epochryphon/enter_the_fog
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

transfered from codeberg

Browse Source
This commit is contained in:
epochryphon
2026-03-26 14:46:39 -05:00
parent 630f28bb7e
commit 5ed2173793
136 changed files with 14932 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

112
source_code/frustum_module/frustum/frustum.c Normal file
View File

@@ -0,0 +1,112 @@
#include "frustum.h"
#include "_internal/private_frustum.h"
#include <math.h>
#include <stdint.h>
/**
* Extracts the six clipping planes from a combined View-Projection matrix.
* * This function utilizes the Gribb-Hartmann method to derive plane equations
* directly from the matrix rows. The resulting planes are normalized to ensure
* that the distance calculations in visibility tests are accurate.
*/
void extract_frustum_planes(frustum_plane_struct planes[number_of_planes],
Matrix view_projection)
{
/* Left Clipping Plane */
planes[left].normal.x = view_projection.m3 + view_projection.m0;
planes[left].normal.y = view_projection.m7 + view_projection.m4;
planes[left].normal.z = view_projection.m11 + view_projection.m8;
planes[left].distance = view_projection.m15 + view_projection.m12;
/* Right Clipping Plane */
planes[right].normal.x = view_projection.m3 - view_projection.m0;
planes[right].normal.y = view_projection.m7 - view_projection.m4;
planes[right].normal.z = view_projection.m11 - view_projection.m8;
planes[right].distance = view_projection.m15 - view_projection.m12;
/* Bottom Clipping Plane */
planes[bottom].normal.x = view_projection.m3 + view_projection.m1;
planes[bottom].normal.y = view_projection.m7 + view_projection.m5;
planes[bottom].normal.z = view_projection.m11 + view_projection.m9;
planes[bottom].distance = view_projection.m15 + view_projection.m13;
/* Top Clipping Plane */
planes[top].normal.x = view_projection.m3 - view_projection.m1;
planes[top].normal.y = view_projection.m7 - view_projection.m5;
planes[top].normal.z = view_projection.m11 - view_projection.m9;
planes[top].distance = view_projection.m15 - view_projection.m13;
/* Near Clipping Plane */
planes[near].normal.x = view_projection.m3 + view_projection.m2;
planes[near].normal.y = view_projection.m7 + view_projection.m6;
planes[near].normal.z = view_projection.m11 + view_projection.m10;
planes[near].distance = view_projection.m15 + view_projection.m14;
/* Far Clipping Plane */
planes[far].normal.x = view_projection.m3 - view_projection.m2;
planes[far].normal.y = view_projection.m7 - view_projection.m6;
planes[far].normal.z = view_projection.m11 - view_projection.m10;
planes[far].distance = view_projection.m15 - view_projection.m14;
/* Normalize all planes so that normal length equals 1.0 */
for (uint8_t plane_index = 0; plane_index < number_of_planes; plane_index++)
{
float magnitude = sqrtf(
planes[plane_index].normal.x * planes[plane_index].normal.x +
planes[plane_index].normal.y * planes[plane_index].normal.y +
planes[plane_index].normal.z * planes[plane_index].normal.z
);
if (magnitude > 0.0f)
{
float inverse_magnitude = 1.0f / magnitude;
planes[plane_index].normal.x *= inverse_magnitude;
planes[plane_index].normal.y *= inverse_magnitude;
planes[plane_index].normal.z *= inverse_magnitude;
planes[plane_index].distance *= inverse_magnitude;
}
}
}
/**
* Checks if an Axis-Aligned Bounding Box (AABB) is within the view frustum.
* * This function performs a fast visibility test by finding the "positive vertex"
* of the box (the corner most aligned with the plane normal). If this vertex
* is outside any of the six planes, the entire box is considered culled.
*/
bool is_axis_aligned_bounding_box_in_frustum( const frustum_plane_struct planes
[
number_of_planes
],
BoundingBox bounds)
{
for (uint8_t plane_index = 0; plane_index < number_of_planes; plane_index++)
{
Vector3 positive_vertex;
positive_vertex.x =
(planes[plane_index].normal.x >= 0.0f) ? bounds.max.x : bounds.min.x;
positive_vertex.y =
(planes[plane_index].normal.y >= 0.0f) ? bounds.max.y : bounds.min.y;
positive_vertex.z =
(planes[plane_index].normal.z >= 0.0f) ? bounds.max.z : bounds.min.z;
/* Calculate the signed distance from the plane to the positive vertex */
float vertex_distance =
planes[plane_index].normal.x * positive_vertex.x +
planes[plane_index].normal.y * positive_vertex.y +
planes[plane_index].normal.z * positive_vertex.z +
planes[plane_index].distance;
/* If the most positive point is behind the plane, the box is outside the frustum */
if (vertex_distance < 0.0f)
{
return false;
}
}
return true;
}