billboard_rendering.c File Reference

#include "billboard_rendering.h"
#include "gl_common.h"
#include "instanced_rendering.h"
#include "render_utils.h"
#include <assert.h>
#include <stddef.h>

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Functions
void	billboard_group_init (BillboardGroup *group, const SphereInstance *data, int count)
	Initializes the billboard group and allocates GPU memory. More...
void	billboard_group_update (BillboardGroup *group, const SphereInstance *data, int count)
	Updates instance data on the GPU. More...
void	billboard_group_update_from_buffer (BillboardGroup *group, GLuint src_buffer, int count)
	Updates instance data on the GPU by copying from another GPU buffer (e.g. SSBO). More...
static void	setup_billboard_instance_attributes (void)
static void	create_billboard_vao (GLuint *vao, GLuint geometry_vbo, GLuint instance_vbo)
void	billboard_group_prepare (BillboardGroup *group, GLuint quad_vbo, GLuint wire_quad_vbo, GLuint wire_cube_vbo)
	Prepares the VAO by linking a shared quad VBO with internal instance data. More...
void	billboard_group_draw (BillboardGroup *group)
	Executes the instanced draw call for all billboards in the group. More...
void	billboard_group_cleanup (BillboardGroup *group)
	Releases all GPU resources allocated for the billboard group. More...
void	billboard_group_draw_debug_fill (BillboardGroup *group)
	Draws filled quads for each instance (for debug transparency). More...
void	billboard_group_draw_debug_quads (BillboardGroup *group)
	Draws wireframe quads for each instance. More...
void	billboard_group_draw_debug_boxes (BillboardGroup *group)
	Draws wireframe boxes for each instance. More...

Variables
static const int	WIRE_CUBE_VERTEX_COUNT = 24

Function Documentation

billboard_group_cleanup()

void billboard_group_cleanup

(

BillboardGroup *

group

)

Releases all GPU resources allocated for the billboard group.

Parameters

group

Pointer to the group.

billboard_group_draw()

void billboard_group_draw

(

BillboardGroup *

group

)

Executes the instanced draw call for all billboards in the group.

Parameters

group

Pointer to the group.

billboard_group_draw_debug_boxes()

void billboard_group_draw_debug_boxes

(

BillboardGroup *

group

)

Draws wireframe boxes for each instance.

Assumes the correct shader is already bound.

Parameters

group

Pointer to the group.

billboard_group_draw_debug_fill()

void billboard_group_draw_debug_fill

(

BillboardGroup *

group

)

Draws filled quads for each instance (for debug transparency).

Assumes the correct shader is already bound.

Parameters

group

Pointer to the group.

billboard_group_draw_debug_quads()

void billboard_group_draw_debug_quads

(

BillboardGroup *

group

)

Draws wireframe quads for each instance.

Assumes the correct shader is already bound.

Parameters

group

Pointer to the group.

billboard_group_init()

void billboard_group_init	(	BillboardGroup *	group,
		const SphereInstance *	data,
		int	count
	)

Initializes the billboard group and allocates GPU memory.

RESOURCE MANAGEMENT:

• This function creates OpenGL resources (VBO).
• MUST be paired with billboard_group_cleanup() to avoid memory leaks.
• Do NOT call init twice on the same group without cleanup in between.

Parameters

group	Pointer to the group (must be zero-initialized).
data	Initial instance data (can be NULL if only allocating).
count	Number of instances to allocate for.

billboard_group_prepare()

void billboard_group_prepare	(	BillboardGroup *	group,
		GLuint	quad_vbo,
		GLuint	wire_quad_vbo,
		GLuint	wire_cube_vbo
	)

Prepares the VAO by linking a shared quad VBO with internal instance data.

Parameters

group	Pointer to the group.
quad_vbo	VBO containing basic quad geometry (usually from render_utils).
wire_quad_vbo	VBO for debug wireframe quad.
wire_cube_vbo	VBO for debug wireframe unit box.

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billboard_group_update()

void billboard_group_update	(	BillboardGroup *	group,
		const SphereInstance *	data,
		int	count
	)

Updates instance data on the GPU.

Typically used for per-frame updates like sorting or movement.

Parameters

group	Pointer to the group.
data	New instance data.
count	Number of instances to update.

billboard_group_update_from_buffer()

void billboard_group_update_from_buffer	(	BillboardGroup *	group,
		GLuint	src_buffer,
		int	count
	)

Updates instance data on the GPU by copying from another GPU buffer (e.g. SSBO).

Use this when the sorted data is already on the GPU to avoid CPU roundtrips.

Parameters

group	Pointer to the group.
src_buffer	Handle of the source buffer.
count	Number of instances to update.

create_billboard_vao()

static void create_billboard_vao ( GLuint *  vao, GLuint  geometry_vbo, GLuint  instance_vbo  )

static

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setup_billboard_instance_attributes()

static void setup_billboard_instance_attributes ( void  )

static

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Variable Documentation

WIRE_CUBE_VERTEX_COUNT

const int WIRE_CUBE_VERTEX_COUNT = 24

static