| #version 320 es |
| |
| // Copyright 2013 The Flutter Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| precision highp float; |
| |
| layout(location = 0) out vec4 fragColor; |
| |
| layout(location = 0) uniform float a; |
| |
| // For a given incident vector I and surface normal N reflect returns the reflection direction calculated as I - 2.0 * dot(N, I) * N. |
| void main() { |
| // To get [0.0, 1.0] as the output, choose [0.6, 0.8] as N, and solve for I. |
| // Since the reflection is symmetric: |
| // I’ = reflect(I) |
| // I’ = I - 2 dot(N, I) N |
| // I = I’ - 2 dot(N, I’) N |
| // N = [0.6, 0.8] |
| // I’ = [0, 1] |
| // I = [0, 1] - 2 * 0.8 [0.6, 0.8] |
| // I = [-0.96, -0.28] |
| fragColor = vec4( |
| reflect(vec2(a * -0.96, -0.28), vec2(0.6, 0.8))[0], |
| reflect(vec2(a * -0.96, -0.28), vec2(0.6, 0.8))[1], |
| 0.0, |
| 1.0 |
| ); |
| } |
