diff options
Diffstat (limited to 'src/imports/shapes/shaders/radialgradient.frag')
-rw-r--r-- | src/imports/shapes/shaders/radialgradient.frag | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/src/imports/shapes/shaders/radialgradient.frag b/src/imports/shapes/shaders/radialgradient.frag new file mode 100644 index 0000000000..0f503bc0f7 --- /dev/null +++ b/src/imports/shapes/shaders/radialgradient.frag @@ -0,0 +1,25 @@ +uniform sampler2D gradTabTexture; +uniform lowp float opacity; + +uniform highp vec2 focalToCenter; +uniform highp float centerRadius; +uniform highp float focalRadius; + +varying highp vec2 coord; + +void main() +{ + highp float rd = centerRadius - focalRadius; + highp float b = 2.0 * (rd * focalRadius + dot(coord, focalToCenter)); + highp float fmp2_m_radius2 = -focalToCenter.x * focalToCenter.x - focalToCenter.y * focalToCenter.y + rd * rd; + highp float inverse_2_fmp2_m_radius2 = 1.0 / (2.0 * fmp2_m_radius2); + highp float det = b * b - 4.0 * fmp2_m_radius2 * ((focalRadius * focalRadius) - dot(coord, coord)); + lowp vec4 result = vec4(0.0); + if (det >= 0.0) { + highp float detSqrt = sqrt(det); + highp float w = max((-b - detSqrt) * inverse_2_fmp2_m_radius2, (-b + detSqrt) * inverse_2_fmp2_m_radius2); + if (focalRadius + w * (centerRadius - focalRadius) >= 0.0) + result = texture2D(gradTabTexture, vec2(w, 0.5)) * opacity; + } + gl_FragColor = result; +} |