文章目錄

• 1 概述
• 2 Context
• • 2.1 GLXContext
  • • • include/GL/glx.h
      • src/gallium/state_trackers/glx/xlib/glx_api.c
  • 2.2 XMesaContext
  • • • src/gallium/state_trackers/glx/xlib/xm_api.h
  • 2.3 gl_context
  • • • src/mesa/main/mtypes.h
  • 2.4 st_context
  • • • src/mesa/state_tracker/st_context.h
      • src/mesa/state_tracker/st_context.c
  • 2.5 pipe_context
  • • • src/gallium/include/pipe/p_context.h
• 3 Interface
• • 3.1 Device driver interfaces
  • • • src/mesa/main/mtypes.h
      • src/mesa/main/dd.h
      • src/mesa/drivers/common/driverfuncs.h
      • src/mesa/drivers/common/driverfuncs.c
      • src/mesa/state_tracker/st_cb_fbo.c

---

1 概述

Mesa的核心數據結構包含以下幾類：

• Context
• Interface

2 Context

2.1 GLXContext

include/GL/glx.h

typedef struct __GLXcontextRec *GLXContext;

src/gallium/state_trackers/glx/xlib/glx_api.c

/*** The GLXContext typedef is defined as a pointer to this structure.*/ struct __GLXcontextRec {Display *currentDpy;GLboolean isDirect;GLXDrawable currentDrawable;GLXDrawable currentReadable;XID xid;XMesaContext xmesaContext; };

2.2 XMesaContext

src/gallium/state_trackers/glx/xlib/xm_api.h

#include "main/mtypes.h" /* for gl_config */ #include "state_tracker/st_api.h" #include "os/os_thread.h"#include "state_tracker/xlibsw_api.h"# include <X11/Xlib.h> # include <X11/Xlibint.h> # include <X11/Xutil.h>struct hud_context;typedef struct xmesa_display *XMesaDisplay; typedef struct xmesa_buffer *XMesaBuffer; typedef struct xmesa_context *XMesaContext; typedef struct xmesa_visual *XMesaVisual;struct xmesa_display {mtx_t mutex;Display *display;struct pipe_screen *screen;struct st_manager *smapi;struct pipe_context *pipe; }; // 省略 /*** Context info, derived from st_context.* Basically corresponds to a GLXContext.*/ struct xmesa_context {struct st_context_iface *st;XMesaVisual xm_visual; /** pixel format info */XMesaBuffer xm_buffer; /** current drawbuffer */XMesaBuffer xm_read_buffer; /** current readbuffer */struct hud_context *hud; };

2.3 gl_context

src/mesa/main/mtypes.h

/*** Mesa rendering context.** This is the central context data structure for Mesa. Almost all* OpenGL state is contained in this structure.* Think of this as a base class from which device drivers will derive* sub classes.*/ struct gl_context {/** State possibly shared with other contexts in the address space */struct gl_shared_state *Shared;/** \name API function pointer tables *//*@{*/gl_api API;/*** The current dispatch table for non-displaylist-saving execution, either* BeginEnd or OutsideBeginEnd*/struct _glapi_table *Exec;/*** The normal dispatch table for non-displaylist-saving, non-begin/end*/struct _glapi_table *OutsideBeginEnd;/** The dispatch table used between glNewList() and glEndList() */struct _glapi_table *Save;/*** The dispatch table used between glBegin() and glEnd() (outside of a* display list). Only valid functions between those two are set, which is* mostly just the set in a GLvertexformat struct.*/struct _glapi_table *BeginEnd;/*** Dispatch table for when a graphics reset has happened.*/struct _glapi_table *ContextLost;/*** Dispatch table used to marshal API calls from the client program to a* separate server thread. NULL if API calls are not being marshalled to* another thread.*/struct _glapi_table *MarshalExec;/*** Dispatch table currently in use for fielding API calls from the client* program. If API calls are being marshalled to another thread, this ==* MarshalExec. Otherwise it == CurrentServerDispatch.*/struct _glapi_table *CurrentClientDispatch;/*** Dispatch table currently in use for performing API calls. == Save or* Exec.*/struct _glapi_table *CurrentServerDispatch;/*@}*/struct glthread_state *GLThread;struct gl_config Visual;struct gl_framebuffer *DrawBuffer; /**< buffer for writing */struct gl_framebuffer *ReadBuffer; /**< buffer for reading */struct gl_framebuffer *WinSysDrawBuffer; /**< set with MakeCurrent */struct gl_framebuffer *WinSysReadBuffer; /**< set with MakeCurrent *//*** Device driver function pointer table*/struct dd_function_table Driver;/** Core/Driver constants */struct gl_constants Const;/** \name The various 4x4 matrix stacks *//*@{*/struct gl_matrix_stack ModelviewMatrixStack;struct gl_matrix_stack ProjectionMatrixStack;struct gl_matrix_stack TextureMatrixStack[MAX_TEXTURE_UNITS];struct gl_matrix_stack ProgramMatrixStack[MAX_PROGRAM_MATRICES];struct gl_matrix_stack *CurrentStack; /**< Points to one of the above stacks *//*@}*/ // 省略 };

