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TTT_Dutch

OpenGL
glGenBuffers was not declared in this scope

31 posts in this topic

Well I am trying to learn Vertex Arrays and VBOs. I didn't really want to learn VAs but I tried them anyway and couldnt draw anything. I think that because its deprecated. But then I tried VBOS and I am trying to use the GenBuffer,BindBuffer, etc. for using VBOS and it gives me these errors:
glGenBuffers not declared in this scope
GL_ARRAY_BUFFER not declared in this scope
glBindBuffer not declared in this scope
GL_DYNAMIC_DRAW not declared in this scope
glBufferData not declared in this scope

I am using opengl 3.3 and I have included gl.h and glu.h and windows.h.

I only have probelms with these functions..
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You need the extensions. Google glew (glew.sourceforge.net). I think thats the address still. Everything in openGL is extended. gl.h is the original standard, every addition such as VBO's are separate for compatability.
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[quote name='dpadam450' timestamp='1296928598' post='4770061']
You need the extensions. Google glew (glew.sourceforge.net). I think thats the address still. Everything in openGL is extended. gl.h is the original standard, every addition such as VBO's are separate for compatability.
[/quote]

Thanks! Now I have another problem though. I downloaded glew but now I am getting this error:
error: cannot convert 'GLfloat' to 'const GLvoid*' in argument passing

on this function: glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*3, vbodat[0], GL_DYNAMIC_DRAW);
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[quote name='dpadam450' timestamp='1296929868' post='4770072']
vbdat[0] is a float, you want to pass the address of your data ........., &(vbodat[0])
[/quote]

Oh thanks! But now I am getting this:
|undefined reference to `_imp____glewGenBuffers'
same error for bindbuffer and bufferdata.
I have the lib in lib directory of codeblocks.
I linked the lib like this in other linker options: -lglew32
I have the dll in the folder too...
I have also tried linking it with link libs and found the file directly..
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I'm just using glew32.lib, dont know if they changed the name. You need to make sure it knows that path, otherwise just copy the whole filepath (+ .lib) and see if that works.
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[quote name='dpadam450' timestamp='1296931137' post='4770082']
I'm just using glew32.lib, dont know if they changed the name. You need to make sure it knows that path, otherwise just copy the whole filepath (+ .lib) and see if that works.
[/quote]

Ya I have a glew32.lib and a glew32s.lib for static.. I dont know why it isnt linking.
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[quote name='dpadam450' timestamp='1296936648' post='4770120']
glewGenBuffers its just glGenBuffers
[/quote]

Ya I know, I think I am just linking wrong or their is something wrong with my code. How do u link it?
I have the dll's and the libs... Dont I just need to have the dll and the header included to use this? Can I avoid libs?
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I use visual studio and just have the exact file path in the linker box. Try commenting out your glew related code, and see if you get an error that it cant find glew32.lib.
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[quote name='dpadam450' timestamp='1296937967' post='4770129']
I use visual studio and just have the exact file path in the linker box. Try commenting out your glew related code, and see if you get an error that it cant find glew32.lib.
[/quote]

Well I got it working partly working statically but not dynamically. I can build the project but can execute it.

EDIT: It just stopped working.. Any tutorials for codeblocks you know of?
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Hi TTT_Dutch,

you dont need glew for using glGenBuffers,

just do the following:

before including SDL, glut or whatever window handling system you use type the following line:

#define GL_GLEXT_PROTOTYPES

voila, you should be able to use it.

for some functions like glGenRenderbuffers() you need to use the following instead:

glGenRenderbuffers[b]EXT[/b]()

Hope I could help,
Yours3!f
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[quote name='Yours3!f' timestamp='1296938986' post='4770136']
Hi TTT_Dutch,

you dont need glew for using glGenBuffers,

just do the following:

before including SDL, glut or whatever window handling system you use type the following line:

#define GL_GLEXT_PROTOTYPES

voila, you should be able to use it.

for some functions like glGenRenderbuffers() you need to use the following instead:

glGenRenderbuffers[b]EXT[/b]()

Hope I could help,
Yours3!f
[/quote]

Thats not working.. I still get the original errors.
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Now I know its my code because I commented out all the glew functions and the program ran. Unless calling the lib makes it crash...

It seems like anything that is called form glew makes the program crash or not start. So...

