libdragon
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Hardware Display Interface

Interface to the hardware sprite/triangle rasterizer (RDP). More...

Files

file  rdp.c
 Hardware Display Interface.
 
file  rdp.h
 Hardware Display Interface.
 

Data Structures

struct  sprite_cache
 Cached sprite structure. More...
 

Macros

#define __get_buffer(x)   __safe_buffer[(x)-1]
 Grab the texture buffer given a display context. More...
 
#define RINGBUFFER_SIZE   4096
 Size of the internal ringbuffer that holds pending RDP commands.
 
#define RINGBUFFER_SLACK   1024
 Size of the slack are of the ring buffer. More...
 

Enumerations

enum  mirror_t { MIRROR_DISABLED , MIRROR_X , MIRROR_Y , MIRROR_XY }
 Mirror settings for textures. More...
 
enum  sync_t { SYNC_FULL , SYNC_PIPE , SYNC_LOAD , SYNC_TILE }
 RDP sync operations. More...
 
enum  flush_t { FLUSH_STRATEGY_NONE , FLUSH_STRATEGY_AUTOMATIC }
 Caching strategy for loaded textures. More...
 

Functions

void rdp_init (void)
 Initialize the RDP system.
 
void rdp_close (void)
 Close the RDP system. More...
 
void rdp_attach_display (display_context_t disp)
 Attach the RDP to a display context. More...
 
void rdp_detach_display (void)
 Detach the RDP from a display context. More...
 
void rdp_sync (sync_t sync)
 Perform a sync operation. More...
 
void rdp_set_clipping (uint32_t tx, uint32_t ty, uint32_t bx, uint32_t by)
 Set the hardware clipping boundary. More...
 
void rdp_set_default_clipping (void)
 Set the hardware clipping boundary to the entire screen.
 
void rdp_enable_primitive_fill (void)
 Enable display of 2D filled (untextured) rectangles. More...
 
void rdp_enable_blend_fill (void)
 Enable display of 2D filled (untextured) triangles. More...
 
void rdp_enable_texture_copy (void)
 Enable display of 2D sprites. More...
 
uint32_t rdp_load_texture (uint32_t texslot, uint32_t texloc, mirror_t mirror, sprite_t *sprite)
 Load a sprite into RDP TMEM. More...
 
uint32_t rdp_load_texture_stride (uint32_t texslot, uint32_t texloc, mirror_t mirror, sprite_t *sprite, int offset)
 Load part of a sprite into RDP TMEM. More...
 
void rdp_draw_textured_rectangle_scaled (uint32_t texslot, int tx, int ty, int bx, int by, double x_scale, double y_scale, mirror_t mirror)
 Draw a textured rectangle with a scaled texture. More...
 
void rdp_draw_textured_rectangle (uint32_t texslot, int tx, int ty, int bx, int by, mirror_t mirror)
 Draw a textured rectangle. More...
 
void rdp_draw_sprite (uint32_t texslot, int x, int y, mirror_t mirror)
 Draw a texture to the screen as a sprite. More...
 
void rdp_draw_sprite_scaled (uint32_t texslot, int x, int y, double x_scale, double y_scale, mirror_t mirror)
 Draw a texture to the screen as a scaled sprite. More...
 
void rdp_set_primitive_color (uint32_t color)
 Set the primitive draw color for subsequent filled primitive operations. More...
 
void rdp_set_blend_color (uint32_t color)
 Set the blend draw color for subsequent filled primitive operations. More...
 
void rdp_draw_filled_rectangle (int tx, int ty, int bx, int by)
 Draw a filled rectangle. More...
 
void rdp_draw_filled_triangle (float x1, float y1, float x2, float y2, float x3, float y3)
 Draw a filled triangle. More...
 
void rdp_set_texture_flush (flush_t flush)
 Set the flush strategy for texture loads. More...
 

Variables

uint32_t __bitdepth
 Currently active bit depth.
 
uint32_t __width
 Currently active video width (calculated)
 
uint32_t __height
 Currently active video height (calculated)
 
void * __safe_buffer []
 Pointer to uncached 16-bit aligned version of buffers.
 

Detailed Description

Interface to the hardware sprite/triangle rasterizer (RDP).

The hardware display interface sets up and talks with the RDP in order to render hardware sprites, triangles and rectangles. The RDP is a very low level rasterizer and needs data in a very specific format. The hardware display interface handles this by building commands to be sent to the RDP.

Before attempting to draw anything using the RDP, the hardware display interface should be initialized with rdp_init. After the RDP is no longer needed, be sure to free all resources using rdp_close.

