diff options
Diffstat (limited to '3rdparty/bgfx/examples/41-tess/fcull.sh')
-rw-r--r-- | 3rdparty/bgfx/examples/41-tess/fcull.sh | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/3rdparty/bgfx/examples/41-tess/fcull.sh b/3rdparty/bgfx/examples/41-tess/fcull.sh new file mode 100644 index 00000000000..d44280ba23b --- /dev/null +++ b/3rdparty/bgfx/examples/41-tess/fcull.sh @@ -0,0 +1,66 @@ +bool frustumCullingTest(mat4 mvp, vec3 bmin, vec3 bmax); + +struct Frustum +{ + vec4 planes[6]; +}; + +/** + * Extract Frustum Planes from MVP Matrix + * + * Based on "Fast Extraction of Viewing Frustum Planes from the World- + * View-Projection Matrix", by Gil Gribb and Klaus Hartmann. + * This procedure computes the planes of the frustum and normalizes + * them. + */ +void loadFrustum(out Frustum f, mat4 mvp) +{ + for (int i = 0; i < 3; ++i) + { + for (int j = 0; j < 2; ++j) + { + f.planes[i*2+j].x = mtxGetElement(mvp, 0, 3) + (j == 0 ? mtxGetElement(mvp, 0, i) : -mtxGetElement(mvp, 0, i)); + f.planes[i*2+j].y = mtxGetElement(mvp, 1, 3) + (j == 0 ? mtxGetElement(mvp, 1, i) : -mtxGetElement(mvp, 1, i)); + f.planes[i*2+j].z = mtxGetElement(mvp, 2, 3) + (j == 0 ? mtxGetElement(mvp, 2, i) : -mtxGetElement(mvp, 2, i)); + f.planes[i*2+j].w = mtxGetElement(mvp, 3, 3) + (j == 0 ? mtxGetElement(mvp, 3, i) : -mtxGetElement(mvp, 3, i)); + f.planes[i*2+j]*= length(f.planes[i*2+j].xyz); + } + } +} + +/** + * Negative Vertex of an AABB + * + * This procedure computes the negative vertex of an AABB + * given a normal. + * See the View Frustum Culling tutorial @ LightHouse3D.com + * http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-testing-boxes-ii/ + */ +vec3 negativeVertex(vec3 bmin, vec3 bmax, vec3 n) +{ + bvec3 b = greaterThan(n, vec3(0.0, 0.0, 0.0)); + return mix(bmin, bmax, b); +} + +/** + * Frustum-AABB Culling Test + * + * This procedure returns true if the AABB is either inside, or in + * intersection with the frustum, and false otherwise. + * The test is based on the View Frustum Culling tutorial @ LightHouse3D.com + * http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-testing-boxes-ii/ + */ +bool frustumCullingTest(mat4 mvp, vec3 bmin, vec3 bmax) +{ + float a = 1.0f; + Frustum f; + + loadFrustum(f, mvp); + for (int i = 0; i < 6 && a >= 0.0f; ++i) + { + vec3 n = negativeVertex(bmin, bmax, f.planes[i].xyz); + a = dot(vec4(n, 1.0f), f.planes[i]); + } + + return (a >= 0.0); +} |