glm::perspective(fov, aspect, near, far);



glm::perspective creates a 4x4 perspective projection matrix that is used in a shader (typically, vertex shader) to transform points.

A few tips:

• Often, one sets up the projection transformation and does not change it during the course of a game, unless user changes the window
• Think of znear and zfar as distance from the camera
• A vertical field of view of 45 degrees is reasonable
• The aspect ratio should match the window size
• Don’t use zero for znear (use a small number like 1.0 instead)

Some OpenGL programmers combine the modelling, viewing, and projection matrices, and pass the combined matrix to the vertex shader.

mMVP = mProjectionMatrix * mViewingMatrix * mModelingMatrix

Example:
glm::mat4 mProjection = glm::perspective(45.0f, (GLfloat)width / (GLfloat)height, 1.0f, 150.0f);

This creates a viewing volume with a 45 degree field of view in the y direction (in eye coordinates) for the given window size (width, height).  The near clipping plane is 1 unit away from the camera, and far clipping plane is 150 units away.

High