Code wishing to use the hardware rasterizer should first acquire a display context using display_lock. Once a display context has been acquired, the RDP can be attached to the display context with rdp_attach_display. Once the display has been attached, the RDP can be used to draw sprites, rectangles and textured/untextured triangles to the display context. Note that some functions require additional setup, so read the descriptions for each function before use. After code has finished rendering hardware assisted graphics to the display context, the RDP can be detached from the context using rdp_detach_display. After calling thie function, it is safe to immediately display the rendered graphics to the screen using display_show, or additional software graphics manipulation can take place using functions from the 2D Graphics.

Careful use of the rdp_sync operation is required for proper rasterization. Before performing settings changes such as clipping changes or setting up texture or solid fill modes, code should perform a SYNC_PIPE. A SYNC_PIPE should be performed again before any new texture load. This is to ensure that the last texture operation is completed before attempting to change texture memory. Careful execution of texture operations can allow code to skip some sync operations. Be careful with excessive sync operations as it can stall the pipeline and cause triangles/rectangles to be drawn on the next display context instead of the current.

rdp_detach_display will automatically perform a SYNC_FULL to ensure that everything has been completed in the RDP. This call generates an interrupt when complete which signals the main thread that it is safe to detach. Consequently, interrupts must be enabled for proper operation. This also means that code should under normal circumstances never use SYNC_FULL.


Data Structure Documentation

◆ sprite_cache

struct sprite_cache

Cached sprite structure.

Data Fields
uint32_t s S location of the top left of the texture relative to the original texture.
uint32_t t T location of the top left of the texture relative to the original texture.
uint32_t width Width of the texture.
uint32_t height Height of the texture.
uint16_t real_width Width of the texture rounded up to next power of 2.
uint16_t real_height Height of the texture rounded up to next power of 2.

Macro Definition Documentation

◆ __get_buffer

#define __get_buffer (   x)    __safe_buffer[(x)-1]

Grab the texture buffer given a display context.

Parameters
[in]xThe display context returned from display_lock
Returns
A pointer to the drawing surface for that display context.

◆ RINGBUFFER_SLACK

#define RINGBUFFER_SLACK   1024

Size of the slack are of the ring buffer.

Data can be written into the slack area of the ring buffer by functions creating RDP commands. However, when sending a completed command to the RDP, if the buffer has advanced into the slack, it will be cleared and the pointer reset to start. This is to stop any commands from being split in the middle during wraparound.

Enumeration Type Documentation

◆ mirror_t

enum mirror_t

Mirror settings for textures.

Enumerator
MIRROR_DISABLED 

Disable texture mirroring.

MIRROR_X 

Enable texture mirroring on x axis.

MIRROR_Y 

Enable texture mirroring on y axis.

MIRROR_XY 

Enable texture mirroring on both x & y axis.

◆ sync_t

enum sync_t

RDP sync operations.

Enumerator
SYNC_FULL 

Wait for any operation to complete before causing a DP interrupt.

SYNC_PIPE 

Sync the RDP pipeline.

SYNC_LOAD 

Block until all texture load operations are complete.

SYNC_TILE 

Block until all tile operations are complete.

◆ flush_t

enum flush_t

Caching strategy for loaded textures.

Enumerator
FLUSH_STRATEGY_NONE 

Textures are assumed to be pre-flushed.

FLUSH_STRATEGY_AUTOMATIC 

Cache will be flushed on all incoming textures.

Function Documentation

◆ rdp_close()

void rdp_close ( void  )

Close the RDP system.

This function closes out the RDP system and cleans up any internal memory allocated by rdp_init.

◆ rdp_attach_display()

void rdp_attach_display ( display_context_t  disp)

Attach the RDP to a display context.

This function allows the RDP to operate on display contexts fetched with display_lock. This should be performed before any other operations to ensure that the RDP has a valid output buffer to operate on.

Parameters
[in]dispA display context as returned by display_lock

◆ rdp_detach_display()

void rdp_detach_display ( void  )

Detach the RDP from a display context.

Note
This function requires interrupts to be enabled to operate properly.

This function will ensure that all hardware operations have completed on an output buffer before detaching the display context. This should be performed before displaying the finished output using display_show

◆ rdp_sync()

void rdp_sync ( sync_t  sync)

Perform a sync operation.

Do not use excessive sync operations between commands as this can cause the RDP to stall. If the RDP stalls due to too many sync operations, graphics may not be displayed until the next render cycle, causing bizarre artifacts. The rule of thumb is to only add a sync operation if the data you need is not yet available in the pipeline.

