• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Martin Perry

OpenGL
Fragment shader variables count (iPhone4)

5 posts in this topic

I have high number of variables (30 uniforms (mostly vec4), about 20 variables (vec3, float, vec4) within shader) within fragment shader. It runs just fine on iPhone5S, but I have serious problem on iPhone4. GPU time is 1s / frame and 98% of the time is shader run time.

According to Apple API

 

OpenGL ES limits the number of each variable type you can use in a vertex or fragment shader. The OpenGL ES specification doesn’t require implementations to provide a software fallback when these limits are exceeded; instead, the shader simply fails to compile or link. When developing your app you must ensure that no errors occur during shader compilation, as shown in Listing 10-1.

 

 

 

But from this I quite dont understand. Do they provide SW fallback or not? Because I have no errors during compilation or linking of shader and yet performance is poor. I have comment almost everything out and just leave 2 texture lookups and directional light computation. I changed other functions to return just vec4(0,0,0,0).

Edited by Martin Perry
0

Share this post


Link to post
Share on other sites

But from this I quite dont understand. Do they provide SW fallback or not? Because I have no errors during compilation or linking of shader and yet performance is poor. I have comment almost everything out and just leave 2 texture lookups and directional light computation. I changed other functions to return just vec4(0,0,0,0).

I don’t believe they have a software fallback There is no software fallback on any iOS device, and your case essentially proves this isn’t the issue anyway.
The compiler will strip unused uniforms entirely; only uniforms that contribute to the output remain in any shaders. Even if you do access them, if they still don’t contribute to the output they are eliminated (as are local variables).

If you have removed enough to return hard-coded black mixed with a few texture reads, you have undoubtedly eliminated substantially enough uniforms and locals that you are nowhere near any device limits.
Your bottleneck should be elsewhere.


You should post the shaders before and after you reduce its complexity though to be sure this is the case.


L. Spiro Edited by L. Spiro
0

Share this post


Link to post
Share on other sites

I have about 30 shaders with high complexity (about 30+ uniforms for each of them). My render loop currently uses only one shader, that I reduced to bare minimum (you are right, uniforms are stripped away during build)

 

My current shader looks like this:


vec4 CalcAmbientLight(Material mat, float fIntensity)
{
    return mat.vAmbient * en_vAmbLightColor * fIntensity;
}

uniform sampler2D normal_buffer;
uniform sampler2D bg_buffer;

uniform vec2 canvasSize;

uniform SpotLight en_spotLight[6];

varying vec2 vTexCoord;

void main()
{			

  vec4 normalMap = texture2D(normal_buffer, vTexCoord); //normal_buffer is RGBA (GL_RGBA)
  vec3 bgColor = texture2D(bg_buffer, vTexCoord).rgb; //bg_buffer is RGB (GL_RGB)

    
  vec3 vNormal = normalize((2.0 * normalMap.rbg) - 1.0);

  vec3 posWS = vec3(vTexCoord.x * canvasSize.x, normalMap.a, vTexCoord.y * canvasSize.y);


  //----------------------------------------------------------------------------------
  Material mat;
  mat.vAmbient = vec4(bgColor, 1.0);
  mat.vDiffuse = vec4(bgColor, 1.0);
  mat.vSpecular = vec4(1.0);
  mat.fShiness = 30.0;
 

    vec4 vPhong = CalcAmbientLight(mat, 0.2);
    
  vPhong.a = 1.0;
   gl_FragColor = vPhong;
}

Vertex shader is simple pass-through. I am rendering fullscreen quad at resolution of the iPhone4 screen.

 

With this piece of "nothing" code, I have 45fps (I know it is debug mode, but still it is way to low from 60fps). Same code has 60fps on iPhone5S. CPU is at 4.4ms / frame. GPU takes 20.1ms

 

