Generation of height maps based on diamond-square-algorithm in C++

2020-05-21 1953 words 10 minutes
In fact, many times we see these renderings are really amazing things, such as some terrain seems to be three-dimensional, but in fact can be generated by two-dimensional, that is, for each pixel point to give a height value, these height values constitute a column of points and can be converted into a two-dimensional image to store, when needed, the corresponding terrain can be generated from this picture.
As for the introduction, we are only concerned with using normal distribution or diamond square to assign values, terrain generator about color and normal value images we will talk about later.
Here is the code：
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#include <iostream>
#include <tchar.h>
#include <winnt.rh>

#include <sstream>
#include <random>

#include <SimpleImage.h>
#include <TextureGenerator.h>
#include <time.h>



#include <vector>

//#pragma comment(lib, "GEDUtilsd.lib")

//Declare functions
float squareStep(float* field, int x, int y, int reach, int width);
float diamondStep(float* field, int x, int y, int reach, int width);
float random(float min, float max);
//GEDUtils::SimpleImage transfer(float* field, int width);
void smoothArray(float* field, int64_t width, int64_t height);
void diamondSquare(float* field, int size, int width, float roughness);


using namespace std;

// Define a macro for easier access to a flattened 2D array
#define IDX(x, y, w) ((x) + (y) * (w))
//Define the size of an array
#define ARR_LEN(array, length){length = sizeof(array)/sizeof(array[0]);}

/*
int main()
{
    std::cout << "Hello World!\n";
}
*/

//use for debugging
void printArray(float* field, uint64_t width, uint64_t height)
{
    for (uint64_t y = 0; y < height; y++)
    {
        for (uint64_t x = 0; x < width; x++)
            std::cout << field[IDX(x, y, width)] << " ";

        std::cout << std::endl;
    }
}


int _tmain(int argc, _TCHAR* argv[]) {


    //int len;
    /*
    ARR_LEN(argv, len);
    if (argc != len) {
        throw "invalid length";
    }
    */


    cout << endl << "argc = " << argc << endl;
    cout << "Command line arguments received are:" << endl;
    for (int i = 0; i < argc; i++)
        cout << "argument " << (i + 1) << ": " << argv[i] << endl;


    if (_tcscmp(argv[1], TEXT("-r")) != 0 || _tcscmp(argv[3], TEXT("-o_height")) != 0 || _tcscmp(argv[5], TEXT("-o_color")) != 0 || _tcscmp(argv[7], TEXT("-o_normal")) != 0) {
        throw "do not match '-r' or '-o's";
    }

    //alternative way for resolution
    //std::wstringstream wsstream;
    //wsstream << argv[2];
    //int resolution;
    //wsstream >> resolution;

    int resolution = _tstoi(argv[2]);

    if (resolution <= 0) {
        throw "<= 0 for resolution";
    }

    //preparation for normal mapping
    std::default_random_engine e;
    std::normal_distribution<float> n(0, 1);

    int length = resolution * resolution;

    float* field = new float[length];

    //mapping normal distribution
    for (int y = 0; y < resolution; y++) {
        for (int x = 0; x < resolution; x++) {
            float value = n(e);
            while (value < 0.0f || value > 1.0f) {
                value = n(e);
            }

            field[IDX(x, y, resolution)] = value >= 0 ? value : -value;
        }
    }

    //name of height file
    wstring wsh(argv[4]);
    const wchar_t* cstrh = wsh.c_str();

    //name of color file
    wstring wsc(argv[6]);
    const wchar_t* cstrc = wsc.c_str();

    //name of normal file
    wstring wsn(argv[8]);
    const wchar_t* cstrn = wsn.c_str();


    //generate a texture generator
    GEDUtils::TextureGenerator texGen(L"..\\..\\..\\..\\external\\textures\\gras15.jpg", L"..\\..\\..\\..\\external\\textures\\ground02.jpg", L"..\\..\\..\\..\\external/textures/kork02.jpg", L"..\\..\\..\\..\\external\\textures\\rock1.jpg");


    try {

        //this is for normal distribution
        /*
        //copy the created normal distribution values to the heightfield
        GEDUtils::SimpleImage heightImage = GEDUtils::SimpleImage::SimpleImage((UINT)resolution, (UINT)resolution);

        for (int y = 0; y < resolution; y++) {
            for (int x = 0; x < resolution; x++) {
                heightImage.setPixel(x, y, field[IDX(x, y, resolution)]);
            }
        }


        //save the generated heightField
        if (!heightImage.save(cstrh)) {
            throw "Could not save heightField image";
        }



        // Load height image into the image test
        //GEDUtils::SimpleImage test(cstrh);

        //create a vector to store
        vector<float> vectorHeight(field, field + length);


        //this is for normal distribution
        //texGen.generateAndStoreImages(vectorHeight,resolution - 1,cstrc,cstrn);


        delete[] field;
        */


        //this is for diamond square
        int length2 = (resolution + 1) * (resolution + 1);

        float* field2 = new float[length2];

        //assign random value to the corners
        field2[IDX(0, 0, resolution + 1)] = random(0, 1);
        field2[IDX(0, resolution, resolution + 1)] = random(0, 1);
        field2[IDX(resolution, 0, resolution + 1)] = random(0, 1);
        field2[IDX(resolution, resolution, resolution + 1)] = random(0, 1);

        //give a initial roughness
        float roughness = random(0,1);

        //diamond squre
        diamondSquare(field2, resolution, resolution + 1, roughness);


        //mapping values to a smaller array
        float* field3 = new float[length];

        for (int y = 0; y < resolution; y++) {
            for (int x = 0; x < resolution; x++) {
               //field3[IDX(x, y, resolution)] = diamondHeight.getPixel(x, y);
                field3[IDX(x, y, resolution)] = field2[IDX(x , y , resolution + 1)];

