test_TerrainHydraulics.cpp

/// @file @brief This program simulates hydraulic erosion on a 2D terrain, using `TerrainHydraulics.h` to model water flow and sediment transport. It visualizes the dynamic evolution of the landscape as water carves channels and deposits material, demonstrating procedural terrain generation. The simulation can be toggled with the `SPACE` key.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <vector>
#include <math.h>

#include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h>
#include "Draw2D.h"
#include "AppSDL2OGL.h"

#include "fastmath.h"
#include "Vec2.h"
#include "geom2D.h"

#include "TerrainHydraulics.h"
#include "testUtils.h"

#include "GridIndex2D.h"
#include "Grid2DAlgs.h"
#include "SquareRuler.h"

//#include "Grid.h"

// ======================  TestApp

class TestAppTerrainHydraulics : public AppSDL2OGL{
	public:
    int job_type = 1;
    int perframe = 3;
    //TerrainHydraulics terrain;
    int shape;
    bool running = true;

    HydraulicGrid2D terrain;

	// ---- function declarations

	virtual void draw   ();
	virtual void drawHUD();
    virtual void eventHandling( const SDL_Event& event );
	//virtual int tileToList( float x0, float y0, float x1, float y1 );

    void renderMapContent ( float x0, float y0, float scale, float csc, float hsc );
    double terrain_color( int i );
	//void drawSimplexGrid( int n, float step );

	TestAppTerrainHydraulics( int& id, int WIDTH_, int HEIGHT_ );

};

double TestAppTerrainHydraulics::terrain_color( int i ){
    float g   = terrain.ground[i];
    float w   = terrain.water [i];
    if( w > g ){
        float c = (1-20*(w-g)); if(c<0) c=0;
        glColor3f(g*g*c,0.2+0.8*g*(1-g)*c,0.5);
    }else{
        glColor3f(g*g,0.2+0.8*(1-g)*g,0);
    }
    return g;
}

void TestAppTerrainHydraulics::renderMapContent( float x0, float y0, float scale, float csc, float hsc ){
    //glColor3f( 0.1f,0.1f,0.1f );
    Vec2f a,b,p;
    a.set( 1.0d, 0.0d           ); a.mul(scale);
    b.set( 0.5d, 0.86602540378d ); b.mul(scale);
    //b.set( 0.0d, 1.0 ); b.mul(scale);
    //glDisable(GL_SMOOTH);
    int ii = 0;
    for (int iy=0; iy<terrain.n.y-1; iy+=1){
    //for (int iy=0; iy<terrain.ny-1; iy+=1){
        glBegin( GL_TRIANGLE_STRIP );
        for (int ix=0; ix<terrain.n.x; ix+=1){
        //for (int ix=0; ix<terrain.nx; ix+=1){
            p.set( ix*a.x+iy*b.x + x0, ix*a.y+iy*b.y + y0 );
            //val = terrain.ground[ii              ]; w = terrain.water[ii              ];    c = csc * val;  glColor3f(c,c,w);  glVertex3f( p.x    , p.y    , val*hsc );
            //val = terrain.ground[ii + terrain.nx ]; w = terrain.water[ii + terrain.nx ];    c = csc * val;  glColor3f(c,c,w);  glVertex3f( p.x+b.x, p.y+b.y, val*hsc );

            terrain_color( ii               ); glVertex3f( p.x    , p.y    , 0 );
            terrain_color( ii + terrain.n.x  ); glVertex3f( p.x+b.x, p.y+b.y, 0 );
            //terrain_color( ii + terrain.nx  ); glVertex3f( p.x+b.x, p.y+b.y, 0 );

            //val = sin(p.x    )*sin(p.y    ); c = cscale * val;  glColor3f(c,c,c);  glVertex3f( p.x    , p.y    , val*hscale );
            //val = sin(p.x+b.x)*sin(p.y+b.y); c = cscale * val;  glColor3f(c,c,c);  glVertex3f( p.x+b.x, p.y+b.y, val*hscale );

            //glColor3f(randf(),randf(),randf()); glVertex3f( p.x    , p.y    , 0 );
            //glColor3f(randf(),randf(),randf()); glVertex3f( p.x+b.x, p.y+b.y, 0 );
            //printf( "%i, %i %f \n", iy, ix, val );
            ii++;
        }
        glEnd();
    }
}

TestAppTerrainHydraulics::TestAppTerrainHydraulics( int& id, int WIDTH_, int HEIGHT_ ) : AppSDL2OGL( id, WIDTH_, HEIGHT_ ) {
    srand(154978);
    terrain.initNeighs_6(false);
    //terrain.initNeighsSquareN(8);
    //terrain.initNeighs_6(true);
    //terrain.allocate( 512, 512 ); terrain.ground[0]=0.4; bisecNoise( 9, terrain.ground, -1.0/512, 1.0/512 );
    terrain.allocate( {512,512} ); terrain.ground[0]=0.4; bisecNoise( 9, terrain.ground, -1.0/512, 1.0/512 );
    //terrain.allocate( 512, 512 ); terrain.ground[0]=0.2; bisecPaternNoise( 9, terrain.ground, -1.0/512, 1.0/512 );
    //terrain.allocate( 512, 512 ); terrain.ground[0]=1.0; bisecNoise( 9, terrain.ground, 0, 0 );
    //terrain.allocate( 16, 16 ); bisecNoise( 4, terrain.ground, -0.5/16, 0.5/16 );
    //terrain.genTerrainNoise( 14, 0.3, 0.7, 0.6, 45454, {1000.0,1000.0} );
    //terrain.genTerrainNoise( 14, 0.5, 1.0,  0.7, 1.2, 45454, {100.0,100.0} );
    //terrain.genTerrainNoise( 8, 2.0, 1.0,  0.5, 0.8, 45454, {100.0,100.0} );

