ObjectBillboards Class

Billboards class is used to bake billboards with the same material into one object. (A texture atlas can be applied, if necessary.) This allows you to optimize application performance when rendering a big number of billboards: as the number of texture fetches is reduced and the spatial tree is less cluttered, rendering is sped up.

The following samples demonstrate the ObjectBillboards class usage:

• billboards_02
• billboards_03

ObjectBillboards Class

This class inherits from Object

Members

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ObjectBillboards ()

Constructor. Creates a new Billboards object.

int addBillboard (float width, float height)

Adds a new billboard to be managed by Billboards object.

Arguments

• float width - Width of the billboard in units.
• float height - Height of the billboard in units.

Return value

Added billboard number.

void allocateBillboards (int num)

Allocate a buffer for a given number of billboards to be created. With this function, memory can be allocated once rather than in chunks, making the creation faster.

Arguments

• int num - The number of billboards that will be stored in a buffer.

void clearBillboards ()

Deletes all billboards from Billboards object.

float getAngle (int num)

Returns the current orientation of a given billboard. Positive values mean clockwise rotated billboard, negative ones mean counter-clockwise rotation.

Arguments

• int num - Billboard number.

Return value

Angle in degrees.

int getDepthSort ()

Returns a value indicating whether depth sorting (in the back-to-front order) is enabled for billboards. This option should be enabled, if alpha blending is used for the billboard material (except for the additive blending).

Return value

1 if the depth sorting is enabled; otherwise, 0.

float getHeight (int num)

Returns the current height of a given billboard.

Arguments

• int num - Billboard number.

Return value

Height of the billboard in units.

int getNumBillboards ()

Returns the total number of billboards contained in and managed by Billboards object.

Return value

Number of billboards.

vec3 getPosition (int num)

Returns the position of the given billboard.

Arguments

• int num - Billboard number.

Return value

Billboard position coordinates.

vec4 getTexCoord (int num)

Returns the texture coordinates for for a given billboard (a texture atlas can be used).

• The first pair of coordinates (x and y) set texture scale by X and Y axes. For example, by the scale of 2 the texture is repeated twice on the billboard.
• The second pair (z and w) set texture offset along X and Y axes. For example, by the offset of 0.5 along X axis the texture is repositioned to the right (so that the edge of the texture is rendered in the center).

Arguments

• int num - Billboard number.

Return value

Texture coordinates.

float getWidth (int num)

Returns the current width of a given billboard.

Arguments

• int num - Billboard number.

Return value

Width of the billboard in units.

void removeBillboard (int num)

Deletes a given billboard from Billboards object.

Arguments

• int num - Billboard number.

void setAngle (int num, float angle)

Sets the orientation of a given billboard.

Arguments

• int num - Billboard number.
• float angle - Angle in degrees to set the billboard orientation. Positive values rotate the billboard clockwise, negative ones rotate it counter-clockwise.

void setDepthSort (int depth_sort)

Sets a value indicating if billboards should be sorted in the back-to-front order according to their position. This option should be enabled, if alpha blending is used for the billboard material (except for the additive blending).

Arguments

• int depth_sort - Positive number to enable depth sorting; 0 to disable.

void setHeight (int num, float width)

Sets the height of a given billboard.

Arguments

• int num - Billboard number.
• float width - Height of the billboard in units.

void setPosition (int num, vec3 position)

Sets the position for the given billboard.

Arguments

• int num - Billboard number.
• vec3 position - Billboard position coordinates.

void setTexCoord (int num, vec4 texcoord)

Sets texture coordinates for a given billboard (a texture atlas can be used).

• The first pair of coordinates (x and y) set texture scale by X and Y axes. For example, by the scale of 2 the texture is repeated twice on the billboard.
• The second pair (z and w) set texture offset along X and Y axes. For example, by the offset of 0.5 along X axis the texture is repositioned to the right (so that the edge of the texture is rendered in the center).

Arguments

• int num - Billboard number.
• vec4 texcoord - Texture coordinates.

void setWidth (int num, float width)

Sets the width of a given billboard.

Arguments

• int num - Billboard number.
• float width - Width of the billboard in units.