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?????????

OpenGL
[SOLVED] Generic Vertex Attribute

9 posts in this topic

[size="2"]
[size="2"]EDIT: Problem partially resolved, see post #8.[/size]
Hello,[/size]
[size="2"]I'm beginning OpenGL 4.2 in C# using the OpenTK binding (I'm aware that OpenTK binds only up to 3.2, so they have deprecated stuff available so I'm not using those functions, ya know... forward compatibility [img]http://public.gamedev.net/public/style_emoticons/default/cool.gif[/img]). Anyways, so I have got this basic pass-through vertex shader: (also embedded in program below)[/size]
[size="2"][source lang="c"][/size]
[size="2"]#version 410[/size]
[size="2"]#pragma debug(on)[/size]

[size="2"]uniform mat4 projection;[/size]
[size="2"]uniform mat4 view;[/size]

[size="2"]vec3 inVertexPos;[/size]

[size="2"]void main()[/size]
[size="2"]{[/size]
[size="2"] gl_Position = vec4(inVertexPos, 1.0) * projection * view;[/size]
[size="2"]}[/size]
[size="2"][/source][/size]
[size="2"]The problem I am having is marked on line 48 (generic vertex attribute location equals -1) below.[/size]

[size="2"]I can't seem to understand the reason for the error (as OpenGL does not really throw an error...), [/size][s]the OpenGL reference suggets it has to do with maximum generic vertex attribs; ....but it clearly doesn't.[/s]
[size="2"]Anyone can shed some light on the problem? I'll be most thankful.[/size]
[size="2"](The entire code-file is attached as a file to the post as well)[/size]
[size="2"]The main program (this is a class constructor, after this function returns the main loop runs calling the render function below):[/size]

[size="2"][source lang="csharp"][/size]
[size="2"]Matrix4 Projection;[/size]
[size="2"]Matrix4 View;
[/size]
int[] ShaderIDs;
int[] ProgramIDs;
uint[] VAOs;
uint[] VBOs;[font="arial, verdana, tahoma, sans-serif"][size="2"]
[size="2"]ushort[] Indices; // Cube indices[/size]
[size="2"]Vector3[] Vertices; // Cube vertices[/size]

[size="2"]public GameCtor()[/size]
[size="2"]{[/size]
[font="arial, verdana, tahoma, sans-serif"][size="2"] [/size][/font][size="2"]// Our uniform matrices[/size]
[font="arial, verdana, tahoma, sans-serif"][size="2"] [/size][/font][size="2"]Projection = Matrix4.CreatePerspectiveOffCenter(-Width / 2, Width / 2, -Height / 2, Height / 2, 0.01f, 500); // Perspective with 0,0 in the center and same as window width and height[/size]
[font="arial, verdana, tahoma, sans-serif"][size="2"] [/size][/font][size="2"]View = Matrix4.LookAt(0, 0, -100, 0, 0, 0, 0, 1, 0); // camera at (z = -100) looking at 0,0,0

[/size][/size][/font][font="arial, verdana, tahoma, sans-serif"][size="2"]
VAOs = new uint[1];
VBOs = new uint[2];
ShaderIDs = new int[2]; // Reserve space for 2 shaders, here we use one vertex shader
ProgramIDs = new int[1]; // Our shader program[/size][/font]
[font="arial, verdana, tahoma, sans-serif"][size="2"]
GL.GenVertexArrays(VAOs.Length, VAOs);[/size][/font]
GL.GenBuffers(VBOs.Length, VBOs);
InitVAOsVBOs();
InitVertexShader(); // Initialize our vertex shader

// Create a program and attach our first shader
ProgramIDs[0] = GL.CreateProgram();
GL.AttachShader(ProgramIDs[0], ShaderIDs[0]);

// Link and print result log
GL.LinkProgram(ProgramIDs[0]);
Console.WriteLine(GL.GetProgramInfoLog(ProgramIDs[0]));

// Start using our shader program
// Required before setting Uniforms,
// otherwise I get an error: InvalidValue
GL.UseProgram(ProgramIDs[0]);

// Set uniform projection and view matrices
int uProjIndex = GL.GetUniformLocation(ProgramIDs[0], "projection");
int uViewIndex = GL.GetUniformLocation(ProgramIDs[0], "view");
GL.UniformMatrix4(uProjIndex, true, ref Projection);
GL.UniformMatrix4(uViewIndex, true, ref View);

// Vertex Position attribute: vec3 inVertexPos;
int inVertexPosIndex = GL.GetAttribLocation(ProgramIDs[0], "inVertexPos"); // returns -1
GL.BindVertexArray(VAOs[0]);
GL.VertexAttribPointer(inVertexPosIndex, 3, VertexAttribPointerType.Float, false, 0, IntPtr.Zero);
GL.EnableVertexAttribArray(inVertexPosIndex);}
[/source]
Buffer initialization:
[source lang="csharp"]

private void InitVAOsVBOs()
{
Vertices = new Vector3[8] {
new Vector3(-80, 80, -80), //0 Top, Left, Front
new Vector3(-80, 80, 80), //1 Top, Left, Back
new Vector3(-80, -80, -80), //2 Top, Right, Front
new Vector3(-80, -80, 80), //3 Top, Right, Back
new Vector3( 80, 80, 80), //4 Bottom, Left, Front
new Vector3( 80, 80, -80), //5 Bottom, Left, Back
new Vector3( 80, -80, -80), //6 Bottom, Right, Front
new Vector3( 80, -80, 80) //7 Bottom, Right, Back
};
GL.BindBuffer(BufferTarget.ArrayBuffer, VBOs[0]);
GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Vertices.Length * Vector3.SizeInBytes), Vertices, BufferUsageHint.StaticDraw);
GL.BindVertexArray(VAOs[0]);