EDIT: tried wglew and got wierd errors. Then I moved it below gl included files and I got original errors.
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[quote name='TTT_Dutch' timestamp='1296942669' post='4770155']
Now I know its my code because I commented out all the glew functions and the program ran. Unless calling the lib makes it crash...

It seems like anything that is called form glew makes the program crash or not start. So...

EDIT: tried wglew and got wierd errors. Then I moved it below gl included files and I got original errors.
[/quote]


Are you calling glewInit() after you have created your OpenGL context? and is it successful?
If you aren't doing this read the 'Initializing GLEW' section on this page [url="http://glew.sourceforge.net/basic.html"]GLEW basics[/url]
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[quote name='_Unicron_' timestamp='1296943720' post='4770159']
[quote name='TTT_Dutch' timestamp='1296942669' post='4770155']
Now I know its my code because I commented out all the glew functions and the program ran. Unless calling the lib makes it crash...

It seems like anything that is called form glew makes the program crash or not start. So...

EDIT: tried wglew and got wierd errors. Then I moved it below gl included files and I got original errors.
[/quote]


Are you calling glewInit() after you have created your OpenGL context? and is it successful?
If you aren't doing this read the 'Initializing GLEW' section on this page [url="http://glew.sourceforge.net/basic.html"]GLEW basics[/url]
[/quote]

Thanks! I feel so dumb! Still cant get it working dynamically though.. But now I cant get the vbo's working... I use them like this



[code]
GLuint vbo;
GLfloat vbodat[12] =
{0,0,20,
0,20,20,
20,20,20,
20,0,20};

glEnableClientState(GL_VERTEX_ARRAY);
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*3, &vbodat[0], GL_DYNAMIC_DRAW);[/code]


Then in the loop

[code]glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT, 0, BUFFER_OFFSET(0));
glDrawArrays(GL_QUADS, 0, 3);
glDisableClientState(GL_VERTEX_ARRAY);[/code]
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When you are linking against the dynamic libs make sure you don't use #define GLEW_STATIC 1 anywhere. You may not have commented it out or something.The second parameter of glBufferData is the size of the data to upload in bytes. The second parameter should be sizeof(GLfloat) * 12.
Also the params for glDrawArrays should be (GL_QUADS, 0, 4)
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[quote name='_Unicron_' timestamp='1296949288' post='4770182']
When you are linking against the dynamic libs make sure you don't use #define GLEW_STATIC 1 anywhere. You may not have commented it out or something.The second parameter of glBufferData is the size of the data to upload in bytes. The second parameter should be sizeof(GLfloat) * 12.
Also the params for glDrawArrays should be (GL_QUADS, 0, 4)
[/quote]

The GL_quad adjustmnet causes crash. BTW the dynamic this still doesnt work. All I do is link it and nothing..
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[quote name='TTT_Dutch' timestamp='1296950720' post='4770199']
[quote name='_Unicron_' timestamp='1296949288' post='4770182']
When you are linking against the dynamic libs make sure you don't use #define GLEW_STATIC 1 anywhere. You may not have commented it out or something.The second parameter of glBufferData is the size of the data to upload in bytes. The second parameter should be sizeof(GLfloat) * 12.
Also the params for glDrawArrays should be (GL_QUADS, 0, 4)
[/quote]

The GL_quad adjustmnet causes crash. BTW the dynamic this still doesnt work. All I do is link it and nothing..
[/quote]

OK, let's not worry about the dynamic linking for the moment (one problem at a time). You should have something like this now:

[code]
GLuint vbo;
GLfloat vbodat[12] = { 0.0f, 0.0f, 20.0f,
0.0f, 20.0f, 20.0f,
20.0f, 20.0f, 20.0f,
20.0f, 0.0f, 20.0f};

glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*12, &vbodat[0], GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

Now make sure you bind the VBO when you do your drawing:

[code]
glBindBuffer(GL_ARRAY_BUFFER, vbo);

glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT, 0, 0);
glDrawArrays(GL_QUADS, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

If you get any errors with this, post the error messages.
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[quote name='_Unicron_' timestamp='1296997709' post='4770388']
[quote name='TTT_Dutch' timestamp='1296950720' post='4770199']
[quote name='_Unicron_' timestamp='1296949288' post='4770182']
When you are linking against the dynamic libs make sure you don't use #define GLEW_STATIC 1 anywhere. You may not have commented it out or something.The second parameter of glBufferData is the size of the data to upload in bytes. The second parameter should be sizeof(GLfloat) * 12.
Also the params for glDrawArrays should be (GL_QUADS, 0, 4)
[/quote]

