/usr/include/libplacebo/gpu.h is in libplacebo-dev 0.4.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 | /*
* This file is part of libplacebo.
*
* libplacebo is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* libplacebo is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with libplacebo. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef LIBPLACEBO_GPU_H_
#define LIBPLACEBO_GPU_H_
#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include <libplacebo/common.h>
// This file contains the definition of an API which is designed to abstract
// away from platform-specific APIs like the various OpenGL variants, Direct3D
// and Vulkan in a common way. It is a much more limited API than those APIs,
// since it tries targetting a very small common subset of features that is
// needed to implement libplacebo's rendering.
//
// NOTE: When speaking of "valid usage" or "must", invalid usage is assumed to
// result in undefined behavior. (Typically, an error message is printed to
// stderr and libplacebo aborts). So ensuring valid API usage by the API user is
// absolutely crucial. If you want to be freed from this reponsibility, use the
// higher level abstractions provided by libplacebo alongside gpu.h.
// Structure which wraps metadata describing GLSL capabilities.
struct pl_glsl_desc {
int version; // GLSL version (e.g. 450), for #version
bool gles; // GLSL ES semantics (ESSL)
bool vulkan; // GL_KHR_vulkan_glsl semantics
};
typedef uint64_t pl_gpu_caps;
enum {
PL_GPU_CAP_COMPUTE = 1 << 0, // supports compute shaders
PL_GPU_CAP_PARALLEL_COMPUTE = 1 << 1, // supports multiple compute queues
PL_GPU_CAP_INPUT_VARIABLES = 1 << 2, // supports shader input variables
};
// Structure defining the physical limits of this GPU instance. If a limit is
// given as 0, that means that feature is unsupported.
struct pl_gpu_limits {
int max_tex_1d_dim; // maximum width for a 1D texture
int max_tex_2d_dim; // maximum width/height for a 2D texture (required)
int max_tex_3d_dim; // maximum width/height/depth for a 3D texture
size_t max_pushc_size; // maximum push_constants_size
size_t max_xfer_size; // maximum size of a PL_BUF_TEX_TRANSFER
size_t max_ubo_size; // maximum size of a PL_BUF_UNIFORM
size_t max_ssbo_size; // maximum size of a PL_BUF_STORAGE
int max_buffer_texels; // maximum texels in a PL_BUF_TEXEL_*
int min_gather_offset; // minimum textureGatherOffset offset
int max_gather_offset; // maximum textureGatherOffset offset
// Compute shader limits. Always available (non-zero) if PL_GPU_CAP_COMPUTE set
size_t max_shmem_size; // maximum compute shader shared memory size
int max_group_threads; // maximum number of local threads per work group
int max_group_size[3]; // maximum work group size per dimension
int max_dispatch[3]; // maximum dispatch size per dimension
// These don't represent hard limits but indicate performance hints for
// optimal alignment. For best performance, the corresponding field
// should be aligned to a multiple of these. They will always be a power
// of two.
int align_tex_xfer_stride; // optimal pl_tex_transfer_params.stride_w/h
size_t align_tex_xfer_offset; // optimal pl_tex_transfer_params.buf_offset
};
// Abstract device context which wraps an underlying graphics context and can
// be used to dispatch rendering commands.
struct pl_gpu {
struct pl_context *ctx; // the pl_context this GPU was initialized from
struct pl_gpu_fns *impl; // the underlying implementation (unique per GPU)
void *priv;
pl_gpu_caps caps; // PL_GPU_CAP_* bit field
struct pl_glsl_desc glsl; // GLSL version supported by this GPU
struct pl_gpu_limits limits; // physical device limits
// Note: Every GPU must support at least one of PL_GPU_CAP_INPUT_VARIABLES
// or uniform buffers (limits.max_ubo_size > 0).
