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C++で超簡単に画像出力+サンプル

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準備

"stb_image_write.h"をダウンロードして、これから作る main.cpp と同じフォルダに入れる。
後は以下のサンプルを貼り付けて実行。

以下のサンプルはC++11以降の環境で動作する。

何もない画像

main.cpp
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#include <cstddef>
#include <memory>
#include <new>

struct RGBA {
    unsigned char r, g, b, a; //赤, 緑, 青, 透過
    RGBA() = default;
    constexpr RGBA(const unsigned char r_, const unsigned char g_, const unsigned char b_, const unsigned char a_) :r(r_), g(g_), b(b_), a(a_) {}
};

int main() {

    constexpr std::size_t width{ 512 }, height{ 512 }; //幅と高さ

    std::unique_ptr<RGBA[][width]> rgba(new(std::nothrow) RGBA[height][width]);
    if (!rgba) return -1;

    stbi_write_png("picture_0.png", static_cast<int>(width), static_cast<int>(height), static_cast<int>(sizeof(RGBA)), rgba.get(), 0);
}

picture_0.png

赤いHD画像

main.cpp
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#include <cstddef>
#include <memory>
#include <new>

struct RGBA {
    unsigned char r, g, b, a; //赤, 緑, 青, 透過
    RGBA() = default;
    constexpr RGBA(const unsigned char r_, const unsigned char g_, const unsigned char b_, const unsigned char a_) :r(r_), g(g_), b(b_), a(a_) {}
};

int main() {

    constexpr std::size_t width{ 1280 }, height{ 720 }; //幅と高さ

    std::unique_ptr<RGBA[][width]> rgba(new(std::nothrow) RGBA[height][width]);
    if (!rgba) return -1;

    for (std::size_t row{}; row < height; ++row)
        for (std::size_t col{}; col < width; ++col) {
            rgba[row][col].r = 255; //赤
            rgba[row][col].g = 0;
            rgba[row][col].b = 0;
            rgba[row][col].a = 255; //不透過
        }

    stbi_write_png("picture_1.png", static_cast<int>(width), static_cast<int>(height), static_cast<int>(sizeof(RGBA)), rgba.get(), 0);
}

picture_2.png

ホワイトノイズ

main.cpp
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#include <cstddef>
#include <memory>
#include <new>
#include <random>

struct RGBA {
    unsigned char r, g, b, a; //赤, 緑, 青, 透過
    RGBA() = default;
    constexpr RGBA(const unsigned char r_, const unsigned char g_, const unsigned char b_, const unsigned char a_) :r(r_), g(g_), b(b_), a(a_) {}
};

int main() {

    constexpr std::size_t width{ 1280 }, height{ 720 }; //幅と高さ

    std::unique_ptr<RGBA[][width]> rgba(new(std::nothrow) RGBA[height][width]);
    if (!rgba) return -1;

    std::random_device rd;
    std::mt19937 mt;
    mt.seed(rd());

    std::uniform_int_distribution<> uid(0, 255);

    for (std::size_t row{}; row < height; ++row)
        for (std::size_t col{}; col < width; ++col) {
            rgba[row][col].r = uid(mt); //赤
            rgba[row][col].g = uid(mt);
            rgba[row][col].b = uid(mt);
            rgba[row][col].a = 255; //不透過
        }

    stbi_write_png("picture_2.png", static_cast<int>(width), static_cast<int>(height), static_cast<int>(sizeof(RGBA)), rgba.get(), 0);
}

picture_2.png

RPGマップ

main.cpp
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

#include <cstddef>
#include <memory>
#include <new>
#include <random>

struct RGBA {
    unsigned char r, g, b, a; //赤, 緑, 青, 透過
    RGBA() = default;
    constexpr RGBA(const unsigned char r_, const unsigned char g_, const unsigned char b_, const unsigned char a_) :r(r_), g(g_), b(b_), a(a_) {}
    constexpr bool operator&&(const RGBA& rgba_) noexcept {
        return this->r == rgba_.r && this->g == rgba_.g && this->b == rgba_.b && this->a == rgba_.a;
    }
};

int main() {

    constexpr std::size_t width{ 512 }, height{ 512 }; //幅と高さ

    std::unique_ptr<RGBA[][width]> rgba(new(std::nothrow) RGBA[height][width]);
    if (!rgba) return -1;

    std::random_device rd;
    std::mt19937 mt;
    mt.seed(rd());
    std::uniform_int_distribution<> uid(0, 255);

    std::uniform_int_distribution<> uid_probability(0, 1);
    std::uniform_int_distribution<> uid_b(0, 3);

    for (std::size_t row{}; row < height; ++row)
        for (std::size_t col{}; col < width; ++col) {
            rgba[row][col].r = 41;
            rgba[row][col].g = 40;
            rgba[row][col].b = 159;
            rgba[row][col].a = 255;
        }
    for (std::size_t row{ 1 }; row < height - 1; ++row)
        for (std::size_t col{ 1 }; col < width - 1; ++col) {
            if (uid_probability(mt)) rgba[row][col] = RGBA(41, 40, 159, 255);
            else switch (uid_b(mt))
            {
            case 0:rgba[row][col] = RGBA(101, 163, 56, 255); break;
            case 1:rgba[row][col] = RGBA(223, 203, 140, 255); break;
            case 2:rgba[row][col] = RGBA(9, 100, 5, 255); break;
            case 3:rgba[row][col] = RGBA(164, 143, 50, 255); break;
            }
        }
    for (std::size_t i{}; i < 700; ++i)
        for (std::size_t row{ 1 }; row < height - 1; ++row)
            for (std::size_t col{ 1 }; col < width - 1; ++col) {
                if ((rgba[row][col - 1] && rgba[row][col + 1]) && ((rgba[row][col + 1]) && (rgba[row - 1][col])) && (rgba[row - 1][col] && rgba[row + 1][col])) {
                    rgba[row][col] = rgba[row][col + 1];
                }
                else switch (uid_b(mt))
                {
                case 0:rgba[row][col] = rgba[row][col - 1]; break;
                case 1:rgba[row][col] = rgba[row][col + 1]; break;
                case 2:rgba[row][col] = rgba[row - 1][col]; break;
                case 3:rgba[row][col] = rgba[row + 1][col]; break;
                }
            }

    stbi_write_png("picture_3.png", static_cast<int>(width), static_cast<int>(height), static_cast<int>(sizeof(RGBA)), rgba.get(), 0);
}

picture_3.png

ソースコードのライセンス

These codes are licensed under CC0.
CC0

ソースコードは自由に使用してください。

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