vo_opengl: refactor into vo_gpu

This is done in several steps:

1. refactor MPGLContext -> struct ra_ctx
2. move GL-specific stuff in vo_opengl into opengl/context.c
3. generalize context creation to support other APIs, and add --gpu-api
4. rename all of the --opengl- options that are no longer opengl-specific
5. move all of the stuff from opengl/* that isn't GL-specific into gpu/
   (note: opengl/gl_utils.h became opengl/utils.h)
6. rename vo_opengl to vo_gpu
7. to handle window screenshots, the short-term approach was to just add
   it to ra_swchain_fns. Long term (and for vulkan) this has to be moved to
   ra itself (and vo_gpu altered to compensate), but this was a stop-gap
   measure to prevent this commit from getting too big
8. move ra->fns->flush to ra_gl_ctx instead
9. some other minor changes that I've probably already forgotten

Note: This is one half of a major refactor, the other half of which is
provided by rossy's following commit. This commit enables support for
all linux platforms, while his version enables support for all non-linux
platforms.

Note 2: vo_opengl_cb.c also re-uses ra_gl_ctx so it benefits from the
--opengl- options like --opengl-early-flush, --opengl-finish etc. Should
be a strict superset of the old functionality.

Disclaimer: Since I have no way of compiling mpv on all platforms, some
of these ports were done blindly. Specifically, the blind ports included
context_mali_fbdev.c and context_rpi.c. Since they're both based on
egl_helpers, the port should have gone smoothly without any major
changes required. But if somebody complains about a compile error on
those platforms (assuming anybody actually uses them), you know where to
complain.

1 files changed, 488 insertions, 0 deletions

diff --git a/video/out/gpu/ra.h b/video/out/gpu/ra.h
new file mode 100644
index 0000000000..76f98397f8
--- /dev/null
+++ b/video/out/gpu/ra.h
@@ -0,0 +1,488 @@
+#pragma once
+
+#include "common/common.h"
+#include "misc/bstr.h"
+
+// Handle for a rendering API backend.
+struct ra {
+    struct ra_fns *fns;
+    void *priv;
+
+    int glsl_version;       // GLSL version (e.g. 300 => 3.0)
+    bool glsl_es;           // use ES dialect
+    bool glsl_vulkan;       // use vulkan dialect
+
+    struct mp_log *log;
+
+    // RA_CAP_* bit field. The RA backend must set supported features at init
+    // time.
+    uint64_t caps;
+
+    // Maximum supported width and height of a 2D texture. Set by the RA backend
+    // at init time.
+    int max_texture_wh;
+
+    // Maximum shared memory for compute shaders. Set by the RA backend at init
+    // time.
+    size_t max_shmem;
+
+    // Set of supported texture formats. Must be added by RA backend at init time.
+    // If there are equivalent formats with different caveats, the preferred
+    // formats should have a lower index. (E.g. GLES3 should put rg8 before la.)
+    struct ra_format **formats;
+    int num_formats;
+
+    // Accelerate texture uploads via an extra PBO even when
+    // RA_CAP_DIRECT_UPLOAD is supported. This is basically only relevant for
+    // OpenGL. Set by the RA user.
+    bool use_pbo;
+};
+
+enum {
+    RA_CAP_TEX_1D         = 1 << 0, // supports 1D textures (as shader inputs)
+    RA_CAP_TEX_3D         = 1 << 1, // supports 3D textures (as shader inputs)
+    RA_CAP_BLIT           = 1 << 2, // supports ra_fns.blit
+    RA_CAP_COMPUTE        = 1 << 3, // supports compute shaders
+    RA_CAP_DIRECT_UPLOAD  = 1 << 4, // supports tex_upload without ra_buf
+    RA_CAP_BUF_RO         = 1 << 5, // supports RA_VARTYPE_BUF_RO
+    RA_CAP_BUF_RW         = 1 << 6, // supports RA_VARTYPE_BUF_RW
+    RA_CAP_NESTED_ARRAY   = 1 << 7, // supports nested arrays
+    RA_CAP_SHARED_BINDING = 1 << 8, // sampler/image/buffer namespaces are disjoint
+    RA_CAP_GLOBAL_UNIFORM = 1 << 9, // supports using "naked" uniforms (not UBO)
+};
+
+enum ra_ctype {
+    RA_CTYPE_UNKNOWN = 0,   // also used for inconsistent multi-component formats
+    RA_CTYPE_UNORM,         // unsigned normalized integer (fixed point) formats
+    RA_CTYPE_UINT,          // full integer formats
+    RA_CTYPE_FLOAT,         // float formats (signed, any bit size)
+};
+
+// All formats must be useable as texture formats. All formats must be byte
+// aligned (all pixels start and end on a byte boundary), at least as far CPU
+// transfers are concerned.
