100 lines
3.1 KiB
Rust
100 lines
3.1 KiB
Rust
// Copyright 2013 The Lmath Developers. For a full listing of the authors,
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// refer to the AUTHORS file at the top-level directory of this distribution.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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use mat::Mat4;
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mod num_macros;
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///
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/// Create a perspective projection matrix
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///
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/// Note: the fovy parameter should be specified in degrees.
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///
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/// This is the equivalent of the gluPerspective function, the algorithm of which
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/// can be found [here](http://www.opengl.org/wiki/GluPerspective_code).
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///
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pub fn perspective<T:Copy + Real>(fovy: T, aspectRatio: T, near: T, far: T) -> Mat4<T> {
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let ymax = near * (fovy / two!(T)).to_radians().tan();
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let xmax = ymax * aspectRatio;
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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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///
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/// This is the equivalent of the now deprecated [glFrustrum]
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/// (http://www.opengl.org/sdk/docs/man2/xhtml/glFrustum.xml) function.
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///
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pub fn frustum<T:Copy + Real>(left: T, right: T, bottom: T, top: T, near: T, far: T) -> Mat4<T> {
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let c0r0 = (two!(T) * near) / (right - left);
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let c0r1 = zero!(T);
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let c0r2 = zero!(T);
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let c0r3 = zero!(T);
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let c1r0 = zero!(T);
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let c1r1 = (two!(T) * near) / (top - bottom);
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let c1r2 = zero!(T);
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let c1r3 = zero!(T);
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let c2r0 = (right + left) / (right - left);
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let c2r1 = (top + bottom) / (top - bottom);
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let c2r2 = -(far + near) / (far - near);
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let c2r3 = -one!(T);
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let c3r0 = zero!(T);
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let c3r1 = zero!(T);
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let c3r2 = -(two!(T) * far * near) / (far - near);
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let c3r3 = zero!(T);
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Mat4::new(c0r0, c0r1, c0r2, c0r3,
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c1r0, c1r1, c1r2, c1r3,
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c2r0, c2r1, c2r2, c2r3,
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c3r0, c3r1, c3r2, c3r3)
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}
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///
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/// Create an orthographic projection matrix
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///
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/// This is the equivalent of the now deprecated [glOrtho]
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/// (http://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml) function.
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///
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pub fn ortho<T:Copy + Real>(left: T, right: T, bottom: T, top: T, near: T, far: T) -> Mat4<T> {
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let c0r0 = two!(T) / (right - left);
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let c0r1 = zero!(T);
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let c0r2 = zero!(T);
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let c0r3 = zero!(T);
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let c1r0 = zero!(T);
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let c1r1 = two!(T) / (top - bottom);
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let c1r2 = zero!(T);
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let c1r3 = zero!(T);
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let c2r0 = zero!(T);
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let c2r1 = zero!(T);
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let c2r2 = -two!(T) / (far - near);
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let c2r3 = zero!(T);
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let c3r0 = -(right + left) / (right - left);
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let c3r1 = -(top + bottom) / (top - bottom);
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let c3r2 = -(far + near) / (far - near);
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let c3r3 = one!(T);
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Mat4::new(c0r0, c0r1, c0r2, c0r3,
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c1r0, c1r1, c1r2, c1r3,
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c2r0, c2r1, c2r2, c2r3,
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c3r0, c3r1, c3r2, c3r3)
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}
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