Here is also my sequnce of calls from XCode frame trace

//use render to texture for the whole scene
#0 glBindFramebuffer(GL_FRAMEBUFFER, 7)
#1 glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 6, 0)
#2 GL_FRAMEBUFFER_COMPLETE <- glCheckFramebufferStatus(GL_FRAMEBUFFER)
#3 glBindRenderbuffer(GL_RENDERBUFFER, 8)
#4 glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 8)
#5 GL_FRAMEBUFFER_COMPLETE <- glCheckFramebufferStatus(GL_FRAMEBUFFER)
#6 glUseProgram(17)
#7 glBindTexture(GL_TEXTURE_2D, 3)
#8 glBindVertexArray(1)
#9 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 44)
#10 glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr)
#11 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0)
#12 glBindVertexArray(0)
//----------------------------- End of main rendering --------
//now render texture to screen
#13 glBindFramebuffer(GL_FRAMEBUFFER, 1)
#14 glBindRenderbuffer(GL_RENDERBUFFER, 2)
#15 glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, 2)
#16 GL_FRAMEBUFFER_COMPLETE <- glCheckFramebufferStatus(GL_FRAMEBUFFER)
#17 glBindRenderbuffer(GL_RENDERBUFFER, 1)
#18 glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 1)
#19 GL_FRAMEBUFFER_COMPLETE <- glCheckFramebufferStatus(GL_FRAMEBUFFER)
#20 glUseProgram(25)
#21 glBindTexture(GL_TEXTURE_2D, 6)
#22 glBindVertexArray(2)
#23 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 4)
#24 glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, nullptr)
#25 glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0)
#26 glBindVertexArray(0)
#27 glDiscardFramebufferEXT(GL_FRAMEBUFFER, 1, {GL_DEPTH_ATTACHMENT})
#28 glBindRenderbuffer(GL_RENDERBUFFER, 2)
#29 ["Context 1" presentRenderbuffer:GL_RENDERBUFFER]


Edited by Martin Perry
0

Share this post


Link to post
Share on other sites

45 fps when rendering at full resolution on an iPhone4 might well be normal, even with a shader that simple. An iPhone4 GPU is only slightly superior to a 3GS GPU, but it has 4 times the number of pixels to fill, so it really struggles with fill rate.

 

Remember that vsync is always on, so your reported 45fps might in reality be 59fps getting rounded down due to vsync.

 

Also, adding logical buffer discard and clear commands can speed things up. At the start of your frame the first thing that OpenGL is doing there is copying the previous frames framebuffers onto the new framebuffer, because the driver has no way of telling that you don't want them.

 

edit: Oops, just spotted the discard command. I think a glClear would still help though probably.

Edited by C0lumbo
0

Share this post


Link to post
Share on other sites

 

But from this I quite dont understand. Do they provide SW fallback or not? Because I have no errors during compilation or linking of shader and yet performance is poor. I have comment almost everything out and just leave 2 texture lookups and directional light computation. I changed other functions to return just vec4(0,0,0,0).

I don’t believe they have a software fallback, and your case essentially proves this isn’t the issue anyway (at least at face value for now).
The compiler will strip unused uniforms entirely; only uniforms that contribute to the output remain in any shaders. Even if you do access them, if they still don’t contribute to the output they are eliminated (as are local variables).

If you have removed enough to return hard-coded black mixed with a few texture reads, you have undoubtedly eliminated substantially enough uniforms and locals that you are nowhere near any device limits.
Your bottleneck should be elsewhere.


You should post the shaders before and after you reduce its complexity though to be sure this is the case.


L. Spiro

 

 

There definelty is software fallback. I once hit that when I tried to support too many lights at vertex shader and peformance dropped to >400ms per frame. Then I reduced one light and frame time dropped to 10ms. Profiler clearly indicated that most of the time was spent at software shader pipeline.

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Similar Content

    • By Toastmastern
      So it's been a while since I took a break from my whole creating a planet in DX11. Last time around I got stuck on fixing a nice LOD.
      A week back or so I got help to find this:
      https://github.com/sp4cerat/Planet-LOD
      In general this is what I'm trying to recreate in DX11, he that made that planet LOD uses OpenGL but that is a minor issue and something I can solve. But I have a question regarding the code
      He gets the position using this row
      vec4d pos = b.var.vec4d["position"]; Which is then used further down when he sends the variable "center" into the drawing function:
      if (pos.len() < 1) pos.norm(); world::draw(vec3d(pos.x, pos.y, pos.z));  
      Inside the draw function this happens:
      draw_recursive(p3[0], p3[1], p3[2], center); Basically the 3 vertices of the triangle and the center of details that he sent as a parameter earlier: vec3d(pos.x, pos.y, pos.z)
      Now onto my real question, he does vec3d edge_center[3] = { (p1 + p2) / 2, (p2 + p3) / 2, (p3 + p1) / 2 }; to get the edge center of each edge, nothing weird there.
      But this is used later on with:
      vec3d d = center + edge_center[i]; edge_test[i] = d.len() > ratio_size; edge_test is then used to evaluate if there should be a triangle drawn or if it should be split up into 3 new triangles instead. Why is it working for him? shouldn't it be like center - edge_center or something like that? Why adding them togheter? I asume here that the center is the center of details for the LOD. the position of the camera if stood on the ground of the planet and not up int he air like it is now.

