public static Channel erode4(Channel channel, float rain_amount, float vaporization, int rain_freq, int iterations)
{
Channel water_map = new Channel(channel.width, channel.height).fill(0f);
Channel water_map_diff = new Channel(channel.width, channel.height).fill(0f);
Channel height_map_diff = new Channel(channel.width, channel.height).fill(0f);
Console.Write("Hydraulic erosion 4: ");
for (int i = 0; i < iterations; i++) {
Console.Write(".");
// save frames
/*
if (channel.width > 128 && i%10 == 0) {
if (i < 10) {
channel.toLayer().saveAsPNG("erosion00" + i);
} else if (i < 100) {
channel.toLayer().saveAsPNG("erosion0" + i);
} else {
channel.toLayer().saveAsPNG("erosion" + i);
}
}
*/
// rain erodes the underlying terrain
if (i%rain_freq == 0) {
water_map.channelAdd(channel.copy().multiply(rain_amount));
}
// water and sediment transport
for (int y = 1; y < channel.height - 1; y++) {
for (int x = 1; x < channel.width - 1; x++) {
// calculate total heights and height differences
float h = channel.getPixel(x, y) + water_map.getPixel(x, y);
float h1 = channel.getPixel(x, y + 1) + water_map.getPixel(x, y + 1);
float h2 = channel.getPixel(x - 1, y) + water_map.getPixel(x - 1, y);
float h3 = channel.getPixel(x + 1, y) + water_map.getPixel(x + 1, y);
float h4 = channel.getPixel(x, y - 1) + water_map.getPixel(x, y - 1);
float d1 = h - h1;
float d2 = h - h2;
float d3 = h - h3;
float d4 = h - h4;
// calculate amount of water to transport
float total_height = 0;
float total_height_diff = 0;
int cells = 1;
if (d1 > 0) {
total_height_diff+= d1;
total_height+= h1;
cells++;
}
if (d2 > 0) {
total_height_diff+= d2;
total_height+= h2;
cells++;
}
if (d3 > 0) {
total_height_diff+= d3;
total_height+= h3;
cells++;
}
if (d4 > 0) {
total_height_diff+= d4;
total_height+= h4;
cells++;
}
if (cells == 1) {
continue;
}
float avr_height = total_height/cells;
float water_amount = Math.Min(water_map.getPixel(x, y), h - avr_height);
water_map_diff.putPixel(x, y, water_map_diff.getPixel(x, y) - water_amount);
float total_height_diff_inv = water_amount/total_height_diff;
// transport water
if (d1 > 0) {
water_amount = d1*total_height_diff_inv;
water_map_diff.putPixel(x, y + 1, water_map_diff.getPixel(x, y + 1) + water_amount);
height_map_diff.putPixel(x, y + 1, height_map_diff.getPixel(x, y + 1) - 0.1f*water_amount);
}
if (d2 > 0) {
water_amount = d2*total_height_diff_inv;
water_map_diff.putPixel(x - 1, y, water_map_diff.getPixel(x - 1, y) + water_amount);
height_map_diff.putPixel(x - 1, y, height_map_diff.getPixel(x - 1, y) - 0.1f*water_amount);
}
if (d3 > 0) {
water_amount = d3*total_height_diff_inv;
water_map_diff.putPixel(x + 1, y, water_map_diff.getPixel(x + 1, y) + water_amount);
height_map_diff.putPixel(x + 1, y, height_map_diff.getPixel(x + 1, y) - 0.1f*water_amount);
}
if (d4 > 0) {
water_amount = d4*total_height_diff_inv;
water_map_diff.putPixel(x, y - 1, water_map_diff.getPixel(x, y - 1) + water_amount);
height_map_diff.putPixel(x, y - 1, height_map_diff.getPixel(x, y - 1) - 0.1f*water_amount);
}
}
}
// apply changes to water map
water_map.channelAddNoClip(water_map_diff);
water_map_diff.fill(0f);
// apply changes to height map
channel.channelAddNoClip(height_map_diff);
height_map_diff.fill(0f);
// vaporize water
channel.channelAddNoClip(water_map.copy().channelSubtract(water_map.addClip(-vaporization)).multiply(0.5f));
}
// force evaporation of remaining water
channel.channelAdd(water_map.multiply(0.5f));
Console.WriteLine("DONE");
return channel;
}
public static Channel erode3(Channel channel, Channel rain_map, float vaporization, int rain_freq, int iterations)
{
Channel vapor_map = rain_map.copy().multiply(0.5f);
Channel height_map_diff = new Channel(channel.width, channel.height).fill(0f);
Channel water_map = new Channel(channel.width, channel.height).fill(0f);
Channel water_map_diff = new Channel(channel.width, channel.height).fill(0f);
Channel sediment_map = new Channel(channel.width, channel.height).fill(0f);
Channel sediment_map_diff = new Channel(channel.width, channel.height).fill(0f);