Indices = new ushort[24] {
0, 1, 3, 2, // Top face
0, 1, 5, 4, // Left face
1, 3, 7, 5, // Back face
2, 3, 7, 6, // Right face
4, 5, 7, 6, // Bottom face
0, 2, 6, 4 // Front face
};
GL.BindBuffer(BufferTarget.ElementArrayBuffer, VBOs[0]);
GL.BufferData(BufferTarget.ElementArrayBuffer, (IntPtr)(Indices.Length * sizeof(ushort)), Indices, BufferUsageHint.StaticDraw);
}[/source]
Vertex Shader initialization:
[source lang="csharp"]
private void InitVertexShader()
{
string VertexShaderSource = // Yes, this is inline shader source
@"#version 410
#pragma debug(on)

uniform mat4 projection;
uniform mat4 view;

vec3 inVertexPos;

void main()
{
gl_Position = vec4(inVertexPos, 1.0) * projection * view;
}";
// Create our vertex shader, upload our source, and compile
ShaderIDs[0] = GL.CreateShader(ShaderType.VertexShader);
GL.ShaderSource(ShaderIDs[0], VertexShaderSource);
GL.CompileShader(ShaderIDs[0]);
Console.WriteLine(GL.GetShaderInfoLog(ShaderIDs[0])); // check the log to make sure it succeeds
}
[/source]
Render code:
[source lang="csharp"]
protected override void OnRenderFrame(FrameEventArgs e)
{
GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

// Draw using the indices buffer
GL.DrawElements(BeginMode.Quads, Indices.Length, DrawElementsType.UnsignedShort, 0);

this.SwapBuffers();
}
[/source]
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Have you verified that inVertexPosIndex returns something other than -1? If you get that and pass it to AttribPointer it will probably fail.

I think you're missing the "in" keyword in your shader for this variable (unless this was removed in a more recent version than I'm familiar with).

"vec3 inVertexPos;"
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[s]yes, I checked that the location returned for the variable is always 1.
the 4.1 reference sheet says that if the "in" is omitted then it is implied.[/s]
[s]
[/s]
EDIT: The location returned is -1.
EDIT2: Fixed by adding the in keyword, as the OpenTK binding does not support higher than 1.5 GLSL. Edited by wiz3kid
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[quote name='V-man' timestamp='1313942898' post='4851929']
Do you have a VAO bound?
[/quote]
[s]See the InitBuffers() function. AFAIK, VAOs are deprecated since 3.3... and are removed since 4.0. VBO's are the way to go.[/s]
[s]
[/s]
EDIT: Now I do. [img]http://public.gamedev.net/public/style_emoticons/default/smile.gif[/img] Edited by wiz3kid
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VAO is in glspec33.core.20100311.pdf
glspec40.core.20100311.pdf
glspec41.core.20100725.pdf

You are forced to use them.
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[quote name='V-man' timestamp='1313967242' post='4852038']
VAO is in glspec33.core.20100311.pdf
glspec40.core.20100311.pdf
glspec41.core.20100725.pdf

You are forced to use them.
[/quote]

[s]Oh, I thought VAOs were the gl*Pointer family of functions....
So, I'm supposed to use glGenVertexArrays() instead of glGenBuffers()?[/s]

EDIT: Read up on it a bit, and I don't understand where the VAO gets its data from. I understood that I have to use both buffers and VAOs to achieve what I want , right? Edited by wiz3kid
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Problem partially resolved! No errors anymore, using gDEBugger I see that it's rendering 24 vertices each frame.
Now the next problem, I don't see anything on the screen. New code attached below.
I added a fragment shader which sets all the fragments to white color.
I've also attached a zip containing a binary for anyone interested.

[attachment=5009:Game1 - Copy.cs.txt]

[attachment=5010:ShadersAndPrograms.zip]
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I think
"gl_Position = vec4(inVertexPos, 1.0) * projection * view;"

should be
"gl_Position = projection * view * vec4(inVertexPos, 1.0);"

As you want to apply the view matrix to transform the vertex position into eye space,
and then project it into clipping space by multiplying with the projection matrix.
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[quote name='FlorianR' timestamp='1314007725' post='4852208']
I think
"gl_Position = vec4(inVertexPos, 1.0) * projection * view;"

should be
"gl_Position = projection * view * vec4(inVertexPos, 1.0);"

As you want to apply the view matrix to transform the vertex position into eye space,
and then project it into clipping space by multiplying with the projection matrix.
[/quote]


Still not working....
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