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Is the vertex normal vector the same as the normal vector?
The angle that the vertex normal vector makes with the surface normal of S1 is the same as the angle between the vertex normal and the surface normal of S2. When these two surfaces are lit and shaded with Gouraud shading, the result is a smoothly shaded, smoothly rounded edge between them.
When to use vertex normals in Direct3D?
Direct3D uses the vertex normals for Gouraud shading, lighting, and texturing effects. When applying Gouraud shading to a polygon, Direct3D uses the vertex normals to calculate the angle between the light source and the surface.
How to calculate surface normal vector for triangles?
It is more likely, however, that your object is made up of triangle strips and the triangles are not coplanar. One simple way to achieve smooth shading across all the triangles in the strip is to first calculate the surface normal vector for each polygonal face with which the vertex is associated.
How are vertex normals used in Gouraud shading?
When applying Gouraud shading to a polygon, Direct3D uses the vertex normals to calculate the angle between the light source and the surface. It calculates the color and intensity values for the vertices and interpolates them for every point across all the primitive’s surfaces. Direct3D calculates the light intensity value by using the angle.
Can a vertex normal be set to equal angle?
The vertex normal can be set to make an equal angle with each surface normal. However, this method might not be efficient enough for complex primitives. This method is illustrated by the following diagram, which shows two surfaces, S1 and S2 seen edge-on from above. The normal vectors for S1 and S2 are shown in blue.
Is the normal vector for S1 the same as S2?
The normal vectors for S1 and S2 are shown in blue. The vertex normal vector is shown in red. The angle that the vertex normal vector makes with the surface normal of S1 is the same as the angle between the vertex normal and the surface normal of S2.