// Supported texture formats, in preference order. (If there are multiple
// similar formats, the "better" ones come first)
const struct pl_fmt **formats;
int num_formats;
};
// Helper function to align the given dimension (e.g. width or height) to a
// multiple of the optimal texture transfer stride.
int pl_optimal_transfer_stride(const struct pl_gpu *gpu, int dimension);
enum pl_fmt_type {
PL_FMT_UNKNOWN = 0, // also used for inconsistent multi-component formats
PL_FMT_UNORM, // unsigned, normalized integer format (sampled as float)
PL_FMT_SNORM, // signed, normalized integer format (sampled as float)
PL_FMT_UINT, // unsigned integer format (sampled as integer)
PL_FMT_SINT, // signed integer format (sampled as integer)
PL_FMT_FLOAT, // (signed) float formats, any bit size
PL_FMT_TYPE_COUNT,
};
enum pl_fmt_caps {
PL_FMT_CAP_SAMPLEABLE = 1 << 0, // may be sampled from (PL_DESC_SAMPLED_TEX)
PL_FMT_CAP_STORABLE = 1 << 1, // may be used as storage image (PL_DESC_STORAGE_IMG)
PL_FMT_CAP_LINEAR = 1 << 2, // may be linearly samplied from (PL_TEX_SAMPLE_LINEAR)
PL_FMT_CAP_RENDERABLE = 1 << 3, // may be rendered to (pl_pass_params.target_fmt)
PL_FMT_CAP_BLENDABLE = 1 << 4, // may be blended to (pl_pass_params.enable_blend)
PL_FMT_CAP_BLITTABLE = 1 << 5, // may be blitted from/to (pl_tex_blit)
PL_FMT_CAP_VERTEX = 1 << 6, // may be used as a vertex attribute
PL_FMT_CAP_TEXEL_UNIFORM = 1 << 7, // may be used as a texel uniform buffer
PL_FMT_CAP_TEXEL_STORAGE = 1 << 8, // may be used as a texel storage buffer
// Notes:
// - PL_FMT_CAP_LINEAR also implies PL_FMT_CAP_SAMPLEABLE
// - PL_FMT_CAP_STORABLE also implies PL_GPU_CAP_COMPUTE
// - PL_FMT_CAP_VERTEX implies that the format is non-opaque
};
// Structure describing a texel/vertex format.
struct pl_fmt {
const char *name; // symbolic name for this format (e.g. rgba32f)
const void *priv;
enum pl_fmt_type type; // the format's data type and interpretation
enum pl_fmt_caps caps; // the features supported by this format
int num_components; // number of components for this format
int component_depth[4]; // meaningful bits per component, texture precision
// This controls the relationship between the data as seen by the host and
// the way it's interpreted by the texture. The host representation is
// always tightly packed (no padding bits in between each component).
//
// If `opaque` is true, then there's no meaningful correspondence between
// the two, and all of the remaining fields in this section are unset.
//
// If `emulated` is true, then this format doesn't actually exist on the
// GPU as an uploadable texture format - and any apparent support is being
// emulated (typically using compute shaders in the upload path).
bool opaque;
bool emulated;
size_t texel_size; // total size in bytes per texel
int host_bits[4]; // number of meaningful bits in host memory
int sample_order[4]; // sampled index for each component, e.g.
// {2, 1, 0, 3} for BGRA textures
// If usable as a vertex or texel buffer format, this gives the GLSL type
// corresponding to the data. (e.g. vec4)
const char *glsl_type;
// If usable as a storage image or texel storage buffer
// (PL_FMT_CAP_STORABLE / PL_FMT_CAP_TEXEL_STORAGE), this gives the GLSL
// texel format corresponding to the format. (e.g. rgba16ui)
const char *glsl_format;
};
// Returns whether or not a pl_fmt's components are ordered sequentially
// in memory in the order RGBA.
bool pl_fmt_is_ordered(const struct pl_fmt *fmt);
// Helper function to find a format with a given number of components and
// minimum effective precision per component. If `host_bits` is set, then the
// format will always be non-opaque, unpadded, ordered and have exactly this
// bit depth for each component. Finally, all `caps` must be supported.
const struct pl_fmt *pl_find_fmt(const struct pl_gpu *gpu, enum pl_fmt_type type,
int num_components, int min_depth,
int host_bits, enum pl_fmt_caps caps);
// Finds a vertex format for a given configuration. The resulting vertex will
// have a component depth equivalent to to the sizeof() the equivalent host type.
