update: change buffer to double*

src/common.h

@@ -1,3 +1,5 @@
+#ifndef __COMMON_H
+#define __COMMON_H
 #include <stdio.h>
 #include <stdlib.h>
 #include <gsl/gsl_errno.h>
@@ -11,6 +13,7 @@
 #define bmin (1.5*sqrt(3.0)+5e-10)
 #define cotpsi_max (sqrt(R0*R0/(bmin*bmin*f(R0)) - 1))
 #define THETAERROR 100000
+#define color_index(i,j,c) (j*W*3+i*3+c)
 
 typedef struct {
   int W;
@@ -19,3 +22,4 @@ typedef struct {
   int (*angle_to_pixel)(double *, double *);
 } System;
 
+#endif // !__COMMON_H

src/render.c

@@ -3,6 +3,7 @@
 #include <gsl/gsl_rng.h>
 #include <gsl/gsl_spline.h>
 #include <gsl/gsl_monte_miser.h>
+#include <stdio.h>
 #include "render.h"
 
 typedef struct {
@@ -71,6 +72,7 @@ int MC_pixel_render(const System *system, int i, int j, const Spline_data spline
   gsl_monte_function F;
   F.params = &integrand_params;
   F.dim = 2;
+  printf("i=%d, j=%d, rgb=( ", i, j);
   for (int c = 0; c < 3; c++) {
     switch (c) {
       case 0:
@@ -85,8 +87,10 @@ int MC_pixel_render(const System *system, int i, int j, const Spline_data spline
     }
     gsl_monte_miser_init(miser_state);
     gsl_monte_miser_integrate(&F, xl, xu, 2, 100, r, miser_state, &color, &err);
+    printf("%g +- %g ", color, err);
     rgb[c] = color;
   }
+  printf(")\n");
 
   return 0;
 }
@@ -95,7 +99,7 @@ int pixel_render(const System *system, int i, int j, const Spline_data spline_da
   return MC_pixel_render(system, i, j, spline_data, rgb, pixel_render_max, pixel_render_err, r);
 }
 
-int render(System *system, double (*buffer)[3], int pixel_render_max, double pixel_render_err, double chi_rela_err) {
+int render(System *system, double *buffer, int pixel_render_max, double pixel_render_err, double chi_rela_err) {
   double h = (system->H)*(system->w)/(system->W);
   double tanpsi2 = (system->w)*(system->w)+h*h;
   double cotpsi2 = 1/tanpsi2;
@@ -106,6 +110,8 @@ int render(System *system, double (*buffer)[3], int pixel_render_max, double pix
   double *x=NULL;
   double *y = NULL;
   int size;
+  int W = system->W;
+  int H = system->H;
 
   init(rmax, chi_rela_err, &size, &x, &y);
 
@@ -114,9 +120,9 @@ int render(System *system, double (*buffer)[3], int pixel_render_max, double pix
   Spline_data spline_data = {spline, acc};
   gsl_spline_init(spline, x, y, size);
 
-  for(int j = 0; j < system->H; j++) {
+  for(int j = 0; j < H; j++) {
-    for (int i = 0; i < system->W; i++) {
+    for (int i = 0; i < W; i++) {
-      pixel_render(system, i, j, spline_data, buffer[j*(system->W) + i], pixel_render_max, pixel_render_err, r);
+      pixel_render(system, i, j, spline_data, buffer+color_index(i,j,0), pixel_render_max, pixel_render_err, r);
     }
   }
 

src/render.h

@@ -1,4 +1,4 @@
 #include "common.h"
 #include "init.h"
 
-int render(System *system, double (*buffer)[3], int pixel_render_max, double pixel_render_err, double chi_rela_err);
+int render(System *system, double *buffer, int pixel_render_max, double pixel_render_err, double chi_rela_err);

src/test_png.c

@@ -10,12 +10,12 @@ int angle_to_pixel_white(double *angle, double *rgb) {
 }
 
 int main(){
-  int W = 1;
+  int W = 9;
-  int H = 1;
+  int H = 9;
   double w = 1;
   System system = {W, H, w, angle_to_pixel_white};
 
-  double buffer[W*H][3];
+  double buffer[W*H*3];
 
   render(&system, buffer, 10000, 1.0/256, 1e-1);
   write_png("test_white.png", buffer, W, H);

src/write_png.c

@@ -1,7 +1,9 @@
 #include <spng.h>
 #include <math.h>
 #include <stdint.h>
+#include <stdio.h>
 #include "write_png.h"
+#include "common.h"
 
 static inline double linear_to_srgb(double x){
   if (x <= 0.0) return 0.0;
@@ -10,40 +12,43 @@ static inline double linear_to_srgb(double x){
   return 1.055 * pow(x, 1.0/2.4) - 0.055;
 }
 
-int buffer_normalize_srgb(double (*buffer)[3], int W, int H) {
+int buffer_normalize_srgb(double *buffer, int W, int H) {
   double max = 0;
   for (int j = 0; j < H; j++) {
     for (int i = 0; i < W; i++) {
       for (int c = 0; c < 3; c++) {
-        if (max < buffer[j*W + i][c]) max = buffer[j*W + i][c];
+        if (max < buffer[color_index(i, j, c)]) max = buffer[color_index(i, j, c)];
       }
     }
   }
+  printf("max in the buffer: %g\n", max);
   if (max == 0) return 1;
   for (int j = 0; j < H; j++) {
     for (int i = 0; i < W; i++) {
       for (int c = 0; c < 3; c++) {
-        buffer[j*W + i][c] /= max;
+        buffer[color_index(i, j, c)] /= max;
-        buffer[j*W+i][c] = linear_to_srgb(buffer[j*W+i][c]);
+        buffer[color_index(i, j, c)] = linear_to_srgb(buffer[color_index(i, j, c)]);
       }
     }
   }
   return 0;
 }
 
-int write_png(char *filename, double (*buffer)[3], int W, int H) {
+int write_png(char *filename, double *buffer, int W, int H) {
   buffer_normalize_srgb(buffer, W, H);
   size_t bufsize = W*H*3;
-  uint8_t *img = (uint8_t *)malloc(bufsize);
+  printf("bufsize: %d\n", bufsize);
+  uint8_t *img = (uint8_t *)malloc(bufsize*sizeof(uint8_t));
   if (!img) {return 1;}
 
   for (int j = 0; j < H; j++) {
     for (int i = 0; i < W; i++) {
       for (int c = 0; c < 3; c++) {
-        int v = (int)lrint(buffer[j*W*i][c]);
+        int v = (int)lrint(buffer[color_index(i,j,c)]*255);
         if (v < 0) v = 0;
         if (v > 255) v = 255;
-        img[j*W*3+i*3+c] = (uint8_t) v;
+        img[color_index(i, j, c)] = (uint8_t) v;
+        printf("i: %d, j: %d, c:%d, buffer=%g, v=%d\n", i,j,c,buffer[color_index(i, j, c)],v);
       }
     }
   }

src/write_png.h

@@ -1,3 +1,3 @@
+#include "common.h"
 
-
+int write_png(char *filename, double *buffer, int W, int H);
-int write_png(char *filename, double (*buffer)[3], int W, int H);