+struct ra_format {
+    // All fields are read-only after creation.
+    const char *name;       // symbolic name for user interaction/debugging
+    void *priv;
+    enum ra_ctype ctype;    // data type of each component
+    bool ordered;           // components are sequential in memory, and returned
+                            // by the shader in memory order (the shader can
+                            // return arbitrary values for unused components)
+    int num_components;     // component count, 0 if not applicable, max. 4
+    int component_size[4];  // in bits, all entries 0 if not applicable
+    int component_depth[4]; // bits in use for each component, 0 if not applicable
+                            // (_must_ be set if component_size[] includes padding,
+                            //  and the real procession as seen by shader is lower)
+    int pixel_size;         // in bytes, total pixel size (0 if opaque)
+    bool luminance_alpha;   // pre-GL_ARB_texture_rg hack for 2 component textures
+                            // if this is set, shader must use .ra instead of .rg
+                            // only applies to 2-component textures
+    bool linear_filter;     // linear filtering available from shader
+    bool renderable;        // can be used for render targets
+
+    // If not 0, the format represents some sort of packed fringe format, whose
+    // shader representation is given by the special_imgfmt_desc pointer.
+    int special_imgfmt;
+    const struct ra_imgfmt_desc *special_imgfmt_desc;
+};
+
+struct ra_tex_params {
+    int dimensions;         // 1-3 for 1D-3D textures
+    // Size of the texture. 1D textures require h=d=1, 2D textures require d=1.
+    int w, h, d;
+    const struct ra_format *format;
+    bool render_src;        // must be useable as source texture in a shader
+    bool render_dst;        // must be useable as target texture in a shader
+    bool storage_dst;       // must be usable as a storage image (RA_VARTYPE_IMG_W)
+    bool blit_src;          // must be usable as a blit source
+    bool blit_dst;          // must be usable as a blit destination
+    bool host_mutable;      // texture may be updated with tex_upload
+    // When used as render source texture.
+    bool src_linear;        // if false, use nearest sampling (whether this can
+                            // be true depends on ra_format.linear_filter)
+    bool src_repeat;        // if false, clamp texture coordinates to edge
+                            // if true, repeat texture coordinates
+    bool non_normalized;    // hack for GL_TEXTURE_RECTANGLE OSX idiocy
+                            // always set to false, except in OSX code
+    bool external_oes;      // hack for GL_TEXTURE_EXTERNAL_OES idiocy
+    // If non-NULL, the texture will be created with these contents. Using
+    // this does *not* require setting host_mutable. Otherwise, the initial
+    // data is undefined.
+    void *initial_data;
+};
+
+// 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.
+struct ra_tex {
+    // All fields are read-only after creation.
+    struct ra_tex_params params;
+    void *priv;
+};
+
+struct ra_tex_upload_params {
+    struct ra_tex *tex; // Texture to upload to
+    bool invalidate;    // Discard pre-existing data not in the region uploaded
+    // Uploading from buffer:
+    struct ra_buf *buf; // Buffer to upload from (mutually exclusive with `src`)
+    size_t buf_offset;  // Start of data within buffer (bytes)
+    // Uploading directly: (Note: If RA_CAP_DIRECT_UPLOAD is not set, then this
+    // will be internally translated to a tex_upload buffer by the RA)
+    const void *src;    // Address of data
+    // For 2D textures only:
+    struct mp_rect *rc; // Region to upload. NULL means entire image
+    ptrdiff_t stride;   // The size of a horizontal line in bytes (*not* texels!)
