Commit: 267e816b9a603026d951f8e8e318ceaed04ca944
Author: Germano
Date: Tue Mar 6 19:27:43 2018 -0300
Branches: blender2.8
https://developer.blender.org/rB267e816b9a603026d951f8e8e318ceaed04ca944
Draw Manager: Simplify the algorithm that extract the BoundingSphere of a
Frustum
The idea is to separate the most common case from symmetrical frustum. And to
make a simple but efficient calculation.
The new radius is usually 98% the size of the radius size of the asymmetric
solution.
Thanks to @fclem for reviewing the patch on IRC
===================================================================
M source/blender/draw/intern/draw_manager_exec.c
===================================================================
diff --git a/source/blender/draw/intern/draw_manager_exec.c
b/source/blender/draw/intern/draw_manager_exec.c
index 7b97709d51b..a984a0b782f 100644
--- a/source/blender/draw/intern/draw_manager_exec.c
+++ b/source/blender/draw/intern/draw_manager_exec.c
@@ -420,15 +420,57 @@ static void draw_clipping_setup_from_view(void)
}
/* Extract Bounding Sphere */
- /**
- * Compute bounding sphere for the general case and not only symmetric
frustum:
- * We put the sphere center on the line that goes from origin to the
center of the far clipping plane.
- * This is the optimal position if the frustum is symmetric or very
asymmetric and probably close
- * to optimal for the general case. The sphere center position is
computed so that the distance to
- * the near and far extreme frustum points are equal.
- **/
- if (projmat[3][3] == 0.0f) {
- /* Perspective */
+ if (projmat[3][3] != 0.0f) {
+ /* Orthographic */
+ /* The most extreme points on the near and far plane.
(normalized device coords). */
+ float *nearpoint = bbox.vec[0];
+ float *farpoint = bbox.vec[6];
+
+ mul_project_m4_v3(projinv, nearpoint);
+ mul_project_m4_v3(projinv, farpoint);
+
+ /* just use median point */
+ mid_v3_v3v3(bsphere->center, farpoint, nearpoint);
+ bsphere->radius = len_v3v3(bsphere->center, farpoint);
+ }
+ else if (projmat[2][0] == 0.0f && projmat[2][1] == 0.0f) {
+ /* Perspective with symmetrical frustum. */
+
+ /* We obtain the center and radius of the circumscribed circle
of the
+ * isosceles trapezoid composed by the diagonals of the near
and far clipping plane */
+
+ /* center of each clipping plane */
+ float mid_min[3], mid_max[3];
+ mid_v3_v3v3(mid_min, bbox.vec[3], bbox.vec[4]);
+ mid_v3_v3v3(mid_max, bbox.vec[2], bbox.vec[5]);
+
+ /* square length of the diagonals of each clipping plane */
+ float a_sq = len_squared_v3v3(bbox.vec[3], bbox.vec[4]);
+ float b_sq = len_squared_v3v3(bbox.vec[2], bbox.vec[5]);
+
+ /* distance squared between clipping planes */
+ float h_sq = len_squared_v3v3(mid_min, mid_max);
+
+ float fac = (4 * h_sq + b_sq - a_sq) / (8 * h_sq);
+ BLI_assert(fac >= 0.0f);
+
+ /* The goal is to get the smallest sphere,
+ * not the sphere that passes through each corner */
+ if (fac > 1.0f) {
+ fac = 1.0f;
+ }
+
+ interp_v3_v3v3(bsphere->center, mid_min, mid_max, fac);
+
+ /* distance from the center to one of the points of the far
plane (1, 2, 5, 6) */
+ bsphere->radius = len_v3v3(bsphere->center, bbox.vec[1]);
+ }
+ else {
+ /* Perspective with asymmetrical frustum. */
+
+ /* We put the sphere center on the line that goes from origin
+ * to the center of the far clipping plane. */
+
/* Detect which of the corner of the far clipping plane is the
farthest to the origin */
float nfar[4]; /* most extreme far point in NDC space */
float farxy[2]; /* farpoint projection onto the near plane
*/
@@ -483,24 +525,10 @@ static void draw_clipping_setup_from_view(void)
bsphere->center[1] = farcenter[1] * z/e;
bsphere->center[2] = z;
bsphere->radius = len_v3v3(bsphere->center, farpoint);
- }
- else {
- /* Orthographic */
- /* The most extreme points on the near and far plane.
(normalized device coords) */
- float nearpoint[3] = {-1.0f, -1.0f, -1.0f};
- float farpoint[3] = { 1.0f, 1.0f, 1.0f};
- mul_project_m4_v3(projinv, nearpoint);
- mul_project_m4_v3(projinv, farpoint);
-
- /* just use median point */
- mid_v3_v3v3(bsphere->center, farpoint, nearpoint);
- bsphere->radius = len_v3v3(bsphere->center, farpoint);
+ /* Transform to world space. */
+ mul_m4_v3(viewinv, bsphere->center);
}
-
- /* Transform to world space. */
- mul_m4_v3(viewinv, bsphere->center);
-
}
/* Return True if the given BoundSphere intersect the current view frustum */
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