From 48d275a01baaff68a0c055dd77664b5d0f22d70d Mon Sep 17 00:00:00 2001
From: Andreas Grois <andi@grois.info>
Date: Sat, 10 Mar 2018 00:14:46 +0100
Subject: Dump result to image.png in current folder.

---
 BuddhaTest/src/Helpers.cpp | 64 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

(limited to 'BuddhaTest/src/Helpers.cpp')

diff --git a/BuddhaTest/src/Helpers.cpp b/BuddhaTest/src/Helpers.cpp
index e9caba9..69dafa3 100644
--- a/BuddhaTest/src/Helpers.cpp
+++ b/BuddhaTest/src/Helpers.cpp
@@ -3,6 +3,7 @@
 #include <fstream>
 #include <sstream>
 #include <vector>
+#include <png.h>
 
 namespace Helpers
 {
@@ -146,4 +147,67 @@ namespace Helpers
 		glDeleteShader(ComputeShaderID);
 		return ProgramID;
 	}
+    void WriteOutputPNG(const std::vector<uint32_t>& data, unsigned int width, unsigned int height)
+    {
+        png_byte ** row_pointers = static_cast<png_byte **>(calloc(height,sizeof(void *)));
+        for(int i = 0; i < height ; ++i)
+        {
+            row_pointers[i] = static_cast<png_byte *>(calloc(3*width,sizeof(png_byte)));
+        }
+
+        uint32_t maxValue{UINT32_C(0)};
+        for(unsigned int i = 0; i < data.size();++i)
+        {
+            maxValue = std::max(maxValue,data[i]);
+        }
+        for(unsigned int i = 0; i < data.size();++i)
+        {
+            unsigned int row = (i)/(3*width);
+            unsigned int col = i - 3*row*width;
+            row_pointers[row][col] = (255*data[i] + (maxValue/2))/maxValue;
+        }
+
+        //beware, this is going to be ugly C syntax, but well, libpng...
+        FILE * fp = fopen("image.png", "wb");
+        if(!fp)
+        {
+            return;
+        }
+        png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
+        if(!png_ptr)
+        {
+            fclose(fp);
+            return;
+        }
+        png_infop info_ptr = png_create_info_struct(png_ptr);
+        if(!info_ptr)
+        {
+            png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
+            fclose(fp);
+            return;
+        }
+        if(setjmp(png_jmpbuf(png_ptr)))
+        {
+            png_destroy_write_struct(&png_ptr, &info_ptr);
+            fclose(fp);
+            return;
+        }
+        png_init_io(png_ptr, fp);
+        png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+        png_write_info(png_ptr, info_ptr);
+        //header written.
+
+        png_write_image(png_ptr, row_pointers);
+
+        png_write_end(png_ptr, info_ptr);
+        png_destroy_write_struct(&png_ptr, &info_ptr);
+
+        for(int i = 0; i < height ; ++i)
+        {
+            free(row_pointers[i]);
+        }
+
+        free(row_pointers);
+    }
 }
-- 
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