The GL_quad adjustmnet causes crash. BTW the dynamic this still doesnt work. All I do is link it and nothing..
[/quote]

OK, let's not worry about the dynamic linking for the moment (one problem at a time). You should have something like this now:

[code]
GLuint vbo;
GLfloat vbodat[12] = { 0.0f, 0.0f, 20.0f,
0.0f, 20.0f, 20.0f,
20.0f, 20.0f, 20.0f,
20.0f, 0.0f, 20.0f};

glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*12, &vbodat[0], GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

Now make sure you bind the VBO when you do your drawing:

[code]
glBindBuffer(GL_ARRAY_BUFFER, vbo);

glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT, 0, 0);
glDrawArrays(GL_QUADS, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

If you get any errors with this, post the error messages.
[/quote]

Sorry if I intervene, but if he is learning it now, he should learn it the proper way, meaning 3.x.
[url="http://www.arcsynthesis.org/gltut/"]Look here: Learning Modern 3D Graphics Programming Through OpenGL[/url]
GL_QUADS is depreacted, the same is for glEnable/glDisableClientState().

Really, look that tutorial and learn it from there. Learn it proper now and be prepared for the next years.
No offense though :)
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[quote name='NicoG' timestamp='1297002957' post='4770410']
[quote name='_Unicron_' timestamp='1296997709' post='4770388']
[quote name='TTT_Dutch' timestamp='1296950720' post='4770199']
[quote name='_Unicron_' timestamp='1296949288' post='4770182']
When you are linking against the dynamic libs make sure you don't use #define GLEW_STATIC 1 anywhere. You may not have commented it out or something.The second parameter of glBufferData is the size of the data to upload in bytes. The second parameter should be sizeof(GLfloat) * 12.
Also the params for glDrawArrays should be (GL_QUADS, 0, 4)
[/quote]

The GL_quad adjustmnet causes crash. BTW the dynamic this still doesnt work. All I do is link it and nothing..
[/quote]

OK, let's not worry about the dynamic linking for the moment (one problem at a time). You should have something like this now:

[code]
GLuint vbo;
GLfloat vbodat[12] = { 0.0f, 0.0f, 20.0f,
0.0f, 20.0f, 20.0f,
20.0f, 20.0f, 20.0f,
20.0f, 0.0f, 20.0f};

glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*12, &vbodat[0], GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

Now make sure you bind the VBO when you do your drawing:

[code]
glBindBuffer(GL_ARRAY_BUFFER, vbo);

glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3,GL_FLOAT, 0, 0);
glDrawArrays(GL_QUADS, 0, 4);
glDisableClientState(GL_VERTEX_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, NULL);
[/code]

If you get any errors with this, post the error messages.
[/quote]

Sorry if I intervene, but if he is learning it now, he should learn it the proper way, meaning 3.x.
[url="http://www.arcsynthesis.org/gltut/"]Look here: Learning Modern 3D Graphics Programming Through OpenGL[/url]
GL_QUADS is depreacted, the same is for glEnable/glDisableClientState().

Really, look that tutorial and learn it from there. Learn it proper now and be prepared for the next years.
No offense though :)
[/quote]

Oh so I should be learning new stuff? Any books that cover 3.3 and above?
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Dunno about Books atm, looking for some too. But I suggest you learn from 3.3. It is the best way. No sense in learning deprecated stuff now and then you need to forget what you have learned and relearn everything... the Tutorial I showed you is a good start.
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Eh, hes a beginner, he doesnt need an opengl 4.0 context. I have a 4.0GL card and my context is still 2.1. Learning graphics is still learning graphics.
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[quote name='dpadam450' timestamp='1297033884' post='4770668']
Eh, hes a beginner, he doesnt need an opengl 4.0 context. I have a 4.0GL card and my context is still 2.1. Learning graphics is still learning graphics.
[/quote]
Esp. as beginner you should use a 3.x context. It is not very much difference to 4.x from what I have read. But 2.x and 3.x is a difference like day and night.
And since I am currently in the middle of learning it, while I have learned my first steps with Nehe, I say, forget everything below 3.0.
It is a complete new level of thinking. It works different. And once you understood it, it is way more convinient as fixed functions.
Now you learned something like glOrtho and glPushMatrix, glPopMatrix. You can draw GL_QUADS etc. And then you decide to go to 3.x and you notice that all that is deprecated and unusable on 3.x. Knowledge obtained for nothing. Waste of time if you ask me.
Yes it helps if you need bullet-proof fallback code. But still...
But as always, this is just my personal opinion. B)


