SDL2/test/testintersections.c

/*
  Copyright (C) 1997-2023 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>
#include <SDL3/SDL_main.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;

float mouse_begin_x = -1.0f, mouse_begin_y = -1.0f;
int done;

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

    /* Query the sizes */
    SDL_GetRenderViewport(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 = (float)(rand() % viewport.w);
        y = (float)(rand() % viewport.h);
        SDL_RenderPoint(renderer, x, y);
    }
}

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

    SDL_Log("adding line (%g, %g), (%g, %g)\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_GetRenderViewport(renderer, &viewport);

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

    for (i = 0; i < num_lines; ++i) {
        if (i == -1) {
            SDL_RenderLine(renderer, 0.0f, 0.0f, (float)(viewport.w - 1), (float)(viewport.h - 1));
            SDL_RenderLine(renderer, 0.0f, (float)(viewport.h - 1), (float)(viewport.w - 1), 0.0f);
            SDL_RenderLine(renderer, 0.0f, (float)(viewport.h / 2), (float)(viewport.w - 1), (float)(viewport.h / 2));
            SDL_RenderLine(renderer, (float)(viewport.w / 2), 0.0f, (float)(viewport.w / 2), (float)(viewport.h - 1));
        } else {
            SDL_RenderLine(renderer, lines[i].x, lines[i].y, lines[i].w, lines[i].h);
        }
    }
}

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

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

    SDL_Log("adding rect (%g, %g), (%g, %g) [%gx%g]\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++) {
            float x1, y1, x2, y2;
            SDL_FRect r;

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

            if (SDL_GetRectAndLineIntersectionFloat(&r, &x1, &y1, &x2, &y2)) {
                SDL_RenderLine(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_FRect r;
            if (SDL_GetRectIntersectionFloat(&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_EVENT_MOUSE_BUTTON_DOWN:
            mouse_begin_x = event.button.x;
            mouse_begin_y = event.button.y;
            break;
        case SDL_EVENT_MOUSE_BUTTON_UP:
            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_EVENT_KEY_DOWN:
            switch (event.key.keysym.sym) {
            case 'l':
                if (event.key.keysym.mod & SDL_KMOD_SHIFT) {
                    num_lines = 0;
                } else {
                    add_line(
                        (float)(rand() % 640),
                        (float)(rand() % 480),
                        (float)(rand() % 640),
                        (float)(rand() % 480));
                }
                break;
            case 'r':
                if (event.key.keysym.mod & SDL_KMOD_SHIFT) {
                    num_rects = 0;
                } else {
                    add_rect(
                        (float)(rand() % 640),
                        (float)(rand() % 480),
                        (float)(rand() % 640),
                        (float)(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;
    Uint64 then, now;
    Uint32 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;
}