45 lines
1.3 KiB
Rust
45 lines
1.3 KiB
Rust
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import float::consts::pi;
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import mat::*;
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//
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// Create a perspective projection matrix
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//
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// fov is in degrees
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// http://www.opengl.org/wiki/GluPerspective_code
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//
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pure fn perspective(fovy:float, aspectRatio:float, near:float, fa:float) -> mat4 {
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let ymax = near * tan(fovy * PI / 360.0);
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let xmax = ymax * aspectRatio;
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return frustum(-xmax, xmax, -ymax, ymax, near, far);
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}
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//
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// Define a view frustrum
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// http://www.felixgers.de/teaching/jogl/perspectiveProjection.html
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// http://www.opengl.org/wiki/GluPerspective_code
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//
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// TODO: double check algorithm
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//
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pure fn frustum(left:float, right:float, bottom:float, top:float, near:float, far:float) -> mat4 {
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let m00:float = (2*near)/(right-left);
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let m01:float = 0.0;
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let m02:float = 0.0;
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let m03:float = 0.0;
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let m10:float = 0.0;
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let m11:float = (2*near)/(top-bottom);
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let m12:float = 0.0;
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let m13:float = 0.0;
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let m20:float = (right+left)/(right-left);
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let m21:float = (top+bottom)/(top-bottom);
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let m22:float = -(far+near)/(far-near);
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let m23:float = -1.0;
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let m30:float = 0.0;
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let m31:float = 0.0;
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let m32:float = -(2*far*near)/(far-near);
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let m33:float = 0.0;
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return mat4(m00, m01, m02, m03,
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m10, m11, m12, m13,
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m20, m21, m22, m23,
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m30, m31, m32, m33);
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}
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