# GeoMipTerrain¶

class GeoMipTerrain

Bases: TypedObject

GeoMipTerrain, meaning Panda3D GeoMipMapping, can convert a heightfield image into a 3D terrain, consisting of several GeomNodes. It uses the GeoMipMapping algorithm, or Geometrical MipMapping, based on the LOD (Level of Detail) algorithm. For more information about the GeoMipMapping algoritm, see this paper, written by Willem H. de Boer: https://flipcode.com/articles/article_geomipmaps.pdf

Inheritance diagram

enum AutoFlattenMode

The flatten mode specifies whether the terrain nodes are flattened together after each terrain update.

enumerator AFM_off = 0

FM_off: don’t ever flatten the terrain.

enumerator AFM_light = 1

FM_light: the terrain is flattened using flatten_light.

enumerator AFM_medium = 2

FM_medium: the terrain is flattened using flatten_medium.

enumerator AFM_strong = 3

FM_strong: the terrain is flattened using flatten_strong.

explicit GeoMipTerrain(std::string const &name)
void calc_ambient_occlusion(PN_stdfloat radius = 32, PN_stdfloat contrast = 2.0, PN_stdfloat brightness = 0.7500000000000001)

Calculates an approximate for the ambient occlusion and stores it in the color map, so that it will be written to the vertex colors. Any existing color map will be discarded. You need to call this before generating the geometry.

void clear_color_map(void)

Clears the color map.

PNMImage &color_map(void)

Returns a reference to the color map (a PNMImage) contained inside GeoMipTerrain. You can use the reference to alter the color map.

void generate(void)

(Re)generates the entire terrain, erasing the current. This call un- flattens the terrain, so make sure you have set auto-flatten if you want to keep your terrain flattened.

LVecBase2 get_block_from_pos(double x, double y)

Gets the coordinates of the block at the specified position. This position must be relative to the terrain, not to render. Returns an array containing two values: the block x and the block y coords. If the positions are out of range, the closest block is taken. Note that the VecBase returned does not represent a vector, position, or rotation, but it contains the block index of the block which you can use in GeoMipTerrain::get_block_node_path().

NodePath const get_block_node_path(unsigned short int mx, unsigned short int my)

Returns the NodePath of the specified block. If auto-flatten is enabled and the node is getting removed during the flattening process, it will still return a NodePath with the appropriate terrain chunk, but it will be in a temporary scenegraph. Please note that this returns a const object and you can not modify the node. Modify the heightfield instead.

unsigned short int get_block_size(void)

Gets the block size.

bool get_border_stitching(void)

Returns the current stitching setting. False by default, unless set_stitching has been set.

bool get_bruteforce(void)

Returns a boolean whether the terrain is rendered bruteforce or not. See set_bruteforce() for more information.

static TypeHandle get_class_type(void)
double get_elevation(double x, double y)

Fetches the elevation at (x, y), where the input coordinate is specified in pixels. This ignores the current LOD level and instead provides an accurate number. Linear blending is used for non-integral coordinates. Terrain scale is NOT taken into account! To get accurate normals, please multiply this with the terrain Z scale!

trueElev = terr.get_elevation(x,y) * terr.get_sz();

double get_far(void)

Returns the far LOD distance in the terrain coordinate space

int get_flatten_mode(void)

Returns the automatic-flatten mode (e.g., off, flatten_light, flatten_medium, or flatten_strong)

NodePath get_focal_point(void) const

Returns the focal point, as a NodePath. If you have set it to be just a point, it will return an empty node at the focal position.

unsigned short int get_max_level(void)

Returns the highest level possible for this block size. When a block is at this level, it will be the worst quality possible.

unsigned short int get_min_level(void)

Gets the minimum level of detail at which blocks may be generated by generate() or update(). The default value is 0, which is the highest quality.

double get_near(void)

Returns the near LOD distance in the terrain coordinate space

LVector3 get_normal(int x, int y)
LVector3 get_normal(unsigned short int mx, unsigned short int my, int x, int y)

Fetches the terrain normal at (x,y), where the input coordinate is specified in pixels. This ignores the current LOD level and instead provides an accurate number. Terrain scale is NOT taken into account! To get accurate normals, please divide it by the terrain scale and normalize it again!

Fetches the terrain normal at (x, y), where the input coordinate is specified in pixels. This ignores the current LOD level and instead provides an accurate number. Terrain scale is NOT taken into account! To get accurate normals, please divide it by the terrain scale and normalize it again, like this:

LVector3 normal (terr.get_normal(x, y)); normal.set(normal.get_x() / root.get_sx(), normal.get_y() / root.get_sy(), normal.get_z() / root.get_sz()); normal.normalize();

NodePath get_root(void) const

Returns the root of the terrain. This is a single PandaNode to which all the rest of the terrain is parented. The generate and update operations replace the nodes which are parented to this root, but they don’t replace this root itself.

bool has_color_map(void) const

Returns whether a color map has been set.