+};
+
+// Buffer type hint. Setting this may result in more or less efficient
+// operation, although it shouldn't technically prohibit anything
+enum ra_buf_type {
+    RA_BUF_TYPE_INVALID,
+    RA_BUF_TYPE_TEX_UPLOAD,     // texture upload buffer (pixel buffer object)
+    RA_BUF_TYPE_SHADER_STORAGE, // shader buffer (SSBO), for RA_VARTYPE_BUF_RW
+    RA_BUF_TYPE_UNIFORM,        // uniform buffer (UBO), for RA_VARTYPE_BUF_RO
+};
+
+struct ra_buf_params {
+    enum ra_buf_type type;
+    size_t size;
+    bool host_mapped;  // create a read-writable persistent mapping (ra_buf.data)
+    bool host_mutable; // contents may be updated via buf_update()
+    // If non-NULL, the buffer will be created with these contents. Otherwise,
+    // the initial data is undefined.
+    void *initial_data;
+};
+
+// A generic buffer, which can be used for many purposes (texture upload,
+// storage buffer, uniform buffer, etc.)
+struct ra_buf {
+    // All fields are read-only after creation.
+    struct ra_buf_params params;
+    void *data; // for persistently mapped buffers, points to the first byte
+    void *priv;
+};
+
+// Type of a shader uniform variable, or a vertex attribute. In all cases,
+// vectors are matrices are done by having more than 1 value.
+enum ra_vartype {
+    RA_VARTYPE_INVALID,
+    RA_VARTYPE_INT,             // C: int, GLSL: int, ivec*
+    RA_VARTYPE_FLOAT,           // C: float, GLSL: float, vec*, mat*
+    RA_VARTYPE_TEX,             // C: ra_tex*, GLSL: various sampler types
+                                // ra_tex.params.render_src must be true
+    RA_VARTYPE_IMG_W,           // C: ra_tex*, GLSL: various image types
+                                // write-only (W) image for compute shaders
+                                // ra_tex.params.storage_dst must be true
+    RA_VARTYPE_BYTE_UNORM,      // C: uint8_t, GLSL: int, vec* (vertex data only)
+    RA_VARTYPE_BUF_RO,          // C: ra_buf*, GLSL: uniform buffer block
+                                // buf type must be RA_BUF_TYPE_UNIFORM
+    RA_VARTYPE_BUF_RW,          // C: ra_buf*, GLSL: shader storage buffer block
+                                // buf type must be RA_BUF_TYPE_SHADER_STORAGE
+    RA_VARTYPE_COUNT
+};
+
+// Returns the host size of a ra_vartype, or 0 for abstract vartypes (e.g. tex)
+size_t ra_vartype_size(enum ra_vartype type);
+
+// Represents a uniform, texture input parameter, and similar things.
+struct ra_renderpass_input {
+    const char *name;       // name as used in the shader
+    enum ra_vartype type;
+    // The total number of values is given by dim_v * dim_m.
+    int dim_v;              // vector dimension (1 for non-vector and non-matrix)
+    int dim_m;              // additional matrix dimension (dim_v x dim_m)
+    // Vertex data: byte offset of the attribute into the vertex struct
+    size_t offset;
+    // RA_VARTYPE_TEX: texture unit
+    // RA_VARTYPE_IMG_W: image unit
+    // RA_VARTYPE_BUF_* buffer binding point
+    // Other uniforms: unused
+    // If RA_CAP_SHARED_BINDING is set, these may only be unique per input type.
+    // Otherwise, these must be unique for all input values.
