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authorBrian Paul <brianp@vmware.com>2009-03-17 10:28:32 -0600
committerBrian Paul <brianp@vmware.com>2009-03-17 10:28:32 -0600
commitc334ce273e946733928339b1c7f9a02ccdef1b4b (patch)
treebcd4db01fc727f99e38f2159169cf8b1bf419da6
parent1eee1bac1f6d911e6124daafc9b9291666d91cef (diff)
swrast: use better _swrast_compute_lambda() function
The MAX-based function can produce values that are non-monotonic for a span which causes glitches in texture filtering. The sqrt-based one avoids that. This is perhaps slightly slower than before, but the difference probably isn't noticable given we're doing software mipmap filtering. Issue reported by Nir Radian <nirr@horizonsemi.com>
-rw-r--r--src/mesa/swrast/s_span.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/src/mesa/swrast/s_span.c b/src/mesa/swrast/s_span.c
index 5e1f412d6b..15a783b236 100644
--- a/src/mesa/swrast/s_span.c
+++ b/src/mesa/swrast/s_span.c
@@ -442,11 +442,10 @@ _swrast_span_interpolate_z( const GLcontext *ctx, SWspan *span )
* Compute mipmap LOD from partial derivatives.
* This the ideal solution, as given in the OpenGL spec.
*/
-#if 0
-static GLfloat
-compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
- GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
- GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
+GLfloat
+_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
+ GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
+ GLfloat s, GLfloat t, GLfloat q, GLfloat invQ)
{
GLfloat dudx = texW * ((s + dsdx) / (q + dqdx) - s * invQ);
GLfloat dvdx = texH * ((t + dtdx) / (q + dqdx) - t * invQ);
@@ -458,13 +457,13 @@ compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
GLfloat lambda = LOG2(rho);
return lambda;
}
-#endif
/**
* Compute mipmap LOD from partial derivatives.
* This is a faster approximation than above function.
*/
+#if 0
GLfloat
_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
@@ -485,6 +484,7 @@ _swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
lambda = LOG2(rho);
return lambda;
}
+#endif
/**