// (e.g. PL_FMT_FLOAT will always have sizeof(float))
const struct pl_fmt *pl_find_vertex_fmt(const struct pl_gpu *gpu,
enum pl_fmt_type type,
int num_components);
// Find a format based on its name.
const struct pl_fmt *pl_find_named_fmt(const struct pl_gpu *gpu, const char *name);
enum pl_tex_sample_mode {
PL_TEX_SAMPLE_NEAREST, // nearest neighour sampling
PL_TEX_SAMPLE_LINEAR, // linear filtering
};
enum pl_tex_address_mode {
PL_TEX_ADDRESS_CLAMP, // clamp the nearest edge texel
PL_TEX_ADDRESS_REPEAT, // repeat (tile) the texture
PL_TEX_ADDRESS_MIRROR, // repeat (mirror) the texture
};
// Structure describing a texture.
struct pl_tex_params {
int w, h, d; // physical dimension; unused dimensions must be 0
const struct pl_fmt *format;
// The following bools describe what operations can be performed. The
// corresponding pl_fmt capability must be set for every enabled
// operation type.
bool sampleable; // usable as a PL_DESC_SAMPLED_TEX
bool renderable; // usable as a render target (pl_pass_run)
// (must only be used with 2D textures)
bool storable; // usable as a storage image (PL_DESC_IMG_*)
bool blit_src; // usable as a blit source
bool blit_dst; // usable as a blit destination
bool host_writable; // may be updated with pl_tex_upload()
bool host_readable; // may be fetched with pl_tex_download()
// The following capabilities are only relevant for textures which have
// either sampleable or blit_src enabled.
enum pl_tex_sample_mode sample_mode;
enum pl_tex_address_mode address_mode;
// If non-NULL, the texture will be created with these contents. Using
// this does *not* require setting host_writable. Otherwise, the initial
// data is undefined.
const void *initial_data;
};
static inline int pl_tex_params_dimension(const struct pl_tex_params params)
{
return params.d ? 3 : params.h ? 2 : 1;
}
// Conflates the following typical GPU API concepts:
// - texture itself
// - sampler state
// - staging buffers for texture upload
// - framebuffer objects
// - wrappers for swapchain framebuffers
// - synchronization needed for upload/rendering/etc.
//
// Essentially a pl_tex can be anything ranging from a normal texture, a wrapped
// external/real framebuffer, a framebuffer object + texture pair, a mapped
// texture (via pl_hwdec), or other sorts of things that can be sampled from
// and/or rendered to.
struct pl_tex {
struct pl_tex_params params;
void *priv;
};
// Create a texture (with undefined contents). Returns NULL on failure. This is
// assumed to be an expensive/rare operation, and may need to perform memory
// allocation or framebuffer creation.
const struct pl_tex *pl_tex_create(const struct pl_gpu *gpu,
const struct pl_tex_params *params);
void pl_tex_destroy(const struct pl_gpu *gpu, const struct pl_tex **tex);
// Invalidates the contents of a texture. After this, the contents are fully
// undefined.
void pl_tex_invalidate(const struct pl_gpu *gpu, const struct pl_tex *tex);
// Clear the dst texture with the given color (rgba). This is functionally
// identical to a blit operation, which means dst->params.blit_dst must be
// set.
void pl_tex_clear(const struct pl_gpu *gpu, const struct pl_tex *dst,
const float color[4]);
// Copy a sub-rectangle from one texture to another. The source/dest regions
// must be within the texture bounds. Areas outside the dest region are
// preserved. The formats of the textures must be loosely compatible - which
// essentially means that they must have the same texel size. Additionally,
// UINT textures can only be blitted to other UINT textures, and SINT textures
// can only be blitted to other SINT textures. Finally, src.blit_src and
// dst.blit_dst must be set, respectively.
//
// The rectangles may be "flipped", which leads to the image being flipped
// while blitting. If the src and dst rects have different sizes, the source
// image will be scaled according to src->params.sample_mode. That said, the
// src and dst rects must be fully contained within the src/dst dimensions.
void pl_tex_blit(const struct pl_gpu *gpu,
const struct pl_tex *dst, const struct pl_tex *src,
struct pl_rect3d dst_rc, struct pl_rect3d src_rc);
// Structure describing a texture transfer operation.
struct pl_tex_transfer_params {
// Texture to transfer to/from. Depending on the type of the operation,
// this must have params.host_writable (uploads) or params.host_readable
// (downloads) set, respectively.
const struct pl_tex *tex;
// Note: Superfluous parameters are ignored, i.e. for a 1D texture, the y
// and z fields of `rc`, as well as the corresponding strides, are ignored.