@TTT_Dutch
Forgot to mention OpenGL Superbible 5 as Book. It actually has 3.x. Planning to buy it, but hard to get it here in Germany without CC.
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      For this goal, the MyShapes class will be responsible for defining shapes such as triangles, polygons etc. Currently, there is only a drawTriangle() method implemented, because I first wanted to see whether it works or not before attempting to code other shape drawing methods.
      The constructor of the MyEngine class creates a GLFW window (GLAD is also initialized here to load all OpenGL functionality), and the myEngine.run() method in Main.cpp is responsible for firing up the engine. In this run() method, the shaders get loaded from files via the help of my FileHandler class. The vertices for the triangle are processed by the myShapes.drawTriangle() method where a vertex array object, a vertex buffer object and vertrex attributes are set for this purpose.
      The while loop in the run() method should be outputting me the desired red triangle, but all I get is a grey window area. Why?
      Note: The shaders are compiling and linking without any errors.
      (Note: I am aware that this code is not using any good software engineering practices (e.g. exceptions, error handling). I am planning to implement them later, once I get the hang of OpenGL.)

       
    • 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));  
    • By Tchom
      Hey devs!
       
      I've been working on a OpenGL ES 2.0 android engine and I have begun implementing some simple (point) lighting. I had something fairly simple working, so I tried to get fancy and added color-tinting light. And it works great... with only one or two lights. Any more than that, the application drops about 15 frames per light added (my ideal is at least 4 or 5). I know implementing lighting is expensive, I just didn't think it was that expensive. I'm fairly new to the world of OpenGL and GLSL, so there is a good chance I've written some crappy shader code. If anyone had any feedback or tips on how I can optimize this code, please let me know.
       
      Vertex Shader
      uniform mat4 u_MVPMatrix; uniform mat4 u_MVMatrix; attribute vec4 a_Position; attribute vec3 a_Normal; attribute vec2 a_TexCoordinate; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { v_Position = vec3(u_MVMatrix * a_Position); v_TexCoordinate = a_TexCoordinate; v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0)); gl_Position = u_MVPMatrix * a_Position; } Fragment Shader
      precision mediump float; uniform vec4 u_LightPos["+numLights+"]; uniform vec4 u_LightColours["+numLights+"]; uniform float u_LightPower["+numLights+"]; uniform sampler2D u_Texture; varying vec3 v_Position; varying vec3 v_Normal; varying vec2 v_TexCoordinate; void main() { gl_FragColor = (texture2D(u_Texture, v_TexCoordinate)); float diffuse = 0.0; vec4 colourSum = vec4(1.0); for (int i = 0; i < "+numLights+"; i++) { vec3 toPointLight = vec3(u_LightPos[i]); float distance = length(toPointLight - v_Position); vec3 lightVector = normalize(toPointLight - v_Position); float diffuseDiff = 0.0; // The diffuse difference contributed from current light diffuseDiff = max(dot(v_Normal, lightVector), 0.0); diffuseDiff = diffuseDiff * (1.0 / (1.0 + ((1.0-u_LightPower[i])* distance * distance))); //Determine attenuatio diffuse += diffuseDiff; gl_FragColor.rgb *= vec3(1.0) / ((vec3(1.0) + ((vec3(1.0) - vec3(u_LightColours[i]))*diffuseDiff))); //The expensive part } diffuse += 0.1; //Add ambient light gl_FragColor.rgb *= diffuse; } Am I making any rookie mistakes? Or am I just being unrealistic about what I can do? Thanks in advance
    • By yahiko00
      Hi,
      Not sure to post at the right place, if not, please forgive me...
      For a game project I am working on, I would like to implement a 2D starfield as a background.
      I do not want to deal with static tiles, since I plan to slowly animate the starfield. So, I am trying to figure out how to generate a random starfield for the entire map.
      I feel that using a uniform distribution for the stars will not do the trick. Instead I would like something similar to the screenshot below, taken from the game Star Wars: Empire At War (all credits to Lucasfilm, Disney, and so on...).

      Is there someone who could have an idea of a distribution which could result in such a starfield?
      Any insight would be appreciated
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