generate blue noise points

This commit is contained in:
ktyl 2023-03-01 00:12:15 +00:00
parent 67d227deed
commit 089458476f
2 changed files with 127 additions and 1 deletions

126
src/gfx.c
View File

@ -197,7 +197,7 @@ int createTextures(int width, int height, struct Shaders shaders, struct Texture
} }
// creates a noise texture in active texture 1 // creates a noise texture in active texture 1
GLuint createNoiseTexture(int width, int height) GLuint createWhiteNoiseTexture(int width, int height)
{ {
// same init steps as with a regular texture // same init steps as with a regular texture
GLuint texture; GLuint texture;
@ -230,6 +230,130 @@ GLuint createNoiseTexture(int width, int height)
return texture; return texture;
} }
void generateBlueNoisePoints(vec2* points, int m, int n)
{
vec2 firstSample = {randomFloat(), randomFloat()};
struct Candidate
{
vec2 pos;
// distance to closest point already in pattern
float distance;
};
for (int i = 0; i < n; i++)
{
// generate a bunch of candidates
int count = m * i;
struct Candidate candidates[count];
//int closest = -1;
for (int j = 0; j < count; j++)
{
struct Candidate* c = &candidates[j];
c->pos[0] = randomFloat();
c->pos[1] = randomFloat();
// the largest distance we should expect is sqrt(2),
// so pick a maximum larger than that
c->distance = 1.5;
// get the distance of the closest point already in the pattern
for (int k = 0; k < i; k++)
{
float distance = glm_vec2_distance(c->pos, points[k]);
if (distance < c->distance)
{
c->distance = distance;
//closest = k;
}
}
}
// of our candidates, now determine which of them has the furthest
// closest-distance
int furthest = -1;
float furthestDistance = 0.0;
for (int j = 0; j < count; j++)
{
if (candidates[j].distance > furthestDistance)
{
furthest = j;
furthestDistance = candidates[j].distance;
}
}
glm_vec2_copy(candidates[furthest].pos, points[i]);
}
}
GLuint createBlueNoiseTexture(int width, int height)
{
// same init steps as with a regular texture
GLuint texture;
glGenTextures(1, &texture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_REPEAT);
int channels = 4; // rgba
int length = width*height*channels;
//printf("generating %d random floats\n", length);
printf("generating blue noise\n");
float* data = (float*)malloc(length*sizeof(float));
// generate a bunch of points
int m = 100;
int n = 100;
vec2 points[n];
generateBlueNoisePoints(points, m, n);
// use those points to generate a texture
//for (int i = 0; i < length; i++)
//{
// data[i] = randomFloat();
//}
for (int i = 0; i < width*height; i++)
{
int pixelIdx = i;
int x = pixelIdx % width;
int y = pixelIdx / width;
float u = x / (float)width;
float v = y / (float)height;
vec2 pixel = {u,v};
for (int j = 0; j < n; j++)
{
float d = glm_vec2_distance(points[j], pixel);
float r = 0.01;
if (d < r)
{
data[i * channels + 2] = 1.0;
}
}
}
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA32F, width, height, 0, GL_RGBA, GL_FLOAT, data);
glBindImageTexture(0, texture, 0, GL_FALSE, 0, GL_READ_ONLY, GL_RGBA32F);
glGenerateMipmap(GL_TEXTURE_2D);
free(data);
return texture;
}
GLuint createNoiseTexture(int width, int height)
{
//return createWhiteNoiseTexture(width, height);
return createBlueNoiseTexture(width, height);
}
GLuint createWriteOnlyTexture(int width, int height) GLuint createWriteOnlyTexture(int width, int height)
{ {
GLuint texture; GLuint texture;

View File

@ -6,6 +6,8 @@
#include <SDL2/SDL.h> #include <SDL2/SDL.h>
#include <SDL2/SDL_opengl.h> #include <SDL2/SDL_opengl.h>
#include <cglm/vec2.h>
#include "io.h" #include "io.h"
#include "random.h" #include "random.h"