Parameters
[in]syncThe sync operation to perform on the RDP

◆ rdp_set_clipping()

void rdp_set_clipping ( uint32_t  tx,
uint32_t  ty,
uint32_t  bx,
uint32_t  by 
)

Set the hardware clipping boundary.

Parameters
[in]txTop left X coordinate in pixels
[in]tyTop left Y coordinate in pixels
[in]bxBottom right X coordinate in pixels
[in]byBottom right Y coordinate in pixels

◆ rdp_enable_primitive_fill()

void rdp_enable_primitive_fill ( void  )

Enable display of 2D filled (untextured) rectangles.

This must be called before using rdp_draw_filled_rectangle.

◆ rdp_enable_blend_fill()

void rdp_enable_blend_fill ( void  )

Enable display of 2D filled (untextured) triangles.

This must be called before using rdp_draw_filled_triangle.

◆ rdp_enable_texture_copy()

void rdp_enable_texture_copy ( void  )

Enable display of 2D sprites.

This must be called before using rdp_draw_textured_rectangle_scaled, rdp_draw_textured_rectangle, rdp_draw_sprite or rdp_draw_sprite_scaled.

◆ rdp_load_texture()

uint32_t rdp_load_texture ( uint32_t  texslot,
uint32_t  texloc,
mirror_t  mirror,
sprite_t sprite 
)

Load a sprite into RDP TMEM.

Parameters
[in]texslotThe RDP texture slot to load this sprite into (0-7)
[in]texlocThe RDP TMEM offset to place the texture at
[in]mirrorWhether the sprite should be mirrored when displaying past boundaries
[in]spritePointer to sprite structure to load the texture from
Returns
The number of bytes consumed in RDP TMEM by loading this sprite

◆ rdp_load_texture_stride()

uint32_t rdp_load_texture_stride ( uint32_t  texslot,
uint32_t  texloc,
mirror_t  mirror,
sprite_t sprite,
int  offset 
)

Load part of a sprite into RDP TMEM.

Given a sprite with vertical and horizontal slices defined, this function will load the slice specified in offset into texture memory. This is usefl for treating a large sprite as a tilemap.

Given a sprite with 3 horizontal slices and two vertical slices, the offsets are as follows:

*---*---*---*
| 0 | 1 | 2 |
*---*---*---*
| 3 | 4 | 5 |
*---*---*---*
Parameters
[in]texslotThe RDP texture slot to load this sprite into (0-7)
[in]texlocThe RDP TMEM offset to place the texture at
[in]mirrorWhether the sprite should be mirrored when displaying past boundaries
[in]spritePointer to sprite structure to load the texture from
[in]offsetOffset of the particular slice to load into RDP TMEM.
Returns
The number of bytes consumed in RDP TMEM by loading this sprite

◆ rdp_draw_textured_rectangle_scaled()

void rdp_draw_textured_rectangle_scaled ( uint32_t  texslot,
int  tx,
int  ty,
int  bx,
int  by,
double  x_scale,
double  y_scale,
mirror_t  mirror 
)

Draw a textured rectangle with a scaled texture.

Given an already loaded texture, this function will draw a rectangle textured with the loaded texture at a scale other than 1. This allows rectangles to be drawn with stretched or squashed textures. If the rectangle is larger than the texture after scaling, it will be tiled or mirrored based on the mirror setting given in the load texture command.

Before using this command to draw a textured rectangle, use rdp_enable_texture_copy to set the RDP up in texture mode.

Parameters
[in]texslotThe texture slot that the texture was previously loaded into (0-7)
[in]txThe pixel X location of the top left of the rectangle
[in]tyThe pixel Y location of the top left of the rectangle
[in]bxThe pixel X location of the bottom right of the rectangle
[in]byThe pixel Y location of the bottom right of the rectangle
[in]x_scaleHorizontal scaling factor
[in]y_scaleVertical scaling factor
[in]mirrorWhether the texture should be mirrored

◆ rdp_draw_textured_rectangle()

void rdp_draw_textured_rectangle ( uint32_t  texslot,
int  tx,
int  ty,
int  bx,
int  by,
mirror_t  mirror 
)

Draw a textured rectangle.

Given an already loaded texture, this function will draw a rectangle textured with the loaded texture. If the rectangle is larger than the texture, it will be tiled or mirrored based on the* mirror setting given in the load texture command.

Before using this command to draw a textured rectangle, use rdp_enable_texture_copy to set the RDP up in texture mode.