Console.Write("Hydraulic erosion 3: ");
for (int i = 0; i < iterations; i++) {
Console.Write(".");
// save frames
/*
if (channel.width > 128 && i%8 == 0) {
if (i < 10) {
channel.toLayer().saveAsPNG("erosion00" + i);
} else if (i < 100) {
channel.toLayer().saveAsPNG("erosion0" + i);
} else {
channel.toLayer().saveAsPNG("erosion" + i);
}
}
*/
// rain
if (i%rain_freq == 0) {
water_map.channelAdd(rain_map);
}
// water and sediment transport
for (int y = 1; y < channel.height - 1; y++) {
for (int x = 1; x < channel.width - 1; x++) {
// calculate total heights and height differences
float h = channel.getPixel(x, y) + water_map.getPixel(x, y);
float h1 = channel.getPixel(x, y + 1) + water_map.getPixel(x, y + 1) + sediment_map.getPixel(x, y + 1);
float h2 = channel.getPixel(x - 1, y) + water_map.getPixel(x - 1, y) + sediment_map.getPixel(x - 1, y);
float h3 = channel.getPixel(x + 1, y) + water_map.getPixel(x + 1, y) + sediment_map.getPixel(x + 1, y);
float h4 = channel.getPixel(x, y - 1) + water_map.getPixel(x, y - 1) + sediment_map.getPixel(x, y - 1);
float d1 = h - h1;
float d2 = h - h2;
float d3 = h - h3;
float d4 = h - h4;
// calculate amount of water and sediment to transport
float total_height = 0;
float total_height_diff = 0;
int cells = 1;
if (d1 > 0) {
total_height_diff+= d1;
total_height+= h1;
cells++;
}
if (d2 > 0) {
total_height_diff+= d2;
total_height+= h2;
cells++;
}
if (d3 > 0) {
total_height_diff+= d3;
total_height+= h3;
cells++;
}
if (d4 > 0) {
total_height_diff+= d4;
total_height+= h4;
cells++;
}
if (cells == 1) {
continue;
}
float avr_height = total_height/cells;
float water_amount = Math.Min(water_map.getPixel(x, y), h - avr_height);
water_map_diff.putPixel(x, y, water_map_diff.getPixel(x, y) - water_amount);
float water_inv = water_amount/total_height_diff;
float sediment_amount = sediment_map.getPixel(x, y);
sediment_map_diff.putPixel(x, y, sediment_map_diff.getPixel(x, y) - sediment_amount);
float sediment_inv = sediment_amount/total_height_diff;
float dissolve;
// transport water and sediment and dissolve more material
if (d1 > 0) {
water_map_diff.putPixel(x, y + 1, water_map_diff.getPixel(x, y + 1) + d1*water_inv);
dissolve = 10f*d1*water_amount;
sediment_map_diff.putPixel(x, y + 1, sediment_map_diff.getPixel(x, y + 1) + d1*sediment_inv + dissolve);
height_map_diff.putPixel(x, y + 1, height_map_diff.getPixel(x, y + 1) - dissolve);
}
if (d2 > 0) {
water_map_diff.putPixel(x - 1, y, water_map_diff.getPixel(x - 1, y) + d2*water_inv);
dissolve = 10f*d2*water_amount;
sediment_map_diff.putPixel(x - 1, y, sediment_map_diff.getPixel(x - 1, y) + d2*sediment_inv + dissolve);
height_map_diff.putPixel(x - 1, y, height_map_diff.getPixel(x - 1, y) - dissolve);
}
if (d3 > 0) {
water_map_diff.putPixel(x + 1, y, water_map_diff.getPixel(x + 1, y) + d3*water_inv);
dissolve = 10f*d3*water_amount;
sediment_map_diff.putPixel(x + 1, y, sediment_map_diff.getPixel(x + 1, y) + d3*sediment_inv + dissolve);
height_map_diff.putPixel(x + 1, y, height_map_diff.getPixel(x + 1, y) - dissolve);
}
if (d4 > 0) {
water_map_diff.putPixel(x, y - 1, water_map_diff.getPixel(x, y - 1) + d4*water_inv);
dissolve = 10f*d4*water_amount;
sediment_map_diff.putPixel(x, y - 1, sediment_map_diff.getPixel(x, y - 1) + d4*sediment_inv + dissolve);
height_map_diff.putPixel(x, y - 1, height_map_diff.getPixel(x, y - 1) - dissolve);
}
}
}
// apply changes to water map
water_map.channelAddNoClip(water_map_diff);
// apply changes to sediment map
sediment_map.channelAddNoClip(sediment_map_diff);
// apply changes to height map
channel.channelAddNoClip(height_map_diff);
// water vaporization
water_map.addClip(-vaporization);
// sedimentation
sediment_map_diff = sediment_map.copy().channelSubtract(water_map);
sediment_map.channelSubtract(sediment_map_diff);
channel.channelAddNoClip(sediment_map_diff);
// clear diff maps
water_map_diff.fill(0f);
height_map_diff.fill(0f);
sediment_map_diff.fill(0f);
}
// force evaporation of remaining water
//channel.channelAdd(water_map.multiply(0.5f));
Console.WriteLine("DONE");
return channel;
}