// In all other cases, the stride must be >= the corresponding dimension
// of `rc`, and the `rc` must be normalized and fully contained within the
// image dimensions. If any of these parameters are left away (0), they
// are inferred from the texture's size.
struct pl_rect3d rc; // region of the texture to transfer
unsigned int stride_w; // the number of texels per horizontal row (x axis)
unsigned int stride_h; // the number of texels per vertical column (y axis)
// For the data source/target of a transfer operation, there are two valid
// options:
//
// 1. Transferring to/from a buffer:
const struct pl_buf *buf; // buffer to use (type must be PL_BUF_TEX_TRANSFER)
size_t buf_offset; // offset of data within buffer, must be a multiple of 4
// 2. Transferring to/from host memory directly:
void *ptr; // address of data
// The contents of the memory region / buffer must exactly match the
// texture format; i.e. there is no explicit conversion between formats.
// For data uploads, which are typically "fire and forget" operations,
// which method used does not matter much; although uploading from a host
// mapped buffer requires fewer memory copy operations and is therefore
// advised when uploading large amounts of data frequently.
// For data downloads, downloading directly to host memory is a blocking
// operation and should therefore be avoided as much as possible. It's
// highyly recommended to always use a texture transfer buffer for texture
// downloads if possible, which allows the transfer to happen
// asynchronously.
// When performing a texture transfer using a buffer, the buffer may be
// marked as "in use" and should not used for a different type of operation
// until pl_buf_poll returns false.
};
// Upload data to a texture. Returns whether successful.
bool pl_tex_upload(const struct pl_gpu *gpu,
const struct pl_tex_transfer_params *params);
// Download data from a texture. Returns whether successful.
bool pl_tex_download(const struct pl_gpu *gpu,
const struct pl_tex_transfer_params *params);
// Buffer usage type. This restricts what types of operations may be performed
// on a buffer.
enum pl_buf_type {
PL_BUF_INVALID = 0,
PL_BUF_TEX_TRANSFER, // texture transfer buffer (for pl_tex_upload/download)
PL_BUF_UNIFORM, // UBO, for PL_DESC_BUF_UNIFORM
PL_BUF_STORAGE, // SSBO, for PL_DESC_BUF_STORAGE
PL_BUF_TEXEL_UNIFORM,// texel buffer, for PL_DESC_BUF_TEXEL_UNIFORM
PL_BUF_TEXEL_STORAGE,// texel buffer, for PL_DESC_BUF_TEXEL_STORAGE
PL_BUF_PRIVATE, // GPU-private usage (interpretation arbitrary)
PL_BUF_TYPE_COUNT,
};
// Structure describing a buffer.
struct pl_buf_params {
enum pl_buf_type type;
size_t size; // size in bytes
bool host_mapped; // create a persistent, RW mapping (pl_buf.data)
bool host_writable; // contents may be updated via pl_buf_write()
bool host_readable; // contents may be read back via pl_buf_read()
// For texel buffers (PL_BUF_TEXEL_*), this gives the interpretation of the
// buffer's contents. `format->caps` must include the corresponding
// PL_FMT_CAP_TEXEL_* for the texel buffer type in use.
const struct pl_fmt *format;
// If non-NULL, the buffer will be created with these contents. Otherwise,
// the initial data is undefined. Using this does *not* require setting
// host_writable.
const void *initial_data;
};
// A generic buffer, which can be used for multiple purposes (texture transfer,
// storage buffer, uniform buffer, etc.)
//
// Note on efficiency: A pl_buf does not necessarily represent a true "buffer"
// object on the underlying graphics API. It may also refer to a sub-slice of
// a larger buffer, depending on the implementation details of the GPU. The
// bottom line is that users do not need to worry about the efficiency of using
// many small pl_buf objects. Having many small pl_bufs, even lots of few-byte
// vertex buffers, is designed to be completely fine.
struct pl_buf {
struct pl_buf_params params;
char *data; // for persistently mapped buffers, points to the first byte
void *priv;
};
// Create a buffer. The type of buffer depends on the parameters. The buffer
// parameters must adhere to the restrictions imposed by the pl_gpu_limits.
