c++ - Multiply vec3 with mat4 using glm -

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at moment, convert vec3 vec4, multiply matrix, , cast vec3

code:

glm::vec3 transformed = glm::vec3(matrix * glm::vec4(point, 0.0))

it works, think not way calculate it. possible apply mat4 on vec3, without casting vec4 , back?

when working opengl wise stick homogeneous coordinates. 3d space these 4d vectors fourth element equals 1. when calculations in 4 dimensional space, no conversions needed anywhere.

also note in example, lose translation may have been recorded in transformation matrix. if want keep you'll need use 1 4th element, not 0.

appendix f of red book describes how , why homogeneous coordinates used within opengl.


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