Re: [Mesa-dev] OSMesa Help
On 07/15/2013 05:38 PM, Andy Li wrote: Hi Brian, Thank you so much for your time and help along, up to this point, the code make much more sense to me. However, I have a few more questions here, hope that you will be able to help me out. I am wondering Where the aa_general_rgba_line() and aa_rgba_line() functions defined? In s_aaline.c, see: #define NAME(x) aa_rgba_##x #define DO_Z #include s_aalinetemp.h #define NAME(x) aa_general_rgba_##x #define DO_Z #define DO_ATTRIBS #include s_aalinetemp.h the NAME macro is used by the template code in the .h file to name the functions. When and where the functions in s_aalinetemp.h and s_aaline.c are called/used? Called via swrast-Line(). You could run an AA line test program in gdb, set a breakpoint on aa_rgba_line() and look at the stack trace. Are the draw_line, draw_triangle, draw_point functions in OSMesa some how connected with src/mesa/main/line.c or point.c? Not really. The later files just set state related to those prims. Is it possible to take out some required functions for example aa_rgba_line(), gl_context, etc. and compile it on my system so that I can draw a line into the framebuffer? (Or since there are too many functions linked together, you would not recommend me to do that?) I don't think that's feasible. -Brian ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
On 10/07/2013 3:20 PM, Andy Li wrote: Hello everyone, I have some questions regarding to OSMesa. I am currently working on a project which I have to use Mesa on an embedded system. My current goal is to port the base functions over to the embedded system, so that I can draw a line on a provided VGA screen. Since the embedded system I am using does not contain a GPU, therefore I have decided to use OSMesa for rendering process. I am wondering if there are any documentations/ specifications for OSMesa? Anyone know which are the base functions that OSMesa used for the rendering process? I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying to figure out how the code works, am I in the right direction? Moreover, for example, if I found a drawpix() function, how do I know if OSMesa actually used this function during rendering process? Is there any tool/debugger I can use to confirm my findings? Thank you for your time. Andy. See http://cgit.freedesktop.org/mesa/demos/tree/src/osdemos for example of using OSMesa. Regards, Jonathan ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
On 07/14/2013 09:34 PM, Andy Li wrote: Hi, I have some questions on the OSMesa code. As you suggested, I have continue looking into the swrast code. However, I have trouble figuring out how the code works exactly. Now I am now only focusing on the functions which draw lines. As I look into s_lines.c, I saw the _swrast_choose_line(). And depends on different cases, it will call _swrast_choose_aa_line_function(ctx) or USE(general_line) or USE(rgba_line) or USE(simple_no_z_rgba_line) etc. The first thing I did is looking into the _swrast_choose_aa_line_function() and it direct me to s_aaline.c In that file, I saw the struct of LineInfo and other computation functions for plane. Then I looked at the _swrast_choose_aa_line_function() and when I saw the code: swrast-Line = aa_general_rgba_line; and swrast-Line = aa_rgba_line; I am not sure what do they mean. And I won't be able to continue finding useful info. aa_rgba_line() drawns a simple RGBA antialiased line while aa_general_rgba_line() also computes texture coords, fog coord, etc. I think the main problem I am having is I am not sure what are the steps OSMesa have to take in order to draw a line into the frame buffer. Would you be able to explain a bit on that? (what are the steps OSMesa have to take in order to draw a line into the frame buffer?) Does drawing a line involve computing the plane? AA lines are drawn by drawing a quadrilateral and computing pixel coverage involves computing plane equations. What do s_aaline.c and s_aalinetemp.h actually mean? the temp files contain template code that's re-used multiple times in the .c file. What is USE(general_line) ? Where is USE() define? grep define USE src/mesa/swrast/*.[ch] What is swrast-Line = aa_general_rgba_line;? swrast-Line is a function pointer that points to the current line drawing function. The function is chosen by examining current GL rasterization state. Would you suggest any debugging tool for me so that I can trace which functions are called while the program is running? For example I have the code below: glBegin(GL_LINES); glVertex3f(0.0, 0.0, 0.0); glVertex3f(15, 0, 0); glEnd(); Is there any debugging tool which can trace glVertex3f back in the library and see how OSMesa works? I have tried using gdb, however, it would only by-pass the call the go to the next command. You'll need to build mesa for debugging (CFLAGS=-g -O0 --enable-debug). But I don't really have time to explain all the nuances of debugging/tracing in Mesa. I'm not sure that'd really help you anyway. In general, when you drawing points/lines/triangles the s_points.c or s_lines.c or s_triangle.c code winds up calling _swrast_write_rgba() span. This function does Z testing, texturing, stippling, etc before calling a put_pixels or put_row function. Those functions call a pack function to pack an array of RGBA ubyte/float values into the framebuffer. Packing involves converting a canonical RGBA format into a specific pixel format, like RGBA, or RGB565, etc. The color buffer address, stride, etc. is obtained earlier through a call to ctx-Driver.MapRenderbuffer(). In the case of OSMesa, the color buffer is ordinary malloc'd memory that the user allocated. -Brian ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
