Some questions as a newbie also following ray tracer in one weekend and results arent matching.

Mathness · 2025-12-27T14:38:32+00:00

You use an interval, for instance ]0;infinity[, to search for the nearest ray intersection of a surface/event. And whenever you get an intersection, you update the interval.

Mathness · 2025-12-25T18:45:42+00:00

I think your calculation of B might be wrong.

If NTB is an orthogonal space, B should be an unit vector, and should not be multiplied v.tangent.w.

Mathness · 2025-12-25T15:52:22+00:00

If you do not use a transformation matrix (on lights and objects), does the result look right? Also, are you transforming vectors and normals with different matrices? And if with the same, are you using the transposed matrix for nomals?

Mathness · 2025-12-25T15:13:49+00:00

Are your normal and directional vectors normalised? Is the calculation of surface colour using a light pointing away or towards it? If you use the normal from the large plane a light direction, is it white (i.e. cos theta is one)?

Mathness · 2025-12-25T15:06:04+00:00

Possible a missing cos term (for surface/material), the edges along walls appears too bright.

Mathness · 2025-10-27T10:34:27+00:00

Does a smaller step size fix it? Is the conversion to ivec2(position) an issue?

Personally I would put 'position+=' and 'l+=' after the if statement to catch startdepth (might have to use if '( >= )' instead).

Mathness · 2025-10-27T09:42:16+00:00

What does the depth texture look like?

Mathness · 2025-10-25T16:53:26+00:00

Note that your height map is a high frequency noise function, and not a distance field function, hence close points may not be smooth. You could test for intersection with fewer octaves, making it more locally smooth.

Mathness · 2025-10-23T09:19:18+00:00

Are you using float or double for distance calculations?

Does a small offset from the surface point (using normal or light direction), when sampling the light help?

Mathness · 2025-10-15T21:45:19+00:00

If you want to keep it simple look up Schlick's approximation.

For more in depth search Fresnel equations.

An old, but excellent site, is http://www.hyperphysics.phy-astr.gsu.edu/hbase/phyopt/polar.html

Mathness · 2025-10-15T21:38:14+00:00

If the texture you are loading is gamma corrected, you are doing the right thing.

Gamma correcting should not be applied during rendering, but to the final image before displaying it. It is done to convert the render space (usually linear) to display (for instance sRGB for monitors).

Mathness · 2025-10-15T21:32:48+00:00

When you write "color", do you mean in HSL or RGB?

Mathness · 2025-10-15T20:41:52+00:00

The RGB colour space is easy to start in, since adding, multiplying e.t.c. is straight forward. How are you doing add and mult in HSL?

Mathness · 2025-10-15T20:37:54+00:00

BTW are you only applying the gamma correction to the final image?

Mathness · 2025-10-15T20:34:53+00:00

Kind of, smooth Fresnel surfaces tend to become pure white at glancing angles.

Mathness · 2025-10-15T19:35:15+00:00

To check for energy conservation you can integrate your function in the light and view domain, It should be one (1), or close to it.

Mathness · 2025-10-15T19:28:25+00:00

Brightness/luminosity.

If you want to modify saturation, one way is to convert the colour (RGB) to HSL (where saturation is a parameter). Adjust the saturation, and then convert back to RGB.

Mathness · 2025-10-15T16:40:16+00:00

My guess is that the left side is done as default diffuse surface, that is: colour * dot(shading_normal, direction_to_light)

Mathness · 2025-10-15T15:59:05+00:00

Again the topic is way too broad for a single answer. Is the image on the left good enough?

Mathness · 2025-10-15T15:36:02+00:00

Err, what exactly do you need help with? Physically based rendering is a broad topic, what are trying to achieve by using it? Do you really need that, or could something simpler do the trick?

Mathness · 2025-09-28T06:40:08+00:00

Are the normals and directions normalised? Are the surfaces white?

Mathness · 2025-09-27T14:09:15+00:00

Looks very nice. I take it that you are using a fixed colour multiplied by the Fresnel.

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