From 91de7b6cd30ad5ec00dd94ea4a56ec0c9056948f Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Thu, 17 Jul 2008 10:03:10 -0600 Subject: mesa: fix/improve the atan(y,x) function --- .../shader/slang/library/slang_common_builtin.gc | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) (limited to 'src') diff --git a/src/mesa/shader/slang/library/slang_common_builtin.gc b/src/mesa/shader/slang/library/slang_common_builtin.gc index b095a6434b..3726335471 100644 --- a/src/mesa/shader/slang/library/slang_common_builtin.gc +++ b/src/mesa/shader/slang/library/slang_common_builtin.gc @@ -401,16 +401,17 @@ vec4 atan(const vec4 y_over_x) float atan(const float y, const float x) { - if (x == 0.0) - return 0.0; - float z = atan(y / x); - if (x < 0.0) - { - if (y < 0.0) - return z - 3.141593; - return z + 3.141593; - } - return z; + float r; + if (abs(x) > 1.0e-4) { + r = atan(y / x); + if (x < 0.0) { + r = r + sign(y) * 3.141593; + } + } + else { + r = sign(y) * 1.5707965; // pi/2 + } + return r; } vec2 atan(const vec2 u, const vec2 v) -- cgit v1.2.3