2.4 st_context

src/mesa/state_tracker/st_context.h

struct st_context {struct st_context_iface iface;struct gl_context *ctx;struct pipe_context *pipe;struct draw_context *draw; /**< For selection/feedback/rastpos only */struct draw_stage *feedback_stage; /**< For GL_FEEDBACK rendermode */struct draw_stage *selection_stage; /**< For GL_SELECT rendermode */struct draw_stage *rastpos_stage; /**< For glRasterPos */ // 省略 };

src/mesa/state_tracker/st_context.c

static void st_init_driver_functions(struct pipe_screen *screen,struct dd_function_table *functions) {_mesa_init_sampler_object_functions(functions);st_init_draw_functions(functions);st_init_blit_functions(functions);st_init_bufferobject_functions(screen, functions);st_init_clear_functions(functions);st_init_bitmap_functions(functions);st_init_copy_image_functions(functions);st_init_drawpixels_functions(functions);st_init_rasterpos_functions(functions);st_init_drawtex_functions(functions);st_init_eglimage_functions(functions);st_init_fbo_functions(functions); // 省略 }struct st_context * st_create_context(gl_api api, struct pipe_context *pipe,const struct gl_config *visual,struct st_context *share,const struct st_config_options *options,bool no_error) {struct gl_context *ctx;struct gl_context *shareCtx = share ? share->ctx : NULL;struct dd_function_table funcs;struct st_context *st;util_cpu_detect();memset(&funcs, 0, sizeof(funcs));st_init_driver_functions(pipe->screen, &funcs);// 省略 }

2.5 pipe_context

src/gallium/include/pipe/p_context.h

/*** Gallium rendering context. Basically:* - state setting functions* - VBO drawing functions* - surface functions*/ struct pipe_context {struct pipe_screen *screen;void *priv; /**< context private data (for DRI for example) */void *draw; /**< private, for draw module (temporary?) *//*** Stream uploaders created by the driver. All drivers, state trackers, and* modules should use them.** Use u_upload_alloc or u_upload_data as many times as you want.* Once you are done, use u_upload_unmap.*/struct u_upload_mgr *stream_uploader; /* everything but shader constants */struct u_upload_mgr *const_uploader; /* shader constants only */void (*destroy)( struct pipe_context * );

3 Interface

3.1 Device driver interfaces

src/mesa/main/mtypes.h

struct gl_context --> struct dd_function_table Driver

/*** Mesa rendering context.** This is the central context data structure for Mesa. Almost all* OpenGL state is contained in this structure.* Think of this as a base class from which device drivers will derive* sub classes.*/ struct gl_context { // 省略struct glthread_state *GLThread;struct gl_config Visual;struct gl_framebuffer *DrawBuffer; /**< buffer for writing */struct gl_framebuffer *ReadBuffer; /**< buffer for reading */struct gl_framebuffer *WinSysDrawBuffer; /**< set with MakeCurrent */struct gl_framebuffer *WinSysReadBuffer; /**< set with MakeCurrent *//*** Device driver function pointer table*/struct dd_function_table Driver; // 死亡凝視/** Core/Driver constants */struct gl_constants Const;/** \name The various 4x4 matrix stacks *//*@{*/struct gl_matrix_stack ModelviewMatrixStack;struct gl_matrix_stack ProjectionMatrixStack;struct gl_matrix_stack TextureMatrixStack[MAX_TEXTURE_UNITS];struct gl_matrix_stack ProgramMatrixStack[MAX_PROGRAM_MATRICES];struct gl_matrix_stack *CurrentStack; /**< Points to one of the above stacks */ // 省略 }

