Problem withgeomtry shader and core 150

OpenGL
1

hi

my geomtry shader dosent work in core 150. my OpenGL version is 3.3

vertex shader code


#version 150 core
in vec3 in_Position;
uniform mat4 in_ModelViewMatrix;
in vec4 in_VertexColor;
out vec4 VertexColor;
void main(void)
{
VertexColor = in_VertexColor;
gl_Position = in_ModelViewMatrix * vec4(in_Position,1.0);
}

geomtry shader:


#version 150
#extension GL_EXT_geometry_shader4 : enable

void main(void)
{
	//increment variable
	int i;

	//Pass-thru!
	for(i=0; i< gl_VerticesIn; i++){
		gl_Position = gl_PositionIn[i];
		EmitVertex();
	}
	EndPrimitive();	
}

fragment shader:


#version 150 core
in vec4 VertexColor;
out vec4 out_Color;
void main(void)
{
   out_Color = vec4(0);
}

what is wrong?

2

How doesn’t it work?

3

any thing doesn’t show in screen but it compile successfully

4

Your fragment shader is outputting solid black with an alpha of zero (vec4(0)). Is your background also black?

Regards,
Patrick

5

I’d say you’d want to make two changes to make it work.

  1. declare a layout of the type and maximum quantity your geometry shader should output. e.g.:
    layout(triangle, max_vertices = 3) out;

  2. Instead of glPositionIn[i], you want to use gl_in[i].glPosition

I have a tutorial for geometry shaders at http://www.opengl.org/wiki/Tutorial4:_Using_Indices_and_Geometry_Shaders_(C_/SDL) that may be of help.

6

no
my background is white. and I’m not using blending

7

Do you try it on both amd card and nvidia card?
You need to specify the input and output layout for geometry shader either in the shader or in the application.

8

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