// Returns NULL on failure.
const struct pl_buf *pl_buf_create(const struct pl_gpu *gpu,
const struct pl_buf_params *params);
void pl_buf_destroy(const struct pl_gpu *gpu, const struct pl_buf **buf);
// Update the contents of a buffer, starting at a given offset (must be a
// multiple of 4) and up to a given size, with the contents of *data.
void pl_buf_write(const struct pl_gpu *gpu, const struct pl_buf *buf,
size_t buf_offset, const void *data, size_t size);
// Read back the contents of a buffer, starting at a given offset (must be a
// multiple of 4) and up to a given size, storing the data into *dest.
// Returns whether successful.
bool pl_buf_read(const struct pl_gpu *gpu, const struct pl_buf *buf,
size_t buf_offset, void *dest, size_t size);
// Returns whether or not a buffer is currently "in use". This can either be
// because of a pending read operation or because of a pending write operation.
// Coalescing multiple types of the same access (e.g. uploading the same buffer
// to multiple textures) is fine, but trying to read a buffer while it is being
// written to or trying to write to a buffer while it is being read from will
// almost surely result in graphical corruption. The GPU makes no attempt to
// enforce this, it is up to the user to check and adhere to whatever
// restrictions are necessary.
//
// The `timeout`, specified in nanoseconds, indicates how long to block for
// before returning. If set to 0, this function will never block, and only
// returns the current status of the buffer. The actual precision of the
// timeout may be significantly longer than one nanosecond, and has no upper
// bound. This function does not provide hard latency guarantees.
//
// Note: Destroying a buffer (pl_buf_destroy) is always valid, even if that
// buffer is in use.
bool pl_buf_poll(const struct pl_gpu *gpu, const struct pl_buf *buf, uint64_t timeout);
// Data type of a shader input variable (e.g. uniform, or UBO member)
enum pl_var_type {
PL_VAR_INVALID = 0,
PL_VAR_SINT, // C: int GLSL: int/ivec
PL_VAR_UINT, // C: unsigned int GLSL: uint/uvec
PL_VAR_FLOAT, // C: float GLSL: float/vec/mat
PL_VAR_TYPE_COUNT
};
// Returns the host size (in bytes) of a pl_var_type.
size_t pl_var_type_size(enum pl_var_type type);
// Represents a shader input variable (concrete data, e.g. vector, matrix)
struct pl_var {
const char *name; // name as used in the shader
enum pl_var_type type;
// The total number of values is given by dim_v * dim_m. For example, a
// vec2 would have dim_v = 2 and dim_m = 1. A mat3x4 would have dim_v = 4
// and dim_m = 3.
int dim_v; // vector dimension
int dim_m; // matrix dimension (number of columns, see below)
int dim_a; // array dimension
};
// Returns a GLSL type name (e.g. vec4) for a given pl_var, or NULL if the
// variable is not legal. Not that the array dimension is ignored, since the
// array dimension is usually part of the variable name and not the type name.
const char *pl_var_glsl_type_name(struct pl_var var);
// Helper functions for constructing the most common pl_vars.
struct pl_var pl_var_uint(const char *name);
struct pl_var pl_var_float(const char *name);
struct pl_var pl_var_vec2(const char *name);
struct pl_var pl_var_vec3(const char *name);
struct pl_var pl_var_vec4(const char *name);
struct pl_var pl_var_mat2(const char *name);
struct pl_var pl_var_mat3(const char *name);
struct pl_var pl_var_mat4(const char *name);
// Converts a pl_fmt to an "equivalent" pl_var. Equivalent in this sense means
// that the pl_var's type will be the same as the vertex's sampled type (e.g.
// PL_FMT_UNORM gets turned into PL_VAR_FLOAT).
struct pl_var pl_var_from_fmt(const struct pl_fmt *fmt, const char *name);
// Describes the memory layout of a variable, relative to some starting location
// (typically the offset within a uniform/storage/pushconstant buffer)
//
// Note on matrices: All GPUs expect column major matrices, for both buffers and
// input variables. Care needs to be taken to avoid trying to use e.g. a
// pl_matrix3x3 (which is row major) directly as a pl_var_update.data!
//
// In terms of the host layout, a column-major matrix (e.g. matCxR) with C
// columns and R rows is treated like an array vecR[C]. The `stride` here refers
// to the separation between these array elements, i.e. the separation between
// the individual columns.
