diff options
| author | Paul Berry <[email protected]> | 2011-07-27 15:53:31 -0700 |
|---|---|---|
| committer | Paul Berry <[email protected]> | 2011-08-01 14:37:38 -0700 |
| commit | b1b4ea0b3679db0b8fddaa9663a10d4712bba3b7 (patch) | |
| tree | 37b2c030f632c42ec7e6d2dfdd00ba19122bf99a | |
| parent | d4c80f5f85c749df3fc091ff07b60ef4989fa6d9 (diff) | |
glsl: improve the accuracy of the atan(x,y) builtin function.
The previous formula for atan(x,y) returned a value of +/- pi whenever
|x|<0.0001, and used a formula based on atan(y/x) otherwise. This
broke in cases where both x and y were small (e.g. atan(1e-5, 1e-5)).
This patch modifies the formula so that it returns a value of +/- pi
whenever |x|<1e-8*|y|, and uses the formula based on atan(y/x)
otherwise.
| -rw-r--r-- | src/glsl/builtins/ir/atan | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/glsl/builtins/ir/atan b/src/glsl/builtins/ir/atan index cfecc1f1749..7b5ea13c6ba 100644 --- a/src/glsl/builtins/ir/atan +++ b/src/glsl/builtins/ir/atan @@ -54,7 +54,9 @@ ) ( (declare () float r) - (if (expression bool > (expression float abs (var_ref x)) (constant float (0.000100))) ( + (if (expression bool > + (expression float abs (var_ref x)) + (expression float * (constant float (1.0e-8)) (expression float abs (var_ref y)))) ( (assign (x) (var_ref r) (call atan ((expression float / (var_ref y) (var_ref x))))) (if (expression bool < (var_ref x) (constant float (0.000000)) ) ( (if (expression bool >= (var_ref y) (constant float (0.000000)) ) |