Hi Brian, Thank you so much for your time and help along, up to this point, the code make much more sense to me.However, I have a few more questions here, hope that you will be able to help me out. I am wondering Where the aa_general_rgba_line() and aa_rgba_line() functions defined?When and where the functions in s_aalinetemp.h and s_aaline.c are called/used?Are the draw_line, draw_triangle, draw_point functions in OSMesa some how connected with src/mesa/main/line.c or point.c?Is it possible to take out some required functions for example aa_rgba_line(), gl_context, etc. and compile it on my system so that I can draw a line into the framebuffer? (Or since there are too many functions linked together, you would not recommend me to do that?) Thanks Andy. Date: Mon, 15 Jul 2013 08:24:58 -0600 From: bri...@vmware.com To: lilap...@hotmail.com CC: mesa-dev@lists.freedesktop.org Subject: Re: [Mesa-dev] OSMesa Help On 07/14/2013 09:34 PM, Andy Li wrote: Hi, I have some questions on the OSMesa code. As you suggested, I have continue looking into the swrast code. However, I have trouble figuring out how the code works exactly. Now I am now only focusing on the functions which draw lines. As I look into s_lines.c, I saw the _swrast_choose_line(). And depends on different cases, it will call _swrast_choose_aa_line_function(ctx) or USE(general_line) or USE(rgba_line) or USE(simple_no_z_rgba_line) etc. The first thing I did is looking into the _swrast_choose_aa_line_function() and it direct me to s_aaline.c In that file, I saw the struct of LineInfo and other computation functions for plane. Then I looked at the _swrast_choose_aa_line_function() and when I saw the code: swrast-Line = aa_general_rgba_line; and swrast-Line = aa_rgba_line; I am not sure what do they mean. And I won't be able to continue finding useful info. aa_rgba_line() drawns a simple RGBA antialiased line while aa_general_rgba_line() also computes texture coords, fog coord, etc. I think the main problem I am having is I am not sure what are the steps OSMesa have to take in order to draw a line into the frame buffer. Would you be able to explain a bit on that? (what are the steps OSMesa have to take in order to draw a line into the frame buffer?) Does drawing a line involve computing the plane? AA lines are drawn by drawing a quadrilateral and computing pixel coverage involves computing plane equations. What do s_aaline.c and s_aalinetemp.h actually mean? the temp files contain template code that's re-used multiple times in the .c file. What is USE(general_line) ? Where is USE() define? grep define USE src/mesa/swrast/*.[ch] What is swrast-Line = aa_general_rgba_line;? swrast-Line is a function pointer that points to the current line drawing function. The function is chosen by examining current GL rasterization state. Would you suggest any debugging tool for me so that I can trace which functions are called while the program is running? For example I have the code below: glBegin(GL_LINES); glVertex3f(0.0, 0.0, 0.0); glVertex3f(15, 0, 0); glEnd(); Is there any debugging tool which can trace glVertex3f back in the library and see how OSMesa works? I have tried using gdb, however, it would only by-pass the call the go to the next command. You'll need to build mesa for debugging (CFLAGS=-g -O0 --enable-debug). But I don't really have time to explain all the nuances of debugging/tracing in Mesa. I'm not sure that'd really help you anyway. In general, when you drawing points/lines/triangles the s_points.c or s_lines.c or s_triangle.c code winds up calling _swrast_write_rgba() span. This function does Z testing, texturing, stippling, etc before calling a put_pixels or put_row function. Those functions call a pack function to pack an array of RGBA ubyte/float values into the framebuffer. Packing involves converting a canonical RGBA format into a specific pixel format, like RGBA, or RGB565, etc. The color buffer address, stride, etc. is obtained earlier through a call to ctx-Driver.MapRenderbuffer(). In the case of OSMesa, the color buffer is ordinary malloc'd memory that the user allocated. -Brian ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