Parameters
[in]texslotThe texture slot that the texture was previously loaded into (0-7)
[in]txThe pixel X location of the top left of the rectangle
[in]tyThe pixel Y location of the top left of the rectangle
[in]bxThe pixel X location of the bottom right of the rectangle
[in]byThe pixel Y location of the bottom right of the rectangle
[in]mirrorWhether the texture should be mirrored

◆ rdp_draw_sprite()

void rdp_draw_sprite ( uint32_t  texslot,
int  x,
int  y,
mirror_t  mirror 
)

Draw a texture to the screen as a sprite.

Given an already loaded texture, this function will draw a rectangle textured with the loaded texture.

Before using this command to draw a textured rectangle, use rdp_enable_texture_copy to set the RDP up in texture mode.

Parameters
[in]texslotThe texture slot that the texture was previously loaded into (0-7)
[in]xThe pixel X location of the top left of the sprite
[in]yThe pixel Y location of the top left of the sprite
[in]mirrorWhether the texture should be mirrored

◆ rdp_draw_sprite_scaled()

void rdp_draw_sprite_scaled ( uint32_t  texslot,
int  x,
int  y,
double  x_scale,
double  y_scale,
mirror_t  mirror 
)

Draw a texture to the screen as a scaled sprite.

Given an already loaded texture, this function will draw a rectangle textured with the loaded texture.

Before using this command to draw a textured rectangle, use rdp_enable_texture_copy to set the RDP up in texture mode.

Parameters
[in]texslotThe texture slot that the texture was previously loaded into (0-7)
[in]xThe pixel X location of the top left of the sprite
[in]yThe pixel Y location of the top left of the sprite
[in]x_scaleHorizontal scaling factor
[in]y_scaleVertical scaling factor
[in]mirrorWhether the texture should be mirrored

◆ rdp_set_primitive_color()

void rdp_set_primitive_color ( uint32_t  color)

Set the primitive draw color for subsequent filled primitive operations.

This function sets the color of all rdp_draw_filled_rectangle operations that follow. Note that in 16 bpp mode, the color must be a packed color. This means that the high 16 bits and the low 16 bits must both be the same color. Use graphics_make_color or graphics_convert_color to generate valid colors.

Parameters
[in]colorColor to draw primitives in

◆ rdp_set_blend_color()

void rdp_set_blend_color ( uint32_t  color)

Set the blend draw color for subsequent filled primitive operations.

This function sets the color of all rdp_draw_filled_triangle operations that follow.

Parameters
[in]colorColor to draw primitives in

◆ rdp_draw_filled_rectangle()

void rdp_draw_filled_rectangle ( int  tx,
int  ty,
int  bx,
int  by 
)

Draw a filled rectangle.

Given a color set with rdp_set_primitive_color, this will draw a filled rectangle to the screen. This is most often useful for erasing a buffer before drawing to it by displaying a black rectangle the size of the screen. This is much faster than setting the buffer blank in software. However, if you are planning on drawing to the entire screen, blanking may be unnecessary.

Before calling this function, make sure that the RDP is set to primitive mode by calling rdp_enable_primitive_fill.

Parameters
[in]txPixel X location of the top left of the rectangle
[in]tyPixel Y location of the top left of the rectangle
[in]bxPixel X location of the bottom right of the rectangle
[in]byPixel Y location of the bottom right of the rectangle

◆ rdp_draw_filled_triangle()

void rdp_draw_filled_triangle ( float  x1,
float  y1,
float  x2,
float  y2,
float  x3,
float  y3 
)

Draw a filled triangle.

Given a color set with rdp_set_blend_color, this will draw a filled triangle to the screen. Vertex order is not important.

Before calling this function, make sure that the RDP is set to blend mode by calling rdp_enable_blend_fill.

Parameters
[in]x1Pixel X1 location of triangle
[in]y1Pixel Y1 location of triangle
[in]x2Pixel X2 location of triangle
[in]y2Pixel Y2 location of triangle
[in]x3Pixel X3 location of triangle
[in]y3Pixel Y3 location of triangle

◆ rdp_set_texture_flush()

void rdp_set_texture_flush ( flush_t  flush)

Set the flush strategy for texture loads.

If textures are guaranteed to be in uncached RDRAM or the cache is flushed before calling load operations, the RDP can be told to skip flushing the cache. This affords a good speedup. However, if you are changing textures in memory on the fly or otherwise do not want to deal with cache coherency, set the cache strategy to automatic to have the RDP flush cache before texture loads.

Parameters
[in]flushThe cache strategy, either FLUSH_STRATEGY_NONE or FLUSH_STRATEGY_AUTOMATIC.