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I am trying to make some first steps with OpenGL Shaders.  At the beginning i have a patch with a jit.gl.mesh object. It contains 3 Lines with different colors on the end and a line_width set to 2. The Output looks how it is expected:

In the next Step i have tried to write a shader which does contain vertex, geometry and fragment shaders:

And i added a jit.gl.shader object to use with jit.gl.mesh. 

So how you can See the results between the patch without and with the shader looks different:

I guess the Problems are in my Shader Code. I would be glad when someone could take a look on my shader Code and give me some hints. 

Hi there,

I am trying to make some first steps with OpenGL Shaders.  At the beginning i have a patch with a jit.gl.mesh object. It...

jitglmesh-with-jitglshader

to your [jit.gl.mesh] to get the actual shader and start from here.

You should get something like below. Oh and mind that this shader shoud change depending on your [jit.gl.mesh] attributes. So if you want to dynamicaly change some attributes (let's say the draw mode) with your custom shader, make sure to export the built-in shader for any situation and re-assemble everything yourself.

<jittershader name="linewidth-flat-line_strip-color_vao">
	<description>
		An auto-generated shader for simulating deprecated OpenGL features in OpenGL 3.2+
	</description>
	<param name="position" type="vec3" state="POSITION" />
	<param name="modelViewProjectionMatrix" type="mat4" state="MODELVIEW_PROJECTION_MATRIX" />
	<param name="color" type="vec4" state="COLOR" />
	<param name="viewport" type="vec2" state="VIEWPORT" />
	<param name="line_width" type="float" state="LINE_WIDTH" />
	<language name="glsl" version="1.5">
		<bind param="position" program="vp" />
		<bind param="modelViewProjectionMatrix" program="vp" />
		<bind param="color" program="vp" />
		<bind param="viewport" program="gp" />
		<bind param="line_width" program="gp" />
		<program name="vp" type="vertex">
			<![CDATA[
			// Preprocessor
			#version 330 core
			
			// Definitions
			
			
			// Uniforms
			uniform mat4 modelViewProjectionMatrix;
	
			// Attributes
			in vec3 position;
			in vec4 color;

			// Output
			out jit_PerVertex {
				flat vec4 color;

			} jit_out;

			// Library functions

			void main() {
				
				vec4 pos4 = vec4(position.xyz, 1.);
				
				gl_Position = modelViewProjectionMatrix * pos4;	
				jit_out.color = color;
			}
		]]>
		</program>
		<program name="gp" vertices_out="4" input_type="lines" output_type="triangle_strip" type="geometry">
			<![CDATA[
		#version 330 core
		
		layout( lines ) in;
		layout( triangle_strip, max_vertices = 4 ) out;
		
		in jit_PerVertex {
			flat vec4 color; 
			
		} jit_in[];
		
		out jit_PerVertex {
			flat vec4 color; 
			
		};
		
		uniform float line_width;
		uniform vec2 viewport;
		vec2 toScreenSpace( vec4 vertex )
		{
			return vec2( vertex.xy / vertex.w ) * viewport;
		}
		vec4 toWorldSpace( vec4 vertex )
		{
			return vec4(( vertex.xy * vertex.w ) / viewport, vertex.zw);
		}
		
		void main() {
			
			vec2 p0 = toScreenSpace( gl_in[0].gl_Position );
			vec2 p1 = toScreenSpace( gl_in[1].gl_Position );
			vec2 v0 = normalize( p1 - p0 );
			vec2 n0 = vec2( -v0.y, v0.x ) * line_width;
		
			gl_Position = toWorldSpace(vec4( ( p0 + n0 ), gl_in[0].gl_Position.zw ));
			color = jit_in[0].color; 
			
			EmitVertex();
			gl_Position = toWorldSpace(vec4( ( p0 - n0 ), gl_in[0].gl_Position.zw ));
			color = jit_in[0].color; 
			
			EmitVertex();
			gl_Position = toWorldSpace(vec4( ( p1 + n0 ), gl_in[1].gl_Position.zw ));
			color = jit_in[1].color; 
			
			EmitVertex();
			gl_Position = toWorldSpace(vec4( ( p1 - n0 ), gl_in[1].gl_Position.zw ));
			color = jit_in[1].color; 
			
			EmitVertex();
			EndPrimitive();
			
		}	
		
		]]>
		</program>
		<program name="fp" type="fragment">
			<![CDATA[
			#version 330 core
			
			in jit_PerVertex {
				flat vec4 color;
			} jit_in;
			out vec4 color;
			void main() {
			
				color = jit_in.color;
			}	
		]]>
		</program>
	</language>
</jittershader>

jit.gl.mesh with jit.gl.shader