# Questions tagged [geometry]

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### Why is the transposed inverse of the model view matrix used to transform the normal vectors?

When rendering 3D scenes with transformations applied to the objects, normals have to be transformed with the transposed inverse of the model view matrix. So, with a normal $n$, modelViewMatrix $M$, ...
• 1,220
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### How to Calculate Surface Normals for Generated Geometry

I have a class that generates a 3D shape based on inputs from the calling code. The inputs are things like length, depth, arc, etc. My code generates the geometry perfectly, however I am running into ...
• 243
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### What's the difference between geometric surface normal and shading surface normal?

In my opinion, geometric surface normal is the cross product of triangle edge vectors, and shading surface normal is the interpolation of the predefined normals at the three vertexes. I used Mitsuba ...
• 551
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### How to convert Euler angles to Quaternions and get the same Euler angles back from Quaternions?

I am rotating n 3D shape using Euler angles in the order of XYZ meaning that the object is first rotated along the X axis, then Y...
• 241
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### What formula or algorithm can I use to draw a 3D Sphere without using OpenGL? [closed]

I know that there are 3 techniques to draw 3D objects: (1) Wireframe Modeling and rendering (2) Additive Modeling (3) Subtractive Modeling Am I correct? What formula or algorithm can I use to draw a ...
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### How should I fill a shape consisting of Bezier curves and straight lines?

I have been working on a graphics library for some time now and have gotten to the point where I have to draw Bezier and line based fonts. Up to this point I am stuck with this: The green lines are ...
• 83
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### intersection between line segments - narrowed precondition

I believe that the issue may already have been discussed here. I want to find if two line segments does intersect and if they do then find and store and intesection points. Now it is already confirmed ...
• 1,029
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