https://bugs.documentfoundation.org/show_bug.cgi?id=146505
Armin Le Grand <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |NOTABUG --- Comment #2 from Armin Le Grand <[email protected]> --- ShadeMode just influences how the normals of the facets are used to determine lighting, together with the light definition. All follows pretty straightforward the basic definitions for 3D graphics rendering as in the literature. Light: We only have ambient light (all places, always, 'surrounding' light) and eight lamps with a direction, *no* position. ShadeMode Flat: For each triangle, a single normal facing away from the plane defined by the surface is used to calculate a single color for the triangle/plane. ShadeMode Gouraud: For each triangle, in all edges a normal is calculated, maybe combined with the normals of neighboring planes (as in the example). Thus, three colors are calculated and interpolated linearly while drawing the pixels. ShadeMode Phong: The same normals as for Gouraud are calculated, but during paint the *normal* is interpolated, thus allowing light calculation at each point of the surface, thus creating the specular spot light being 'realistic' in being at the center of a defined triangle - *if* the normals bend 'outwards'. These modes get more expensive from top to bottom in this order. When making triangles smaller by splitting geometry, Gouraud will get closer and closer to Phong. With each triangle representing just a pixel, it will be the same (both will then calculate one lighting per pixel). Thus, for Gouraud, no spot light is intended in general. That's why phong is there. As described, Gouraud *can* get close to Phong depending on how close the normals are to the light's direction & how small the triangles are. All works as defined. You may also just g**gle for 'Gouraud' and 'Phong' in literature to get more precise definitions. All works as defined, so no error. Note: More modern 3D engines use more modern lighting models, but that's not what we have. -- You are receiving this mail because: You are the assignee for the bug.
