| // Copyright 2020 The Cobalt Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| precision mediump float; |
| |
| uniform vec4 u_color; |
| |
| varying vec4 v_rcorner; |
| varying vec2 v_texcoord; |
| |
| // Return 0 if the given position is inside the rounded corner, or scale |
| // towards 1 as it goes outside a 1-pixel anti-aliasing border. |
| // |rcorner| is a vec4 representing (scaled.xy, 1 / radius.xy) with scaled.xy |
| // representing the offset of the current position in terms of radius.xy |
| // (i.e. offset.xy / radius.xy). The scaled.xy values can be negative if the |
| // current position is outside the corner start. |
| float IsOutsideRCorner(vec4 rcorner) { |
| // Estimate the distance to an implicit function using |
| // dist = f(x,y) / length(gradient(f(x,y))) |
| // For an ellipse, f(x,y) = x^2 / a^2 + y^2 / b^2 - 1. |
| highp vec2 scaled = max(rcorner.xy, 0.0); |
| highp float implicit = dot(scaled, scaled) - 1.0; |
| |
| // NOTE: To accommodate large radius values using mediump floats, rcorner.zw |
| // was scaled by kRCornerGradientScale in the vertex attribute data. |
| // Multiply inv_gradient by kRCornerGradientScale to undo that scaling. |
| const highp float kRCornerGradientScale = 16.0; |
| highp vec2 gradient = 2.0 * scaled * rcorner.zw; |
| highp float inv_gradient = kRCornerGradientScale * |
| inversesqrt(max(dot(gradient, gradient), 0.0001)); |
| |
| return clamp(0.5 + implicit * inv_gradient, 0.0, 1.0); |
| } |
| |
| uniform vec4 u_texcoord_clamp_rgba; |
| uniform sampler2D u_texture_rgba; |
| |
| #pragma array u_texcoord_clamp(u_texcoord_clamp_rgba); |
| #pragma array u_texture(u_texture_rgba); |
| |
| vec4 GetRgba() { |
| return texture2D(u_texture_rgba, |
| clamp(v_texcoord, u_texcoord_clamp_rgba.xy, u_texcoord_clamp_rgba.zw)); |
| } |
| |
| void main() { |
| float scale = IsOutsideRCorner(v_rcorner); |
| gl_FragColor = u_color * (1.0 - scale) * GetRgba(); |
| } |