+    int binding;
+};
+
+// Represents the layout requirements of an input value
+struct ra_layout {
+    size_t align;  // the alignment requirements (always a power of two)
+    size_t stride; // the delta between two rows of an array/matrix
+    size_t size;   // the total size of the input
+};
+
+// Returns the host layout of a render pass input. Returns {0} for renderpass
+// inputs without a corresponding host representation (e.g. textures/buffers)
+struct ra_layout ra_renderpass_input_layout(struct ra_renderpass_input *input);
+
+enum ra_blend {
+    RA_BLEND_ZERO,
+    RA_BLEND_ONE,
+    RA_BLEND_SRC_ALPHA,
+    RA_BLEND_ONE_MINUS_SRC_ALPHA,
+};
+
+enum ra_renderpass_type {
+    RA_RENDERPASS_TYPE_INVALID,
+    RA_RENDERPASS_TYPE_RASTER,  // vertex+fragment shader
+    RA_RENDERPASS_TYPE_COMPUTE, // compute shader
+};
+
+// Static part of a rendering pass. It conflates the following:
+//  - compiled shader and its list of uniforms
+//  - vertex attributes and its shader mappings
+//  - blending parameters
+// (For Vulkan, this would be shader module + pipeline state.)
+// Upon creation, the values of dynamic values such as uniform contents (whose
+// initial values are not provided here) are required to be 0.
+struct ra_renderpass_params {
+    enum ra_renderpass_type type;
+
+    // Uniforms, including texture/sampler inputs.
+    struct ra_renderpass_input *inputs;
+    int num_inputs;
+
+    // Highly implementation-specific byte array storing a compiled version
+    // of the program. Can be used to speed up shader compilation. A backend
+    // xan read this in renderpass_create, or set this on the newly created
+    // ra_renderpass params field.
+    bstr cached_program;
+
+    // --- type==RA_RENDERPASS_TYPE_RASTER only
+
+    // Describes the format of the vertex data. When using ra.glsl_vulkan,
+    // the order of this array must match the vertex attribute locations.
+    struct ra_renderpass_input *vertex_attribs;
+    int num_vertex_attribs;
+    int vertex_stride;
+
+    // Format of the target texture
+    const struct ra_format *target_format;
+
+    // Shader text, in GLSL. (Yes, you need a GLSL compiler.)
+    // These are complete shaders, including prelude and declarations.
+    const char *vertex_shader;
+    const char *frag_shader;
+
+    // Target blending mode. If enable_blend is false, the blend_ fields can
+    // be ignored.
+    bool enable_blend;
+    enum ra_blend blend_src_rgb;
+    enum ra_blend blend_dst_rgb;
+    enum ra_blend blend_src_alpha;
+    enum ra_blend blend_dst_alpha;
+
+    // --- type==RA_RENDERPASS_TYPE_COMPUTE only
+
+    // Shader text, like vertex_shader/frag_shader.
+    const char *compute_shader;
+};
+
+struct ra_renderpass_params *ra_renderpass_params_copy(void *ta_parent,
+        const struct ra_renderpass_params *params);
+
+// 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 uniforms (this one makes it relatively stateful
+//   from an API perspective)
+struct ra_renderpass {
+    // All fields are read-only after creation.
+    struct ra_renderpass_params params;
+    void *priv;
+};
+
+// An input value (see ra_renderpass_input).
+struct ra_renderpass_input_val {
+    int index;  // index into ra_renderpass_params.inputs[]
+    void *data; // pointer to data according to ra_renderpass_input
+                // (e.g. type==RA_VARTYPE_FLOAT+dim_v=3,dim_m=3 => float[9])
+};
+
+// Parameters for performing a rendering pass (basically the dynamic params).
+// These change potentially every time.
+struct ra_renderpass_run_params {
+    struct ra_renderpass *pass;
+
+    // Generally this lists parameters only which changed since the last
+    // invocation and need to be updated. The ra_renderpass instance is
+    // supposed to keep unchanged values from the previous run.
+    // For non-primitive types like textures, these entries are always added,
+    // even if they do not change.
+    struct ra_renderpass_input_val *values;
+    int num_values;
+
+    // --- pass->params.type==RA_RENDERPASS_TYPE_RASTER only
+
+    // target->params.render_dst must be true, and target->params.format must
+    // match pass->params.target_format.
