scratchapixel/scratchapixel-code

Official Scratchapixel website's code repo.

See www.scratchapixel.com

scratchapixel-code's Issues

My ppm file is corrupted.

Why my image looks like that? By the way, this is not the first time I encountered situation like that.
I printed out the result (before saving) which is correct.

The above file (I only print first 10 rgb values) indicates that from line 311 to line 341 is constantly with color 59, -84, -42 however in the first screenshot we can see something else in this range.

I also did another expriments: read the ppm file and print them on the console.

I think the codes crashed halfway. Down below, 971547 is the counter of CHARs. I did the math (also we can see from the pic) 971547 is at H:316, W795. If finish well, the counter should be 1024 x 747 x 3 = 2294784.

I will also upload the codes.

// stdafx.cpp : source file that includes just the standard includes
// CPPTEST2.pch will be the pre-compiled header
// stdafx.obj will contain the pre-compiled type information

#include "stdafx.h"
#include <fstream>  
#include <iostream>
#include <string>  

// TODO: reference any additional headers you need in STDAFX.H
// and not in this file

int main123()
{
	std::ifstream infile("out_phong.ppm");

	if (!infile.is_open()) {
		std::cerr << "ERR\n";
		return 1; 
	}
 
	std::string line;
	while (std::getline(infile, line)) {
		int char_num = 0;
		for (char c : line) { 
			//if (char_num % (1024 * 3) == 0)
			//{
			//	std::cout << std::endl << (char_num/3072) << std::endl;
			//}
			if (char_num > 970752)
			{
				std::cout << (int)c << ' ';
			}
			else
			{

				if (char_num % 3072 == 0)
				{
					std::cout << char_num / 3072 << std::endl;
				}
				if (char_num % (3072) < 30)
				{
					std::cout << (int)c << ' ';
					//std::cout << std::endl;
				}
				if (char_num % (3072) == 31)
				{
					std::cout << std::endl;
				}
			}
			//std::cout << c; 
			char_num++;
		}
		std::cout << std::endl << (char_num) << std::endl;
		std::cout << std::endl; 
	}

	infile.close();
	printf("sdadasds\n");
	return 0;
}

interpolation.cpp crashes

There seems to be a number of interesting issues here:

https://github.com/scratchapixel/scratchapixel-code/blob/main/interpolation/interpolation.cpp#L183 which as of this writing is:

#define IX(size, i, j, k) ( i * j * k * size + i * j * size + i )

You're going to overflow your structure with this. Since i,j,k max is size, then the loop will stop at size^4 + size^2 + size in indexing size^3. You probably want something like this instead:

#define IX1(size, i, j, k) ( k * size * size + j * size + i )

Beyond that, there appears to be a double free error in the trilinear interpolation. This can be fixed as follows:

for (int k = 0; k < numVertices; ++k) {
   for (int j = 0; j < numVertices; ++j) {
      for (int i = 0; i < numVertices; ++i) {

Finally, the e, f, g triplet that's computed doesn't go anywhere (here: https://github.com/scratchapixel/scratchapixel-code/blob/main/interpolation/interpolation.cpp#L229), maybe you intended to write it to a file? I understand there's no simple 3D ppm format (which is kind of a crazy oversight) so perhaps just doing the slices. Is the right way. I have that in a PR I'm going to be opening shortly after this comment

Also the code https://www.scratchapixel.com/lessons/mathematics-physics-for-computer-graphics/interpolation/bilinear-filtering.html has a syntactic error:

#if 1
    float  a = c00 * (1 - tx) + c10 * tx;
    float  b = c01 * (1 - tx) + c11 * tx;
    return a * (1) - ty) + b * ty;
#else

That block won't compile. There's a parenthesis missing.