Not sure if I should post this here or on the Math forum, but I will try my luck.
Some background. I made my custom raytracer. The processing happens purely on the CPU for now, no GPU interaction whatsoever. It supports basic Phong shading and X levels of reflections.
I started fiddling with some ideas now and I realized that I need a way to display debug lines so that I could debug what I am doing, at least to some extent.
I thought of this solution: Debug line is a constrained plane, which means that it is basically a rectangle, with pixels having their normal always facing the camera. The line is defined by a start point, magnitude, direction, and thickness. Based on these properties I should be able to calculate everything I need to get it displayed.
Below is some pseudocode for checking if my ray is intersecting this debug line.
Defined in the line initialization are:
- startPosition (where the line starts)
- magnitude (lenght of the line)
- direction (line direction)
- thickness (thickness of the line)
function isIntersecting(_originRay, _rayOrigin) ray = _originRay.Normalize(); // Ray coming from the camera spreadVector = direction.Cross(ray).Normalize(); // Vector showing the line width direction lineNormal = ray * (-1); // Debug line pixel always faces the camera directly // Plane intersection denominator = ray.Dot(lineNormal); if (denominator > 0) // Plane not visible return false; hitDistance = (startPosition - _rayOrigin).Dot(lineNormal) / denominator; hitPosition = _rayOrigin + (ray * hitDistance); // Get the intersection point in 3D space widthVector = spreadVector * thickness; hitPositionTranslated = hitPosition - startPosition; if (hitPositionTranslated.Dot(widthVector) > widthVector.Length() || hitPositionTranslated.Dot(widthVector) < 0) // Ray hitting the plane outside the constrained area return false; // Code for checking height here - Not putting it cause width is not working at first place return true;
I get this when using pretty great width (should be ~100px), but it is thin - looks like the algorithm is not constraining the width correctly:
I am obviously doing something wrong here. Any kind of help would be much appreciated!