      Full code can be seen here:
      https://github.com/sp4cerat/Planet-LOD/blob/master/src.simple/Main.cpp
      If anyone would like to take a look and try to help me understand this code I would love this person. I'm running out of ideas on how to solve this in my own head, most likely twisted it one time to many up in my head
      Thanks in advance
      Toastmastern
       
       
    • By fllwr0491
      I googled around but are unable to find source code or details of implementation.
      What keywords should I search for this topic?
      Things I would like to know:
      A. How to ensure that partially covered pixels are rasterized?
         Apparently by expanding each triangle by 1 pixel or so, rasterization problem is almost solved.
         But it will result in an unindexable triangle list without tons of overlaps. Will it incur a large performance penalty?
      B. A-buffer like bitmask needs a read-modiry-write operation.
         How to ensure proper synchronizations in GLSL?
         GLSL seems to only allow int32 atomics on image.
      C. Is there some simple ways to estimate coverage on-the-fly?
         In case I am to draw 2D shapes onto an exisitng target:
         1. A multi-pass whatever-buffer seems overkill.
         2. Multisampling could cost a lot memory though all I need is better coverage.
            Besides, I have to blit twice, if draw target is not multisampled.
       
    • By mapra99
      Hello

      I am working on a recent project and I have been learning how to code in C# using OpenGL libraries for some graphics. I have achieved some quite interesting things using TAO Framework writing in Console Applications, creating a GLUT Window. But my problem now is that I need to incorporate the Graphics in a Windows Form so I can relate the objects that I render with some .NET Controls.

      To deal with this problem, I have seen in some forums that it's better to use OpenTK instead of TAO Framework, so I can use the glControl that OpenTK libraries offer. However, I haven't found complete articles, tutorials or source codes that help using the glControl or that may insert me into de OpenTK functions. Would somebody please share in this forum some links or files where I can find good documentation about this topic? Or may I use another library different of OpenTK?

      Thanks!
    • By Solid_Spy
      Hello, I have been working on SH Irradiance map rendering, and I have been using a GLSL pixel shader to render SH irradiance to 2D irradiance maps for my static objects. I already have it working with 9 3D textures so far for the first 9 SH functions.
      In my GLSL shader, I have to send in 9 SH Coefficient 3D Texures that use RGBA8 as a pixel format. RGB being used for the coefficients for red, green, and blue, and the A for checking if the voxel is in use (for the 3D texture solidification shader to prevent bleeding).
      My problem is, I want to knock this number of textures down to something like 4 or 5. Getting even lower would be a godsend. This is because I eventually plan on adding more SH Coefficient 3D Textures for other parts of the game map (such as inside rooms, as opposed to the outside), to circumvent irradiance probe bleeding between rooms separated by walls. I don't want to reach the 32 texture limit too soon. Also, I figure that it would be a LOT faster.
      Is there a way I could, say, store 2 sets of SH Coefficients for 2 SH functions inside a texture with RGBA16 pixels? If so, how would I extract them from inside GLSL? Let me know if you have any suggestions ^^.
    • By KarimIO
      EDIT: I thought this was restricted to Attribute-Created GL contexts, but it isn't, so I rewrote the post.
      Hey guys, whenever I call SwapBuffers(hDC), I get a crash, and I get a "Too many posts were made to a semaphore." from Windows as I call SwapBuffers. What could be the cause of this?
      Update: No crash occurs if I don't draw, just clear and swap.
      static PIXELFORMATDESCRIPTOR pfd = // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format 32, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 24, // 24Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC = GetDC(windowHandle))) return false; unsigned int PixelFormat; if (!(PixelFormat = ChoosePixelFormat(hDC, &pfd))) return false; if (!SetPixelFormat(hDC, PixelFormat, &pfd)) return false; hRC = wglCreateContext(hDC); if (!hRC) { std::cout << "wglCreateContext Failed!\n"; return false; } if (wglMakeCurrent(hDC, hRC) == NULL) { std::cout << "Make Context Current Second Failed!\n"; return false; } ... // OGL Buffer Initialization glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT); glBindVertexArray(vao); glUseProgram(myprogram); glDrawElements(GL_TRIANGLES, indexCount, GL_UNSIGNED_SHORT, (void *)indexStart); SwapBuffers(GetDC(window_handle));  
  • Popular Now