//
// Visualization of a mat4x3:
//
// 0 1 2 3 <- columns
// 0 [ (A) (D) (G) (J) ]
// 1 [ (B) (E) (H) (K) ]
// 2 [ (C) (F) (I) (L) ]
// ^ rows
//
// Layout in GPU memory: (stride=16, size=60)
//
// [ A B C ] X <- column 0, offset +0
// [ D E F ] X <- column 1, offset +16
// [ G H I ] X <- column 2, offset +32
// [ J K L ] <- column 3, offset +48
//
// Note the lack of padding on the last column in this example.
// In general: size <= stride * dim_m
//
// C representation: (stride=12, size=48)
//
// { { A, B, C },
// { D, E, F },
// { G, H, I },
// { J, K, L } }
//
// Note on arrays: `stride` represents both the stride between elements of a
// matrix, and the stride between elements of an array. That is, there is no
// distinction between the columns of a matrix and the rows of an array. For
// example, a mat2[10] and a vec2[20] share the same pl_var_layout - the stride
// would be sizeof(vec2) and the size would be sizeof(vec2) * 2 * 10.
struct pl_var_layout {
size_t offset; // the starting offset of the first byte
size_t stride; // the delta between two elements of an array/matrix
size_t size; // the total size of the input
};
// Returns the host layout of an input variable as required for a
// tightly-packed, byte-aligned C data type, given a starting offset.
struct pl_var_layout pl_var_host_layout(size_t offset, const struct pl_var *var);
// Returns the layout requirements of a uniform buffer element given a current
// buffer offset. If limits.max_ubo_size is 0, then this function returns {0}.
//
// Note: In terms of the GLSL, this is always *specified* as std140 layout, but
// because of the way GLSL gets translated to other APIs (notably D3D11), the
// actual buffer contents may vary considerably from std140. As such, the
// calling code should not make any assumptions about the buffer layout and
// instead query the layout requirements explicitly using this function.
//
// The normal way to use this function is when calculating the size and offset
// requirements of a uniform buffer in an incremental fashion, to calculate the
// new offset of the next variable in this buffer.
struct pl_var_layout pl_buf_uniform_layout(const struct pl_gpu *gpu, size_t offset,
const struct pl_var *var);
// Returns the layout requirements of a storage buffer element given a current
// buffer offset. If limits.max_ssbo_size is 0, then this function returns {0}.
//
// Note: In terms of the GLSL, this is always *specified* as std430 layout, but
// like with pl_buf_uniform_layout, the actual implementation may disagree.
struct pl_var_layout pl_buf_storage_layout(const struct pl_gpu *gpu, size_t offset,
const struct pl_var *var);
// Returns the layout requirements of a push constant element given a current
// push constant offset. If `gpu->limits.max_pushc_size` is 0, then this
// function returns {0}.
struct pl_var_layout pl_push_constant_layout(const struct pl_gpu *gpu, size_t offset,
const struct pl_var *var);
// Like memcpy, but copies bytes from `src` to `dst` in a manner governed by
// the stride and size of `dst_layout` as well as `src_layout`. Also takes
// into account the respective `offset`.
void memcpy_layout(void *dst, struct pl_var_layout dst_layout,
const void *src, struct pl_var_layout src_layout);
// Represents a vertex attribute.
struct pl_vertex_attrib {
const char *name; // name as used in the shader
const struct pl_fmt *fmt; // data format (must have PL_FMT_CAP_VERTEX)
size_t offset; // byte offset into the vertex struct
int location; // vertex location (as used in the shader)
};
// Type of a shader input descriptor.
enum pl_desc_type {
PL_DESC_INVALID = 0,
PL_DESC_SAMPLED_TEX, // C: pl_tex* GLSL: combined texture sampler
// (pl_tex->params.sampleable must be set)
PL_DESC_STORAGE_IMG, // C: pl_tex* GLSL: storage image
// (pl_tex->params.storable must be set)
PL_DESC_BUF_UNIFORM, // C: pl_buf* GLSL: uniform buffer
// (pl_buf->params.type must be PL_BUF_UNIFORM)
PL_DESC_BUF_STORAGE, // C: pl_buf* GLSL: storage buffer
// (pl_buf->params.type must be PL_BUF_STORAGE)
PL_DESC_BUF_TEXEL_UNIFORM,// C: pl_buf* GLSL: uniform samplerBuffer
// (pl_buf->params.type must be PL_BUF_TEXEL_UNIFORM)
PL_DESC_BUF_TEXEL_STORAGE,// C: pl_buf* GLSL: uniform imageBuffer
// (pl_buf->params.type must be PL_BUF_TEXEL_STORAGE)
PL_DESC_TYPE_COUNT
};
// Returns an abstract namespace index for a given descriptor type. This will
// always be a value >= 0 and < PL_DESC_TYPE_COUNT. Implementations can use
// this to figure out which descriptors may share the same value of `binding`.