PNMImage &heightfield(void)

Returns a reference to the heightfield (a PNMImage) contained inside GeoMipTerrain. You can use the reference to alter the heightfield.

bool is_dirty(void)

Returns a bool indicating whether the terrain is marked ‘dirty’, that means the terrain has to be regenerated on the next update() call, because for instance the heightfield has changed. Once the terrain has been regenerated, the dirty flag automatically gets reset internally.

PNMImage make_slope_image(void)

Returns a new grayscale image containing the slope angles. A white pixel value means a vertical slope, while a black pixel will mean that the terrain is entirely flat at that pixel. You can translate it to degrees by mapping the greyscale values from 0 to 90 degrees. The resulting image will have the same size as the heightfield image. The scale will be taken into respect – meaning, if you change the terrain scale, the slope image will need to be regenerated in order to be correct.

void set_auto_flatten(int mode)

The terrain can be automatically flattened (using flatten_light, flatten_medium, or flatten_strong) after each update. This only affects future updates, it doesn’t flatten the current terrain.

void set_block_size(unsigned short int newbs)

Sets the block size. If it is not a power of two, the closest power of two is used.

void set_border_stitching(bool stitching)

If this value is true, the LOD level at the borders of the terrain will be 0. This is useful if you have multiple terrains attached and you want to stitch them together, to fix seams. This setting also has effect when bruteforce is enabled, although in that case you are probably better off with setting the minlevels to the same value.

void set_bruteforce(bool bf)

Sets a boolean specifying whether the terrain will be rendered bruteforce. If the terrain is rendered bruteforce, there will be no Level of Detail, and the update() call will only update the terrain if it is marked dirty.

bool set_color_map(Filename const &filename, PNMFileType *type = nullptr)
bool set_color_map(PNMImage const &image)
bool set_color_map(Texture const *image)
bool set_color_map(std::string const &path)

Loads the specified image as color map. The next time generate() is called, the terrain is painted with this color map using the vertex color column. Returns a boolean indicating whether the operation has succeeded.

void set_factor(PN_stdfloat factor)

DEPRECATED method. Use set_near/far instead. Sets the quality factor at which blocks must be generated. The higher this level, the better quality the terrain will be, but more expensive to render. A value of 0 makes the terrain the lowest quality possible, depending on blocksize. The default value is 100.

void set_far(double input_far)

Sets the far LOD distance, at which the terrain will be rendered at lowest quality. This distance is in the terrain’s coordinate space!

void set_focal_point(LPoint2d const &fp)
void set_focal_point(LPoint2f const &fp)
void set_focal_point(LPoint3d const &fp)
void set_focal_point(LPoint3f const &fp)
void set_focal_point(double x, double y)
void set_focal_point(NodePath fnp)

The focal point is the point at which the terrain will have the highest quality (lowest level of detail). Parts farther away from the focal point will have a lower quality (higher level of detail). The focal point is not taken in respect if bruteforce is set true.

Sets the focal point. GeoMipTerrain generates high-resolution terrain around the focal point, and progressively lower and lower resolution terrain as you get farther away. If a point is supplied and not a NodePath, make sure it’s relative to the terrain. Only the x and y coordinates of the focal point are taken in respect.

bool set_heightfield(Filename const &filename, PNMFileType *type = nullptr)
bool set_heightfield(PNMImage const &image)

Loads the specified heightmap image file into the heightfield. Returns true if succeeded, or false if an error has occured. If the heightmap is not a power of two plus one, it is scaled up using a gaussian filter.

void set_min_level(unsigned short int minlevel)

Sets the minimum level of detail at which blocks may be generated by generate() or update(). The default value is 0, which is the highest quality. This value is also taken in respect when generating the terrain bruteforce.

void set_near(double input_near)

Sets the near LOD distance, at which the terrain will be rendered at highest quality. This distance is in the terrain’s coordinate space!

void set_near_far(double input_near, double input_far)

Sets the near and far LOD distances in one call.

bool update(void)

Loops through all of the terrain blocks, and checks whether they need to be updated. If that is indeed the case, it regenerates the mipmap. Returns a true when the terrain has changed. Returns false when the terrain isn’t updated at all. If there is no terrain yet, it generates the entire terrain. This call un-flattens the terrain, so make sure you have set auto-flatten if you want to keep your terrain flattened.