    //hydraulics.allocate(512,512); hydraulics.ground[0]=0.4; bisecNoise( 9, hydraulics.ground, -1.0/512, 1.0/512 );


/*
    shape=glGenLists(1);
	glNewList( shape, GL_COMPILE );
        renderMapContent( -0.1*terrain.nx, -0.1*terrain.ny,  0.2, 1.0, 1.0 );
	glEndList();
*/

    //for (int i=0; i<terrain.ntot; i++){  terrain.water[i] = terrain.ground[i]; }

    //for (int i=0; i<terrain.ntot; i++){  terrain.water[i] = 1.0; terrain.water_[i] = 1.0; }
    //terrain.initErrosion( 1.0 );

    shape=glGenLists(1);
}

void TestAppTerrainHydraulics::draw(){
    glClearColor( 0.5f, 0.5f, 0.5f, 0.0f );
	glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
	glDisable( GL_DEPTH_TEST );
    long t0;
    if( running ){
        t0 = getCPUticks();
        //perframe = 1;
        for( int i=0; i<perframe; i++ ){
            //terrain.errodeDroples( 10000, 100, 0.00, 0.2, 0.5 );
            for( int j=0; j<20; j++ ){
                int isz = 25;
                //int ix0 = rand()%(terrain.nx-isz);
                //int iy0 = rand()%(terrain.ny-isz);
                int ix0 = rand()%(terrain.n.x-isz);
                int iy0 = rand()%(terrain.n.y-isz);
                //terrain.errodeDroples( 200, 100, 0.02, 0.15, 0.5, ix0, iy0, ix0+isz, iy0+isz );
                terrain.errodeDroples( 200, 100, 0.02, 0.15, 0.5, {ix0, iy0}, {ix0+isz, iy0+isz} );
            }
            /*
            switch(job_type){
                case 1: {
                    int npix = terrain.flow_errosion_step_noRain( );
                    if( npix < terrain.nx ){
                        job_type = 2;
                        terrain.init_outflow();
                        for ( int ii=0; ii<50; ii++){
                            int i = rand()%terrain.ntot;
                            terrain.contour2[ii] = i;
                            terrain.nContour++;
                            terrain.water[i] = terrain.ground[i];
                        }
                        //running = false;
                    }
                    //terrain.errodeDroples( 1000, 100, 0.01 );
                    break; }
                case 2:{
                    terrain.outflow_step();
                    if( terrain.nContour == 0 ){
                        //job_type = 2;
                        running=false; break;
                    }
                    break;}
            }
            */
        }
        long tcomp = getCPUticks() - t0;
        t0    = getCPUticks();
        if( running ){
            //renderMapContent( -0.1*terrain.nx, -0.1*terrain.ny,  0.2, 1.0, 1.0 );
            renderMapContent( -0.1*terrain.n.x, -0.1*terrain.n.y,  0.2, 1.0, 1.0 );
        }else{
            glDeleteLists(shape,1);
            glNewList( shape, GL_COMPILE );
            //renderMapContent( -0.1*terrain.nx, -0.1*terrain.ny,  0.2, 1.0, 1.0 );
            renderMapContent( -0.1*terrain.n.x, -0.1*terrain.n.y,  0.2, 1.0, 1.0 );
            glEndList();
        }
        long tplot = getCPUticks() - t0;
        //printf( " tplot %3.3f Mtick tcomp %3.3f Mtick ( %3.3f ticks/pix ) \n", tplot*1e-6, tcomp*1e-6, ((double)tcomp)/(terrain.ntot*perframe) );
    }else{
        glCallList( shape );
    }
    //renderMapContent( );

};

void TestAppTerrainHydraulics::drawHUD(){}


void TestAppTerrainHydraulics::eventHandling( const SDL_Event& event ){
    switch( event.type ){
        case SDL_KEYDOWN :
            switch( event.key.keysym.sym ){
               // case SDLK_r:  terrain.initErrosion( 0.8 ); running=true;  break;
            }
            break;
         /*
        case SDL_MOUSEBUTTONDOWN:
            switch( event.button.button ){
                case SDL_BUTTON_LEFT:
                    //paintSimplex( mouse_begin_x, mouse_begin_y );
                    mouse_left  = true;
                    break;
                case SDL_BUTTON_RIGHT:
                    mouse_right = true;
                    //eraseSimplex( mouse_begin_x, mouse_begin_y );
                    break;
            }
            break;
        case SDL_MOUSEBUTTONUP:
            switch( event.button.button ){
                case SDL_BUTTON_LEFT:
                    mouse_left = false;
                    break;
                case SDL_BUTTON_RIGHT:
                    mouse_right = false;
                    break;
            }
            break;
        */
    };
    AppSDL2OGL::eventHandling( event );
};

// ===================== MAIN

TestAppTerrainHydraulics * testApp;

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

	SDL_Init(SDL_INIT_VIDEO);
	SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
	int junk;
	//testApp = new TestAppTerrainHydraulics( junk , 800, 600 );
	testApp = new TestAppTerrainHydraulics( junk , 1200, 1000 );
	testApp->loop( 1000000 );
	return 0;
}