// Bindings must only be unique for all descriptors within the same namespace.
int pl_desc_namespace(const struct pl_gpu *gpu, enum pl_desc_type type);
// Access mode of a shader input descriptor.
enum pl_desc_access {
PL_DESC_ACCESS_READWRITE,
PL_DESC_ACCESS_READONLY,
PL_DESC_ACCESS_WRITEONLY,
};
// Returns the GLSL syntax for a given access mode (e.g. "readonly").
const char *pl_desc_access_glsl_name(enum pl_desc_access mode);
struct pl_buffer_var {
struct pl_var var;
struct pl_var_layout layout;
};
// Represents a shader descriptor (e.g. texture or buffer binding)
struct pl_desc {
const char *name; // name as used in the shader
enum pl_desc_type type;
// The binding of this descriptor, as used in the shader. All bindings
// within a namespace must be unique. (see: pl_desc_namespace)
int binding;
// For storage images and storage buffers, this can be used to restrict
// the type of access that may be performed on the descriptor. Ignored for
// the other descriptor types (uniform buffers and sampled textures are
// always read-only).
enum pl_desc_access access;
// For PL_DESC_BUF_UNIFORM/STORAGE, this specifies the layout of the
// variables contained by a buffer. Ignored for the other descriptor types
struct pl_buffer_var *buffer_vars;
int num_buffer_vars;
};
// Framebuffer blending mode (for raster passes)
enum pl_blend_mode {
PL_BLEND_ZERO,
PL_BLEND_ONE,
PL_BLEND_SRC_ALPHA,
PL_BLEND_ONE_MINUS_SRC_ALPHA,
};
struct pl_blend_params {
enum pl_blend_mode src_rgb;
enum pl_blend_mode dst_rgb;
enum pl_blend_mode src_alpha;
enum pl_blend_mode dst_alpha;
};
enum pl_prim_type {
PL_PRIM_TRIANGLE_LIST,
PL_PRIM_TRIANGLE_STRIP,
PL_PRIM_TRIANGLE_FAN,
};
enum pl_pass_type {
PL_PASS_INVALID = 0,
PL_PASS_RASTER, // vertex+fragment shader
PL_PASS_COMPUTE, // compute shader (requires PL_GPU_CAP_COMPUTE)
PL_PASS_TYPE_COUNT,
};
// Description of a rendering pass. It conflates the following:
// - GLSL shader(s) and its list of inputs
// - target parameters (for raster passes)
struct pl_pass_params {
enum pl_pass_type type;
// Input variables. Only supported if PL_GPU_CAP_INPUT_VARIABLES is set.
// Otherwise, num_variables must be 0.
struct pl_var *variables;
int num_variables;
// Input descriptors. (Always supported)
struct pl_desc *descriptors;
int num_descriptors;
// Push constant region. Must be be a multiple of 4 <= limits.max_pushc_size
size_t push_constants_size;
// The shader text in GLSL. For PL_PASS_RASTER, this is interpreted
// as a fragment shader. For PL_PASS_COMPUTE, this is interpreted as
// a compute shader.
const char *glsl_shader;
// Highly implementation-specific byte array storing a compiled version of
// the same shader. Can be used to speed up pass creation on already
// known/cached shaders.
//
// Note: There are no restrictions on this. Passing an out-of-date cache,
// passing a cache corresponding to a different progam, or passing a cache
// belonging to a different GPU, are all valid. But obviously, in such cases,
// there is no benefit in doing so.
const uint8_t *cached_program;
size_t cached_program_len;
// --- type==PL_PASS_RASTER only
// Describes the interpretation and layout of the vertex data.
enum pl_prim_type vertex_type;
struct pl_vertex_attrib *vertex_attribs;
int num_vertex_attribs;
size_t vertex_stride;
// The vertex shader itself.
const char *vertex_shader;
// The target dummy texture this renderpass is intended to be used with.
