Minecraft4k_SDL

// C++ port of Minecraft 4k JS (http://jsdo.it/notch/dB1E)
// By The8BitPimp
// See: the8bitpimp.wordpress.com

#include <SDL2/SDL.h>
#include <math.h>
//#include <windows.h>
//#include <tchar.h>
//#include "plot.h"
//#include "llist.h"

const int w = 320;
const int h = 240;

SDL_Window * window = nullptr;
SDL_Surface * screen = nullptr;

const float math_pi = 3.14159265359f;

static inline float math_sin(float x) {
    return sinf(x);
}

static inline float math_cos(float x) {
    return cosf(x);
}

// the texture map
int texmap[16 * 16 * 16 * 3];

// the voxel map
char map[64 * 64 * 64];

static inline int random(int max) {
    return (rand() ^ (rand() << 16)) % max;
}

static inline void plot(int x, int y, int c) {
    int *p = (int*) screen->pixels;
    p[y * w + x] = c;
}

static void makeTextures(void) {

    // each texture
    for (int j = 0; j<16; j++) {

        int k = 255 - random(96);

        // each pixel in the texture
        for (int m = 0; m<16 * 3; m++)
            for (int n = 0; n<16; n++) {

                int i1 = 0x966C4A;
                int i2 = 0;
                int i3 = 0;

                if (j == 4)
                    i1 = 0x7F7F7F;
                if ((j != 4) || (random(3) == 0))
                    k = 255 - random(96);
                if (j == 1)
                {
                    if (m < (((n * n * 3 + n * 81) >> 2) & 0x3) + 18)
                        i1 = 0x6AAA40;
                    else if (m < (((n * n * 3 + n * 81) >> 2) & 0x3) + 19)
                        k = k * 2 / 3;
                }
                if (j == 7)
                {
                    i1 = 0x675231;
                    if ((n > 0) && (n < 15) && (((m > 0) && (m < 15)) || ((m > 32) && (m < 47))))
                    {
                        i1 = 0xBC9862;
                        i2 = n - 7;
                        i3 = (m & 0xF) - 7;
                        if (i2 < 0)
                            i2 = 1 - i2;

                        if (i3 < 0)
                            i3 = 1 - i3;

                        if (i3 > i2)
                            i2 = i3;

                        k = 196 - random(32) + i2 % 3 * 32;
                    }
                    else if (random(2) == 0)
                        k = k * (150 - (n & 0x1) * 100) / 100;
                }
                if (j == 5)
                {
                    i1 = 0xB53A15;
                    if (((n + m / 4 * 4) % 8 == 0) || (m % 4 == 0))
                        i1 = 0xBCAFA5;
                }
                i2 = k;
                if (m >= 32)
                    i2 /= 2;
                if (j == 8)
                {
                    i1 = 5298487;
                    if (random(2) == 0)
                    {
                        i1 = 0;
                        i2 = 255;
                    }
                }

                // fixed point colour multiply between i1 and i2
                i3 =
                    ((((i1 >> 16) & 0xFF) * i2 / 255) << 16) |
                    ((((i1 >> 8) & 0xFF) * i2 / 255) << 8) |
                    ((i1 & 0xFF) * i2 / 255);
                // pack the colour away
                texmap[n + m * 16 + j * 256 * 3] = i3;
            }
    }
}

static void makeMap(void) {
    // add random blocks to the map
    for (int x = 0; x < 64; x++) {
        for (int y = 0; y < 64; y++) {
            for (int z = 0; z < 64; z++) {
                int i = (z << 12) | (y << 6) | x;
                float yd = (y - 32.5) * 0.4;
                float zd = (z - 32.5) * 0.4;
                map[i] = random(16);

                float th = random(256) / 256.0f;

                if (th > sqrtf(sqrtf(yd * yd + zd * zd)) - 0.8f)
                    map[i] = 0;
            }
        }
    }
}

static void init(void) {
    makeTextures();
    makeMap();
}

// fixed point byte byte multiply
static inline int fxmul(int a, int b) {
    return (a*b) >> 8;
}

