billboard_sorting.h File Reference

Back-to-front sorting for transparent geometry. More...

#include "sphere_types.h"
#include <cglm/cglm.h>

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Data Structures
struct	BillboardSortEntry
	Lightweight proxy for sorting data without moving large structs. More...
struct	BillboardSorter
	Reusable memory context for sorting operations. More...

Functions
void	billboard_sorter_init (BillboardSorter *sorter, int initial_capacity)
	Allocates internal buffers for the sorter. More...
void	billboard_sorter_cleanup (BillboardSorter *sorter)
	Destroys the sorter context. More...
GLuint	billboard_sorter_sort_gpu (BillboardSorter *sorter, const SphereInstance *instances, int count, const vec3 camera_pos)
	Sorts the array of instances Back-to-Front (descending depth) on GPU. More...
GLuint	billboard_sorter_sort_cpu (BillboardSorter *sorter, const SphereInstance *instances, int count, const vec3 camera_pos)
	Sorts the array of instances Back-to-Front (descending depth) on CPU. More...
GLuint	billboard_sorter_sort_cpu_radix (BillboardSorter *sorter, const SphereInstance *instances, int count, const vec3 camera_pos)
	Sorts the array of instances Back-to-Front (descending depth) using Radix Sort. More...

Detailed Description

Back-to-front sorting for transparent geometry.

This module provides an efficient sorting mechanism for sphere instances, which is required for correct alpha blending of billboarded spheres.

Function Documentation

billboard_sorter_cleanup()

void billboard_sorter_cleanup

(

BillboardSorter *

sorter

)

Destroys the sorter context.

Parameters

sorter

Pointer to the struct.

billboard_sorter_init()

void billboard_sorter_init	(	BillboardSorter *	sorter,
		int	initial_capacity
	)

Allocates internal buffers for the sorter.

Parameters

sorter	Pointer to the struct.
initial_capacity	Expected number of instances.

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billboard_sorter_sort_cpu()

GLuint billboard_sorter_sort_cpu	(	BillboardSorter *	sorter,
		const SphereInstance *	instances,
		int	count,
		const vec3	camera_pos
	)

Sorts the array of instances Back-to-Front (descending depth) on CPU.

Uses qsort on the host and uploads the result to the SSBO.

Parameters

sorter	Memory context.
instances	Array of instances (will be copied and sorted internally).
count	Active element count.
camera_pos	World-space viewer position.

Returns

The SSBO handle containing the sorted instances.

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billboard_sorter_sort_cpu_radix()

GLuint billboard_sorter_sort_cpu_radix	(	BillboardSorter *	sorter,
		const SphereInstance *	instances,
		int	count,
		const vec3	camera_pos
	)

Sorts the array of instances Back-to-Front (descending depth) using Radix Sort.

Parameters

sorter	Memory context.
instances	Array of instances.
count	Active element count.
camera_pos	World-space viewer position (for depth).

Returns

The SSBO handle containing the sorted instances.

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billboard_sorter_sort_gpu()

GLuint billboard_sorter_sort_gpu	(	BillboardSorter *	sorter,
		const SphereInstance *	instances,
		int	count,
		const vec3	camera_pos
	)

Sorts the array of instances Back-to-Front (descending depth) on GPU.

Uploads instances to an SSBO, sorts them using a compute shader, and prepares them for rendering.

Parameters

sorter	Memory context.
instances	Pointer to the array of instances to upload.
count	Active element count.
camera_pos	World-space viewer position.

Returns

The SSBO handle containing the sorted instances.

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