Hi, I have some questions on the OSMesa code.As you suggested, I have continue looking into the swrast code.However, I have trouble figuring out how the code works exactly.Now I am now only focusing on the functions which draw lines.As I look into s_lines.c, I saw the _swrast_choose_line().And depends on different cases, it will call _swrast_choose_aa_line_function(ctx)or USE(general_line)orUSE(rgba_line)orUSE(simple_no_z_rgba_line)etc. The first thing I did is looking into the _swrast_choose_aa_line_function() and it direct me to s_aaline.cIn that file, I saw the struct of LineInfo and other computation functions for plane.Then I looked at the _swrast_choose_aa_line_function() and when I saw the code:swrast-Line = aa_general_rgba_line;andswrast-Line = aa_rgba_line; I am not sure what do they mean. And I won't be able to continue finding useful info. I think the main problem I am having is I am not sure what are the steps OSMesa have to take in order to draw a line into the frame buffer. Would you be able to explain a bit on that? ( what are the steps OSMesa have to take in order to draw a line into the frame buffer?)Does drawing a line involve computing the plane?What do s_aaline.c and s_aalinetemp.h actually mean? What is USE(general_line) ? Where is USE() define?What is swrast-Line = aa_general_rgba_line;?Would you suggest any debugging tool for me so that I can trace which functions are called while the program is running?For example I have the code below:glBegin(GL_LINES);glVertex3f(0.0, 0.0, 0.0); glVertex3f(15, 0, 0);glEnd();Is there any debugging tool which can trace glVertex3f back in the library and see how OSMesa works?I have tried using gdb, however, it would only by-pass the call the go to the next command. Thank you so much for your time. Andy. Date: Wed, 10 Jul 2013 12:53:19 -0600 From: bri...@vmware.com To: lilap...@hotmail.com; mesa-dev@lists.freedesktop.org Subject: Re: [Mesa-dev] OSMesa Help Please keep your replies on the list so that others can potentially help/reply. On 07/10/2013 12:05 PM, Andy Li wrote: Hi Brain, Thank you for your reply. You were right, my plan is to use OSMesa and draw into malloc'd frame buffer in my device, so I can display the image on the screen. For base functions, what i meant are the drawline() or drawpix() functions. In other words, I am wondering which are the functions OSMesa used to draw a line/pixel into the memory (changing the color/rgba value in frame buffer)? In the swrast code, look at s_lines.c, s_triangle.c, etc. to see how lines and triangles are drawn. In some (simple) cases we can write directly into the framebuffer but other times we call functions like _swrast_write_rgba_span() to do fragment processing/writing. To access the framebuffer's memory we use the ctx-Driver.Map/UnmapRenderbuffer() functions. Why am I trying to find these functions? The other part of my project is to rewrite these functions with an accelerator, so that I can speed up the rendering process with the embedded system I am using. Would you be able to give me some info/ suggestions on what I am doing? See above. Otherwise, just study the code for a while. It's not all that complicated. -Brian Thanks, Andy Date: Wed, 10 Jul 2013 07:49:09 -0600 From: bri...@vmware.com To: lilap...@hotmail.com CC: mesa-dev@lists.freedesktop.org Subject: Re: [Mesa-dev] OSMesa Help On 07/09/2013 11:20 PM, Andy Li wrote: Hello everyone, I have some questions regarding to OSMesa. I am currently working on a project which I have to use Mesa on an embedded system. My current goal is to port the base functions over to the embedded system, so that I can draw a line on a provided VGA screen. Since the embedded system I am using does not contain a GPU, therefore I have decided to use OSMesa for rendering process. I am wondering if there are any documentations/ specifications for OSMesa? End users of OSMesa generally get by on the comments in osmesa.h and the example programs. But you're working on the driver implementation side. Anyone know which are the base functions that OSMesa used for the rendering process? I don't know what you mean by base functions. In Mesa/master git, the OSMesa can either be used with the legacy swrast driver or with the gallium softpipe/llvmpipe drivers. I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying to figure out how the code works, am I in the right direction? That code is used by the legacy OSMesa driver, but it's also used by the old Xlib driver too. Moreover, for example, if I found a drawpix() function, how do I know if OSMesa actually used this function during rendering process? Is there any tool/debugger I
Re: [Mesa-dev] OSMesa Help
On 07/09/2013 11:20 PM, Andy Li wrote: Hello everyone, I have some questions regarding to OSMesa. I am currently working on a project which I have to use Mesa on an embedded system. My current goal is to port the base functions over to the embedded system, so that I can draw a line on a provided VGA screen. Since the embedded system I am using does not contain a GPU, therefore I have decided to use OSMesa for rendering process. I am wondering if there are any documentations/ specifications for OSMesa? End users of OSMesa generally get by on the comments in osmesa.h and the example programs. But you're working on the driver implementation side. Anyone know which are the base functions that OSMesa used for the rendering process? I don't know what you mean by base functions. In Mesa/master git, the OSMesa can either be used with the legacy swrast driver or with the gallium softpipe/llvmpipe drivers. I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying to figure out how the code works, am I in the right direction? That code is used by the legacy OSMesa driver, but it's also used by the old Xlib driver too. Moreover, for example, if I found a drawpix() function, how do I know if OSMesa actually used this function during rendering process? Is there any tool/debugger I can use to confirm my findings? One would normally set a breakpoint on the function in gdb or another debugger. Let's take a few steps back here first. You said you want to display graphics on your VGA screen. OSMesa will not do that for you. OS=Off-Screen. The whole point of OSMesa is to draw into malloc'd framebuffer memory, rather than drawing to a real/displayed framebuffer. You could use OSMesa and then do some sort of memcpy of the image into your devices's actual frame buffer. Is that what you want to do? -Brian ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
