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How is the attenuation and Spotlight factor calculated?
The attenuation value is multiplied by the red, green, and blue components of the light’s color to scale the light’s intensity as a factor of the distance light travels to a vertex. The following equation specifies the spotlight factor.
How to find the exponent of an equation?
For x n = y; solve for n by taking the log of both sides of the equation: Take the log of both sides: Dividing both sides by log x: For the equation 3 n = 81 where 3 is called the base and n is called the exponent, find the value of the exponent n using logarithms.
How to calculate the spotlight factor in Direct3D?
The following equation specifies the spotlight factor. After computing the light attenuation, Direct3D also considers spotlight effects if applicable, the angle that the light reflects from a surface, and the reflectance of the current material to calculate the diffuse and specular components for that vertex. For more information, see SpotLight.
How is the sine of the cone angle calculated?
From trigonometry, the sine of the cone angle mu is equal to the ratio of a and v : But the ratio of v to a is the Mach number of the flow. With a little algebra, we can determine that the cone angle mu is equal to the inverse sin of one over the Mach number. where asin is the trigonometric inverse sine function .
How do you apply spot attenuation in getotherlight?
And apply the spot attenuation in GetOtherLight. We start by simply using the saturated dot product of the spot and the light direction. That will attenuate the light so it reaches zero at a 90° spot angle, illuminating everything in front of the light.
How to apply spot attenuation in a shader?
We can use the negated third column of the local-to-world matrix for this, similar to directional lights. Then include a case for spot lights in the SetupLights loop. On the shader side, add the new data to the buffer in Light. And apply the spot attenuation in GetOtherLight.
Why does a spot light have an angle?
Spot lights have an angle to control how wide their light cone is. This angle is measured from its middle, so a 90° angle would look like what we have right now. Besides that, there’s also a separate inner angle that controls when the light starts attenuating.