            }
        }
         delete[] field2;

         //smooth array, times can be changed
         for (int i = 1; i < 100; i++) {
             smoothArray(field3, resolution, resolution);
         }


        //copy the created normal distribution values to the heightfield
        GEDUtils::SimpleImage heightImage2 = GEDUtils::SimpleImage::SimpleImage((UINT)resolution, (UINT)resolution);

        for (int y = 0; y < resolution; y++) {
            for (int x = 0; x < resolution; x++) {
                heightImage2.setPixel(x, y, field3[IDX(x, y, resolution)]);
            }
        }

        //save the generated heightField
        if (!heightImage2.save(cstrh)) {
            throw "Could not save heightField image";
        }

        //create a vector to store
        vector<float> vectorHeight2(field3, field3 + length);

        texGen.generateAndStoreImages(vectorHeight2, resolution - 1, cstrc, cstrn);

        delete[] field3;
    }
    catch (char* exception) {
        printf("Error: %s\n", exception);
    }

    //delete[] field;

    return EXIT_SUCCESS;
}



//smooth array
void smoothArray(float* field, int64_t width, int64_t height)
{
    // Allocate a temporary new array
    float* tmp_field = new float[width * height];

    for (int64_t y = 0; y < height; y++)
        for (int64_t x = 0; x < width; x++)
        {
            // Start with the value at the current position
            float value = field[IDX(x, y, width)];

            // Add values around the current position, clamped to [0, length - 1]
            value += field[IDX(min(x + 1, width - 1), y, width)];
            value += field[IDX(min(x + 1, width - 1), max(y - 1, 0ll), width)];
            value += field[IDX(x, max(y - 1, 0ll), width)];
            value += field[IDX(max(x - 1, 0ll), max(y - 1, 0ll), width)];
            value += field[IDX(max(x - 1, 0ll), y, width)];
            value += field[IDX(max(x - 1, 0ll), min(y + 1, height - 1), width)];
            value += field[IDX(x, min(y + 1, height - 1), width)];
            value += field[IDX(min(x + 1, width - 1), min(y + 1, height - 1), width)];

            // Save the computed value in the temporary array
            tmp_field[IDX(x, y, width)] = value / 9.0f;
        }

    // Copy the values of the temporary array to the array we weant to modify
    for (uint64_t y = 0; y < height; y++)
        for (uint64_t x = 0; x < width; x++)
            field[IDX(x, y, width)] = tmp_field[IDX(x, y, width)];

    // Free the memory of our temporary array
    delete[] tmp_field;
}


//body part of diamond square
void diamondSquare(float* field, int size, int width,float roughness)
{
    int half = size / 2;
    if (half < 1)
        return;

    //square steps
    for (int y = half; y < width; y += size) {
        for (int x = half; x < width; x += size) {
            field[IDX(x, y, width)] = squareStep(field, x % width, y % width, half, width); + random(-roughness,roughness);
        }
    }


    // diamond steps
    int col = 0;
    for (int y = 0; y < width; y += half)
    {
        col++;
        //If this is an odd column.
        if (col % 2 == 1) {
            for (int x = half; x < width; x += size) {

                field[IDX(x, y, width)] = diamondStep(field, x % width, y % width, half, width); + random(-roughness, roughness);
            }
        }
        else {
            for (int x = 0; x < width; x += size) {
                field[IDX(x, y, width)] = diamondStep(field, x % width, y % width, half, width); +random(-roughness, roughness);
            }
        }
    }

    //iteration on roughness
    roughness = roughness * roughness;

    diamondSquare(field, size / 2, width, roughness);
}


//reach is the distance away from the place we are seeking for average
float squareStep(float* field, int x, int y, int reach, int width)
{
    float count = 0;
    float avg = 0.;
    if (x - reach >= 0 && y - reach >= 0)
    {
        avg = avg + field[IDX(x - reach, y - reach, width)];
        count++;
    }
    if (x - reach >= 0 && y + reach < width)
    {
        avg = avg + field[IDX(x - reach, y + reach, width)];
        count++;
    }
    if (x + reach < width && y - reach >= 0)
    {
        avg = avg + field[IDX(x + reach, y - reach, width)];
        count++;
    }
    if (x + reach < width && y + reach < width)
    {
        avg =avg + field[IDX(x + reach, y + reach, width)];
        count++;
    }

    avg = avg / (float)count;

    //field[IDX(x, y, width)] = avg;
    return avg;
}


float diamondStep(float* field, int x, int y, int reach, int width)
{
    float count = 0;
    float avg = 0;
    if (x - reach >= 0)
    {
        avg = avg +  field[IDX(x - reach, y, width)];
        count++;
    }
    if (x + reach < width)
    {
        avg = avg + field[IDX(x + reach, y, width)];
        count++;
    }
    if (y - reach >= 0)
    {
        avg = avg + field[IDX(x, y - reach, width)];
        count++;
    }
    if (y + reach < width)
    {
        avg = avg + field[IDX(x, y + reach, width)];
        count++;
    }
    avg = avg / (float)count;

    return avg;
    //field[x, y, width] = avg;
}


//generate random number in a range
float random(float min, float max) {

    float random = min + (float)(rand()) / ((float)(RAND_MAX) / (max - min));
    return random;
}


/*
//store the generated field to a simple image
GEDUtils::SimpleImage transfer(float* field, int width) {
    GEDUtils::SimpleImage diamond(width - 1, width - 1);
    for (int j = 0;j < width; j++) {
        for (int i = 0; j < width; i++) {
            diamond.setPixel(i, j, field[i, j, width]);
        }
    }
    return diamond;
}
*/