SDL_IntersectRect(&rects[i], &rects[j], &r)) {
                SDL_RenderFillRect(renderer, &r);
            }
        }
}

void
loop()
{
    int i;
    SDL_Event event;

    /* Check for events */
    while (SDL_PollEvent(&event)) {
        SDLTest_CommonEvent(state, &event, &done);
        switch (event.type) {
        case SDL_MOUSEBUTTONDOWN:
            mouse_begin_x = event.button.x;
            mouse_begin_y = event.button.y;
            break;
        case SDL_MOUSEBUTTONUP:
            if (event.button.button == 3) {
                add_line(mouse_begin_x, mouse_begin_y, event.button.x, event.button.y);
            }
            if (event.button.button == 1) {
                add_rect(mouse_begin_x, mouse_begin_y, event.button.x, event.button.y);
            }
            break;
        case SDL_KEYDOWN:
            switch (event.key.keysym.sym) {
            case 'l':
                if (event.key.keysym.mod & KMOD_SHIFT)
                    num_lines = 0;
                else
                    add_line(rand() % 640, rand() % 480, rand() % 640,
                             rand() % 480);
                break;
            case 'r':
                if (event.key.keysym.mod & KMOD_SHIFT)
                    num_rects = 0;
                else
                    add_rect(rand() % 640, rand() % 480, rand() % 640,
                             rand() % 480);
                break;
            }
            break;
        default:
            break;
        }
    }
    for (i = 0; i < state->num_windows; ++i) {
        SDL_Renderer *renderer = state->renderers[i];
        if (state->windows[i] == NULL) {
            continue;
        }
        SDL_SetRenderDrawColor(renderer, 0xA0, 0xA0, 0xA0, 0xFF);
        SDL_RenderClear(renderer);

        DrawRects(renderer);
        DrawPoints(renderer);
        DrawRectRectIntersections(renderer);
        DrawLines(renderer);
        DrawRectLineIntersections(renderer);

        SDL_RenderPresent(renderer);
    }
#ifdef __EMSCRIPTEN__
    if (done) {
        emscripten_cancel_main_loop();
    }
#endif
}

int
main(int argc, char *argv[])
{
    int i;
    Uint32 then, now, frames;

    /* Enable standard application logging */
    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);

    /* Initialize parameters */
    num_objects = NUM_OBJECTS;

    /* Initialize test framework */
    state = SDLTest_CommonCreateState(argv, SDL_INIT_VIDEO);
    if (state == NULL) {
        return 1;
    }
    for (i = 1; i < argc;) {
        int consumed;

        consumed = SDLTest_CommonArg(state, i);
        if (consumed == 0) {
            consumed = -1;
            if (SDL_strcasecmp(argv[i], "--blend") == 0) {
                if (argv[i + 1]) {
                    if (SDL_strcasecmp(argv[i + 1], "none") == 0) {
                        blendMode = SDL_BLENDMODE_NONE;
                        consumed = 2;
                    } else if (SDL_strcasecmp(argv[i + 1], "blend") == 0) {
                        blendMode = SDL_BLENDMODE_BLEND;
                        consumed = 2;
                    } else if (SDL_strcasecmp(argv[i + 1], "add") == 0) {
                        blendMode = SDL_BLENDMODE_ADD;
                        consumed = 2;
                    } else if (SDL_strcasecmp(argv[i + 1], "mod") == 0) {
                        blendMode = SDL_BLENDMODE_MOD;
                        consumed = 2;
                    }
                }
            } else if (SDL_strcasecmp(argv[i], "--cyclecolor") == 0) {
                cycle_color = SDL_TRUE;
                consumed = 1;
            } else if (SDL_strcasecmp(argv[i], "--cyclealpha") == 0) {
                cycle_alpha = SDL_TRUE;
                consumed = 1;
            } else if (SDL_isdigit(*argv[i])) {
                num_objects = SDL_atoi(argv[i]);
                consumed = 1;
            }
        }
        if (consumed < 0) {
            static const char *options[] = { "[--blend none|blend|add|mod]", "[--cyclecolor]", "[--cyclealpha]", NULL };
            SDLTest_CommonLogUsage(state, argv[0], options);
            return 1;
        }
        i += consumed;
    }
    if (!SDLTest_CommonInit(state)) {
        return 2;
    }

    /* Create the windows and initialize the renderers */
    for (i = 0; i < state->num_windows; ++i) {
        SDL_Renderer *renderer = state->renderers[i];
        SDL_SetRenderDrawBlendMode(renderer, blendMode);
        SDL_SetRenderDrawColor(renderer, 0xA0, 0xA0, 0xA0, 0xFF);
        SDL_RenderClear(renderer);
    }

    srand((unsigned int)time(NULL));

    /* Main render loop */
    frames = 0;
    then = SDL_GetTicks();
    done = 0;

#ifdef __EMSCRIPTEN__
    emscripten_set_main_loop(loop, 0, 1);
#else
    while (!done) {
        ++frames;
        loop();
    }
#endif

    SDLTest_CommonQuit(state);

    /* Print out some timing information */
    now = SDL_GetTicks();
    if (now > then) {
        double fps = ((double) frames * 1000) / (now - then);
        SDL_Log("%2.2f frames per second\n", fps);
    }
    return 0;
}

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