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What do we do if we are given material node diffuse color, and color per face/vertex?
You use the most elaborate option (the color per face/vertex) as the diffuse color if you have them.
The rest of the parameters (specular, ambient) Should be taken from the material properties.
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Should we imlement clipping in this ex?
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you usually do whether you like it or not, since it's really easy to check if a point is outside the window before setting it's pixel...
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How is the vector of observtion define in a perspective projection? (for back face culling).
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You can do the backface as if it's orthographics projection
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When the user wants to use the "visible wire frame" is it supposed to be in "real time" or it supposed to be a part of the render option? as i understand it, when i push the "visible wire frame" button, nothing is supposed to change unless i push render, and then i will see the visible serface of the object with all colors plus the "visible wire frame". correct me if i'm wrong. do you exect us to impement this option as a part of the z buffer? or is there a special algorithm for this?
You are correct. the wireframe is implemented with the Z-buffer. Using the Mid-Point gives the best results.
However, there is no need for two clicks - you can render with wireframe on the "render with wireframe" click, your call.
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If I'm rendering with backface culling, and without, am I supposed to see something different or is it just supposed to work faster?
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If the object is not closed, such as an open cube or the 2planes, then surely there will be difference.
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When i am computing the direction of the normal to the polygon, how can i know the sign of the vector? how can i distinguish between two polygons that are representing by (p1,p2,p3) and one of them is facing forward and the other is facing backwards.
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You can assume one direction pre file, and add a way to swich the normal direction in case we see it's neccessary.
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I can't figure out which type of the depths of the Zbuffer we should use. is it supposed to be integer (i.e. long) or a floating point number (i.e. double)?
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Depends on the algorithm you use to render. I believe a double works well.
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Is the direction of the light source specified in View space or in Object space ? Should it move when we perform transformations ?
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The direction of the light source is specified in view space. It should not move no matter what transformations you make (and no matter in what space you make the them).
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How do we calculate the view vector ? Is it always a constant or does it change when we make transformations on the object ??? Does it change in perspective mode, or in object/view space ???
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The view vector is constant. We always look towards the X-Y plane. It should never change.
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From myself... Do u have any tips for us? (it's from 1998, not really myself...)
It's good that u asked me this, because I wanted to bring to your attention the following facts (if u don't know them yet):
When rendering with all constants as 0 (zero) except one, the colors that should be visible are:
Ambient only - the color of the object (in case of white light source). If you support multiple colored light sources, it would be nice to support the ambient light in separate...
Diffuse only - the color of the object should be visible (with shading, of course). If you support multiple colored light sources, this will surely change.
Specular only - the light color should be reflected from the object (all other parts of the objects should be black). the color of the object should not be seen!
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