+    struct ra_tex *target;
+    struct mp_rect viewport;
+    struct mp_rect scissors;
+
+    // (The primitive type is always a triangle list.)
+    void *vertex_data;
+    int vertex_count;   // number of vertex elements, not bytes
+
+    // --- pass->params.type==RA_RENDERPASS_TYPE_COMPUTE only
+
+    // Number of work groups to be run in X/Y/Z dimensions.
+    int compute_groups[3];
+};
+
+// This is an opaque type provided by the implementation, but we want to at
+// least give it a saner name than void* for code readability purposes.
+typedef void ra_timer;
+
+// Rendering API entrypoints. (Note: there are some additional hidden features
+// you need to take care of. For example, hwdec mapping will be provided
+// separately from ra, but might need to call into ra private code.)
+struct ra_fns {
+    void (*destroy)(struct ra *ra);
+
+    // Create a texture (with undefined contents). Return NULL on failure.
+    // This is a rare operation, and normally textures and even FBOs for
+    // temporary rendering intermediate data are cached.
+    struct ra_tex *(*tex_create)(struct ra *ra,
+                                 const struct ra_tex_params *params);
+
+    void (*tex_destroy)(struct ra *ra, struct ra_tex *tex);
+
+    // Upload data to a texture. This is an extremely common operation. When
+    // using a buffer, the contants of the buffer must exactly match the image
+    // - conversions between bit depth etc. are not supported. The buffer *may*
+    // be marked as "in use" while this operation is going on, and the contents
+    // must not be touched again by the API user until buf_poll returns true.
+    // Returns whether successful.
+    bool (*tex_upload)(struct ra *ra, const struct ra_tex_upload_params *params);
+
+    // Create a buffer. This can be used as a persistently mapped buffer,
+    // a uniform buffer, a shader storage buffer or possibly others.
+    // Not all usage types must be supported; may return NULL if unavailable.
+    struct ra_buf *(*buf_create)(struct ra *ra,
+                                 const struct ra_buf_params *params);
+
+    void (*buf_destroy)(struct ra *ra, struct ra_buf *buf);
+
+    // Update the contents of a buffer, starting at a given offset and up to a
+    // given size, with the contents of *data. This is an extremely common
+    // operation. Calling this while the buffer is considered "in use" is an
+    // error. (See: buf_poll)
+    void (*buf_update)(struct ra *ra, struct ra_buf *buf, ptrdiff_t offset,
+                       const void *data, size_t size);
+
+    // Returns if a buffer is currently "in use" or not. Updating the contents
+    // of a buffer (via buf_update or writing to buf->data) while it is still
+    // in use is an error and may result in graphical corruption. Optional, if
+    // NULL then all buffers are always usable.
+    bool (*buf_poll)(struct ra *ra, struct ra_buf *buf);
+
+    // Returns the layout requirements of a uniform buffer element. Optional,
+    // but must be implemented if RA_CAP_BUF_RO is supported.
+    struct ra_layout (*uniform_layout)(struct ra_renderpass_input *inp);
+
+    // Clear the dst with the given color (rgba) and within the given scissor.
+    // dst must have dst->params.render_dst==true. Content outside of the
+    // scissor is preserved.
+    void (*clear)(struct ra *ra, struct ra_tex *dst, float color[4],
+                  struct mp_rect *scissor);
+
+    // Copy a sub-rectangle from one texture to another. The source/dest region
+    // is always within the texture bounds. Areas outside the dest region are
+    // preserved. The formats of the textures must be losely compatible. The
+    // dst texture can be a swapchain framebuffer, but src can not. Only 2D
+    // textures are supported.
+    // The textures must have blit_src and blit_dst set, respectively.
+    // Rectangles with negative width/height lead to flipping, different src/dst
+    // sizes lead to point scaling. Coordinates are always in pixels.
+    // Optional. Only available if RA_CAP_BLIT is set (if it's not set, it must
+    // not be called, even if it's non-NULL).