Please keep your replies on the list so that others can potentially help/reply. On 07/10/2013 12:05 PM, Andy Li wrote: Hi Brain, Thank you for your reply. You were right, my plan is to use OSMesa and draw into malloc'd frame buffer in my device, so I can display the image on the screen. For base functions, what i meant are the drawline() or drawpix() functions. In other words, I am wondering which are the functions OSMesa used to draw a line/pixel into the memory (changing the color/rgba value in frame buffer)? In the swrast code, look at s_lines.c, s_triangle.c, etc. to see how lines and triangles are drawn. In some (simple) cases we can write directly into the framebuffer but other times we call functions like _swrast_write_rgba_span() to do fragment processing/writing. To access the framebuffer's memory we use the ctx-Driver.Map/UnmapRenderbuffer() functions. Why am I trying to find these functions? The other part of my project is to rewrite these functions with an accelerator, so that I can speed up the rendering process with the embedded system I am using. Would you be able to give me some info/ suggestions on what I am doing? See above. Otherwise, just study the code for a while. It's not all that complicated. -Brian Thanks, Andy Date: Wed, 10 Jul 2013 07:49:09 -0600 From: bri...@vmware.com To: lilap...@hotmail.com CC: mesa-dev@lists.freedesktop.org Subject: Re: [Mesa-dev] OSMesa Help On 07/09/2013 11:20 PM, Andy Li wrote: Hello everyone, I have some questions regarding to OSMesa. I am currently working on a project which I have to use Mesa on an embedded system. My current goal is to port the base functions over to the embedded system, so that I can draw a line on a provided VGA screen. Since the embedded system I am using does not contain a GPU, therefore I have decided to use OSMesa for rendering process. I am wondering if there are any documentations/ specifications for OSMesa? End users of OSMesa generally get by on the comments in osmesa.h and the example programs. But you're working on the driver implementation side. Anyone know which are the base functions that OSMesa used for the rendering process? I don't know what you mean by base functions. In Mesa/master git, the OSMesa can either be used with the legacy swrast driver or with the gallium softpipe/llvmpipe drivers. I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying to figure out how the code works, am I in the right direction? That code is used by the legacy OSMesa driver, but it's also used by the old Xlib driver too. Moreover, for example, if I found a drawpix() function, how do I know if OSMesa actually used this function during rendering process? Is there any tool/debugger I can use to confirm my findings? One would normally set a breakpoint on the function in gdb or another debugger. Let's take a few steps back here first. You said you want to display graphics on your VGA screen. OSMesa will not do that for you. OS=Off-Screen. The whole point of OSMesa is to draw into malloc'd framebuffer memory, rather than drawing to a real/displayed framebuffer. You could use OSMesa and then do some sort of memcpy of the image into your devices's actual frame buffer. Is that what you want to do? -Brian ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
Re: [Mesa-dev] OSMesa Help
On Tue, Jul 9, 2013 at 10:20 PM, Andy Li lilap...@hotmail.com wrote: Hello everyone, I have some questions regarding to OSMesa. I am currently working on a project which I have to use Mesa on an embedded system. My current goal is to port the base functions over to the embedded system, so that I can draw a line on a provided VGA screen. Since the embedded system I am using does not contain a GPU, therefore I have decided to use OSMesa for rendering process. I am wondering if there are any documentations/ specifications for OSMesa? Anyone know which are the base functions that OSMesa used for the rendering process? I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying to figure out how the code works, am I in the right direction? Moreover, for example, if I found a drawpix() function, how do I know if OSMesa actually used this function during rendering process? Is there any tool/debugger I can use to confirm my findings? I suspect simply using one of the software drivers would be better. Maybe you'll want to run this program on a real GPU some day, and then it will run unmodified. ___ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