src/mesa/main/dd.h

/*** Device driver function table.* Core Mesa uses these function pointers to call into device drivers.* Most of these functions directly correspond to OpenGL state commands.* Core Mesa will call these functions after error checking has been done* so that the drivers don't have to worry about error testing.** Vertex transformation/clipping/lighting is patched into the T&L module.* Rasterization functions are patched into the swrast module.** Note: when new functions are added here, the drivers/common/driverfuncs.c* file should be updated too!!!*/ struct dd_function_table {/*** Return a string as needed by glGetString().* Only the GL_RENDERER query must be implemented. Otherwise, NULL can be* returned.*/const GLubyte * (*GetString)( struct gl_context *ctx, GLenum name );/*** Notify the driver after Mesa has made some internal state changes. ** This is in addition to any state change callbacks Mesa may already have* made.*/void (*UpdateState)(struct gl_context *ctx);/*** This is called whenever glFinish() is called.*/void (*Finish)( struct gl_context *ctx );/*** This is called whenever glFlush() is called.*/void (*Flush)( struct gl_context *ctx );/*** Clear the color/depth/stencil/accum buffer(s).* \param buffers a bitmask of BUFFER_BIT_* flags indicating which* renderbuffers need to be cleared.*/void (*Clear)( struct gl_context *ctx, GLbitfield buffers );/*** Execute glRasterPos, updating the ctx->Current.Raster fields*/void (*RasterPos)( struct gl_context *ctx, const GLfloat v[4] );// 省略 }

src/mesa/drivers/common/driverfuncs.h

#ifndef DRIVERFUNCS_H #define DRIVERFUNCS_H#ifdef __cplusplus extern "C" { #endifextern void _mesa_init_driver_functions(struct dd_function_table *driver);extern void _mesa_init_driver_state(struct gl_context *ctx);#ifdef __cplusplus } // extern "C" #endif#endif

src/mesa/drivers/common/driverfuncs.c

/*** Plug in default functions for all pointers in the dd_function_table* structure.* Device drivers should call this function and then plug in any* functions which it wants to override.* Some functions (pointers) MUST be implemented by all drivers (REQUIRED).** \param table the dd_function_table to initialize*/ void _mesa_init_driver_functions(struct dd_function_table *driver) {memset(driver, 0, sizeof(*driver));driver->GetString = NULL; /* REQUIRED! */driver->UpdateState = NULL; /* REQUIRED! */driver->Finish = NULL;driver->Flush = NULL; // 省略 }

src/mesa/state_tracker/st_cb_fbo.c

driver->ReadPixels = _mesa_readpixels;
_mesa_readpixels -> read_stencil_pixels -> ctx->Driver.MapRenderbuffer -> st_MapRenderbuffer

void st_init_fbo_functions(struct dd_function_table *functions) {functions->NewFramebuffer = _mesa_new_framebuffer;functions->NewRenderbuffer = st_new_renderbuffer;functions->FramebufferRenderbuffer = _mesa_FramebufferRenderbuffer_sw;functions->RenderTexture = st_render_texture;functions->FinishRenderTexture = st_finish_render_texture;functions->ValidateFramebuffer = st_validate_framebuffer;functions->DiscardFramebuffer = st_discard_framebuffer;functions->DrawBufferAllocate = st_DrawBufferAllocate;functions->ReadBuffer = st_ReadBuffer;functions->MapRenderbuffer = st_MapRenderbuffer;functions->UnmapRenderbuffer = st_UnmapRenderbuffer;functions->EvaluateDepthValues = st_EvaluateDepthValues; }/*** Called via* ctx->Driver.MapRenderbuffer.*/ static void st_MapRenderbuffer(struct gl_context *ctx,struct gl_renderbuffer *rb,GLuint x, GLuint y, GLuint w, GLuint h,GLbitfield mode,GLubyte **mapOut, GLint *rowStrideOut,bool flip_y) {struct st_context *st = st_context(ctx);struct st_renderbuffer *strb = st_renderbuffer(rb);struct pipe_context *pipe = st->pipe;const GLboolean invert = flip_y;GLuint y2;GLubyte *map;// 省略 }

總結

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