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test_image.c
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test_image.c
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#include "ppm.h"
#include "draw.h"
#include "math.h"
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
static int floor_i(float f)
{
return (int)(f);
}
static int round_i(float f)
{
return floor_i(f + 0.5f);
}
static float frac(float f)
{
if(f < 0) {
return 1.0f - (f - floor_i(f));
}
return f - floor_i(f);
}
static float remainder_frac(float f)
{
return 1.0f - frac(f);
}
ColorRGB color_field(Point2D point);
ColorRGB heightmap(Point2D point);
float noise_2D(int x, int y);
float smooth_noise_2D(int x, int y);
float interpolated_noise(float x, float y);
float cos_interp(float x, float y, float a);
float Perlin2D(float x, float y, float pers, int n_oct);
int main(int argc, char** argv)
{
Image* image = ppm_create(1024, 1024);
Image* smaller = ppm_create(128, 128);
int x, y;
for(y = 0; y < image->header.height; y++) {
for(x = 0; x < image->header.width; x++) {
Point2D pix = point2(x, y);
float x_scale = image->header.width / 8.0f;
float y_scale = image->header.height / 8.0f;
Point2D samp = point2((pix.x + 512) / x_scale, (pix.y + 512) / y_scale);
//ColorRGB color = color_field(samp);
ColorRGB height = heightmap(samp);
//ColorRGB blended = blend(color, height, 0.1f);
draw_point(image, pix, height);
}
}
for(y = 0; y < smaller->header.height; y++) {
for(x = 0; x < image->header.width; x++) {
Point2D pix = point2(x, y);
float x_scale = image->header.width / 8.0f;
float y_scale = image->header.height / 8.0f;
Point2D sample = point2((pix.x) / x_scale, (pix.y) / y_scale);
ColorRGB color = heightmap(sample);
draw_point(smaller, pix, color);
}
}
Rect2D src_rect, dest_rect;
src_rect = (Rect2D) { point2(0, 0), point2(smaller->header.width, smaller->header.height) };
dest_rect = (Rect2D) { point2(128, 128), point2(448, 448) };
blit_alpha(image, dest_rect, smaller, src_rect, 0.1f);
ppm_save(image, "overlay.ppm");
ppm_destroy(smaller);
ppm_destroy(image);
return 0;
}
ColorRGB heightmap(Point2D point)
{
static int init = 0;
static ColorRGB greyscale[256];
if(!init) {
int i;
for(i = 0; i < 256; i++) {
greyscale[i] = rgb(i, i, i);
}
init = 1;
}
float color_percent = Perlin2D(point.x, point.y, 0.5, 10);
if(color_percent < 0) {
color_percent = 0.0f;
}
if(color_percent > 1) {
color_percent = 1.0f;
}
color_percent *= 255;
int rounded = round_i(color_percent);
return greyscale[rounded];
}
ColorRGB color_field(Point2D point)
{
ColorRGB colors[] = {
rgb(0, 0, 64),
rgb(128, 0, 128),
rgb(128, 0, 255),
rgb(128, 64, 255),
rgb(64, 64, 255),
rgb(0, 128, 255),
rgb(0, 192, 255),
rgb(0, 255, 255),
rgb(0, 255, 128),
rgb(0, 255, 64),
rgb(64, 255, 64),
rgb(64, 255, 0),
rgb(128, 255, 0),
rgb(255, 255, 0),
rgb(255, 128, 0),
rgb(128, 0, 0),
rgb(255, 0, 0),
rgb(255, 64, 64),
rgb(255, 128, 128),
rgb(255, 192, 192),
rgb(255, 255, 255)
};
float color_percent = Perlin2D(point.x, point.y, 0.5, 10);
if(color_percent < 0) {
color_percent = 0.0f;
}
if(color_percent > 1) {
color_percent = 1.0f;
}
color_percent *= ((sizeof(colors) / sizeof(colors[0])) - 1);
int rounded = round_i(color_percent);
float alpha = frac(color_percent);
int bg, fg;
if(alpha > 0.5) {
bg = rounded - 1;
fg = rounded;
alpha = 1.0f - alpha;
} else {
bg = rounded;
fg = rounded + 1;
}
return blend(colors[bg], colors[fg], alpha);
}
float noise_2D(int x, int y)
{
int n = x + y * 57;
n = (n << 13) ^ n;
return 1.0f - ( ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7FFFFFFF) / 1073741824.0f);
}
float smooth_noise_2D(int x, int y)
{
int x0 = x-1;
int x1 = x+1;
int y0 = y-1;
int y1 = y+1;
float corners = (noise_2D(x0, y0) + noise_2D(x1, y0) + noise_2D(x0, y1) + noise_2D(x1, y1)) / 16.0f;
float sides = (noise_2D(x0, y) + noise_2D(x1, y) + noise_2D(x, y0) + noise_2D(x, y1)) / 8.0f;
float center = noise_2D(x, y);
return center + sides + corners;
}
float interpolated_noise(float x, float y)
{
int x_ = floor_i(x);
int y_ = floor_i(y);
float frac_x = frac(x);
float frac_y = frac(y);
float v1 = smooth_noise_2D(x_, y_);
float v2 = smooth_noise_2D(x_ + 1, y_);
float v3 = smooth_noise_2D(x_, y_ + 1);
float v4 = smooth_noise_2D(x_ + 1, y_ + 1);
float i1 = cos_interp(v1, v2, frac_x);
float i2 = cos_interp(v3, v4, frac_x);
return cos_interp(i1, i2, frac_y);
}
float cos_interp(float a, float b, float t)
{
float theta = t * M_PI;
float f = (1.0f - cos(theta)) * 0.5f;
return (1.0f - f) * a + f * b;
}
float Perlin2D(float x, float y, float persistence, int n_octave)
{
float total = 0;
float p = persistence;
int i;
for(i = 0; i < n_octave; i++) {
float freq = pow(2, i);
float ampl = pow(p, i);
total += interpolated_noise(x * freq, y * freq) * ampl;
}
return total;
}