// This doesn't have to be a real texture - the caller can also pass a
// blank pl_tex object, as long as target_dummy.params.format is set. The
// format must support PL_FMT_CAP_RENDERABLE, and the target dummy must
// have `renderable` enabled.
//
// If you pass a real texture here, the GPU backend may be able to optimize
// the render pass better for the specific requirements of this texture.
// This does not change the semantics of pl_pass_run, just perhaps the
// performance. (The `priv` pointer will be cleared by pl_pass_create, so
// there is no risk of a dangling reference)
struct pl_tex target_dummy;
// Target blending mode. If this is NULL, blending is disabled. Otherwise,
// the `target_dummy.params.format` must have PL_FMT_CAP_BLENDABLE.
const struct pl_blend_params *blend_params;
// If false, the target's existing contents will be discarded before the
// pass is run. (Semantically equivalent to calling pl_tex_invalidate
// before every pl_pass_run, but slightly more efficient)
bool load_target;
};
// Conflates the following typical GPU API concepts:
// - various kinds of shaders
// - rendering pipelines
// - descriptor sets, uniforms, other bindings
// - all synchronization necessary
// - the current values of all inputs
struct pl_pass {
struct pl_pass_params params;
void *priv;
};
// Compile a shader and create a render pass. This is a rare/expensive
// operation and may take a significant amount of time, even if a cached
// program is used. Returns NULL on failure.
//
// The resulting pl_pass->params.cached_program will be initialized by
// this function to point to a new, valid cached program (if any).
const struct pl_pass *pl_pass_create(const struct pl_gpu *gpu,
const struct pl_pass_params *params);
void pl_pass_destroy(const struct pl_gpu *gpu, const struct pl_pass **pass);
struct pl_desc_binding {
const void *object; // pl_* object with type corresponding to pl_desc_type
};
struct pl_var_update {
int index; // index into params.variables[]
const void *data; // pointer to raw byte data corresponding to pl_var_host_layout()
};
struct pl_pass_run_params {
const struct pl_pass *pass;
// This list only contains descriptors/variables which have changed
// since the previous invocation. All non-mentioned variables implicitly
// preserve their state from the last invocation.
struct pl_var_update *var_updates;
int num_var_updates;
// This list contains all descriptors used by this pass. It must
// always be filled, even if the descriptors haven't changed. The order
// must match that of pass->params.descriptors
struct pl_desc_binding *desc_bindings;
// The push constants for this invocation. This must always be set and
// fully defined for every invocation if params.push_constants_size > 0.
void *push_constants;
// --- pass->params.type==PL_PASS_RASTER only
// Target must be a 2D texture, target->params.renderable must be true, and
// target->params.format must match pass->params.target_fmt. If the viewport
// or scissors are left blank, they are inferred from target->params.
//
// WARNING: Rendering to a *target that is being read from by the same
// shader is undefined behavior. In general, trying to bind the same
// resource multiple times to the same shader is undefined behavior.
const struct pl_tex *target;
struct pl_rect2d viewport; // screen space viewport (must be normalized)
struct pl_rect2d scissors; // target render scissors (must be normalized)
void *vertex_data; // raw pointer to vertex data
int vertex_count; // number of vertices to render
// --- pass->params.type==PL_PASS_COMPUTE only
// Number of work groups to dispatch per dimension (X/Y/Z). Must be <= the
// corresponding index of limits.max_dispatch
int compute_groups[3];
};
// Execute a render pass.
void pl_pass_run(const struct pl_gpu *gpu, const struct pl_pass_run_params *params);
// This is semantically a no-op, but it provides a hint that you want to flush
// any partially queued up commands and begin execution. There is normally no
// need to call this, because queued commands will always be implicitly flushed
// whenever necessary to make forward progress on commands like `pl_buf_poll`,
// or when submitting a frame to a swapchain for display. In fact, calling this
// function can negatively impact performance, because some GPUs rely on being
// able to re-order and modify queued commands in order to enable optimizations
// retroactively.
//
// The only time this might be beneficial to call explicitly is if you're doing
// lots of offline rendering over a long period of time, and only fetching the
// results (via pl_tex_download) at the very end.
void pl_gpu_flush(const struct pl_gpu *gpu);
#endif // LIBPLACEBO_GPU_H_
|