// fixed point 8bit packed colour multiply
static inline int rgbmul(int a, int b) {
    int _r = (((a >> 16) & 0xff) * b) >> 8;
    int _g = (((a >> 8) & 0xff) * b) >> 8;
    int _b = (((a)& 0xff) * b) >> 8;
    return (_r << 16) | (_g << 8) | _b;
}

static void render(void) {

    float now = (float)(SDL_GetTicks() % 10000) / 10000.f;

    float xRot = math_sin(now * math_pi * 2) * 0.4 + math_pi / 2;
    float yRot = math_cos(now * math_pi * 2) * 0.4;
    float yCos = math_cos(yRot);
    float ySin = math_sin(yRot);
    float xCos = math_cos(xRot);
    float xSin = math_sin(xRot);

    float ox = 32.5 + now * 64.0;
    float oy = 32.5;
    float oz = 32.5;

    // for each column
    for (int x = 0; x < w; x++) {
        // get the x axis delta
        float ___xd = ((float)x - (float)w / 2.f) / (float)h;
        // for each row
        for (int y = 0; y < h; y++) {
            // get the y axis delta
            float  __yd = ((float)y - (float)h / 2.f) / (float)h;
            float  __zd = 1;
            float ___zd = __zd * yCos + __yd * ySin;
            float   _yd = __yd * yCos - __zd * ySin;
            float   _xd = ___xd * xCos + ___zd * xSin;
            float   _zd = ___zd * xCos - ___xd * xSin;

            int col = 0;
            int br = 255;
            float ddist = 0;

            float closest = 32.f;

            // for each principle axis  x,y,z
            for (int d = 0; d < 3; d++) {
                float dimLength = _xd;
                if (d == 1)
                    dimLength = _yd;
                if (d == 2)
                    dimLength = _zd;

                float ll = 1.0f / (dimLength < 0.f ? -dimLength : dimLength);
                float xd = (_xd)* ll;
                float yd = (_yd)* ll;
                float zd = (_zd)* ll;

                float       initial = ox - floor(ox);
                if (d == 1) initial = oy - floor(oy);
                if (d == 2) initial = oz - floor(oz);

                if (dimLength > 0) initial = 1 - initial;

                float dist = ll * initial;

                float xp = ox + xd * initial;
                float yp = oy + yd * initial;
                float zp = oz + zd * initial;

                if (dimLength < 0) {
                    if (d == 0) xp--;
                    if (d == 1) yp--;
                    if (d == 2) zp--;
                }

                // while we are concidering a ray that is still closer then the best so far
                while (dist < closest) {

                    // quantize to the map grid
                    int tex = map[(((int)zp & 63) << 12) | (((int)yp & 63) << 6) | ((int)xp & 63)];

                    // if this voxel has a texture applied
                    if (tex > 0) {

                        // find the uv coordinates of the intersection point
                        int u = ((int)((xp + zp) * 16.f)) & 15;
                        int v = ((int)(yp       * 16.f) & 15) + 16;

                        // fix uvs for alternate directions?
                        if (d == 1) {
                            u = ((int)(xp * 16.f)) & 15;
                            v = (((int)(zp * 16.f)) & 15);
                            if (yd < 0)
                                v += 32;
                        }

                        // find the colour at the intersection point
                        int cc = texmap[u + v * 16 + tex * 256 * 3];

                        // if the colour is not transparent
                        if (cc > 0) {
                            col = cc;
                            ddist = 255 - ((dist / 32 * 255));
                            br = 255 * (255 - ((d + 2) % 3) * 50) / 255;

                            // we now have the closest hit point (also terminates this ray)
                            closest = dist;
                        }
                    }

                    // advance the ray
                    xp += xd;
                    yp += yd;
                    zp += zd;
                    dist += ll;
                }
            }

            plot(x, y, rgbmul(col, fxmul(br, ddist)));
        }
    }
}

int main(int argc, char *argv[]) {

    SDL_Init(SDL_INIT_EVERYTHING);

    window = SDL_CreateWindow(
        "Minecraft4k",                  // window title
        SDL_WINDOWPOS_CENTERED,         // initial x position
        SDL_WINDOWPOS_CENTERED,         // initial y position
        320,                            // width, in pixels
        240,                            // height, in pixels
        SDL_WINDOW_OPENGL               // flags - see below
        );
    if (!window) {
        return 1;
    }

    screen = SDL_GetWindowSurface(window);
    if (!screen) {
        return 1;
    }

    init();
    bool running = true;
    while (running) {
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            running &= (event.type != SDL_QUIT);
        }
        render();
        SDL_UpdateWindowSurface(window);
    }

    SDL_DestroyWindow(window);
    SDL_Quit();
    return 0;
}