+    void (*blit)(struct ra *ra, struct ra_tex *dst, struct ra_tex *src,
+                 struct mp_rect *dst_rc, struct mp_rect *src_rc);
+
+    // Compile a shader and create a pipeline. This is a rare operation.
+    // The params pointer and anything it points to must stay valid until
+    // renderpass_destroy.
+    struct ra_renderpass *(*renderpass_create)(struct ra *ra,
+                                    const struct ra_renderpass_params *params);
+
+    void (*renderpass_destroy)(struct ra *ra, struct ra_renderpass *pass);
+
+    // Perform a render pass, basically drawing a list of triangles to a FBO.
+    // This is an extremely common operation.
+    void (*renderpass_run)(struct ra *ra,
+                           const struct ra_renderpass_run_params *params);
+
+    // Create a timer object. Returns NULL on failure, or if timers are
+    // unavailable for some reason. Optional.
+    ra_timer *(*timer_create)(struct ra *ra);
+
+    void (*timer_destroy)(struct ra *ra, ra_timer *timer);
+
+    // Start recording a timer. Note that valid usage requires you to pair
+    // every start with a stop. Trying to start a timer twice, or trying to
+    // stop a timer before having started it, consistutes invalid usage.
+    void (*timer_start)(struct ra *ra, ra_timer *timer);
+
+    // Stop recording a timer. This also returns any results that have been
+    // measured since the last usage of this ra_timer. It's important to note
+    // that GPU timer measurement are asynchronous, so this function does not
+    // always produce a value - and the values it does produce are typically
+    // delayed by a few frames. When no value is available, this returns 0.
+    uint64_t (*timer_stop)(struct ra *ra, ra_timer *timer);
+
+    // Associates a marker with any past error messages, for debugging
+    // purposes. Optional.
+    void (*debug_marker)(struct ra *ra, const char *msg);
+};
+
+struct ra_tex *ra_tex_create(struct ra *ra, const struct ra_tex_params *params);
+void ra_tex_free(struct ra *ra, struct ra_tex **tex);
+
+struct ra_buf *ra_buf_create(struct ra *ra, const struct ra_buf_params *params);
+void ra_buf_free(struct ra *ra, struct ra_buf **buf);
+
+void ra_free(struct ra **ra);
+
+const struct ra_format *ra_find_unorm_format(struct ra *ra,
+                                             int bytes_per_component,
+                                             int n_components);
+const struct ra_format *ra_find_uint_format(struct ra *ra,
+                                            int bytes_per_component,
+                                            int n_components);
+const struct ra_format *ra_find_float16_format(struct ra *ra, int n_components);
+const struct ra_format *ra_find_named_format(struct ra *ra, const char *name);
+
+struct ra_imgfmt_desc {
+    int num_planes;
+    const struct ra_format *planes[4];
+    // Chroma pixel size (1x1 is 4:4:4)
+    uint8_t chroma_w, chroma_h;
+    // Component storage size in bits (possibly padded). For formats with
+    // different sizes per component, this is arbitrary. For padded formats
+    // like P010 or YUV420P10, padding is included.
+    int component_bits;
+    // Like mp_regular_imgfmt.component_pad.
+    int component_pad;
+    // For each texture and each texture output (rgba order) describe what
+    // component it returns.
+    // The values are like the values in mp_regular_imgfmt_plane.components[].
+    // Access as components[plane_nr][component_index]. Set unused items to 0.
+    // For ra_format.luminance_alpha, this returns 1/2 ("rg") instead of 1/4
+    // ("ra"). the logic is that the texture format has 2 channels, thus the
+    // data must be returned in the first two components. The renderer fixes
+    // this later.
+    uint8_t components[4][4];
+};
+
+bool ra_get_imgfmt_desc(struct ra *ra, int imgfmt, struct ra_imgfmt_desc *out);
+
+void ra_dump_tex_formats(struct ra *ra, int msgl);
+void ra_dump_imgfmt_desc(struct ra *ra, const struct ra_imgfmt_desc *desc,
+                         int msgl);
+void ra_dump_img_formats(struct ra *ra, int msgl);