| 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; |
| } |