Rendering textured quad with alpha using GL methods

Unity Engine
1

Hi,

I’m trying to render a textured quad in OnRenderImage using GL methods. I’ve got a Material with this shader:

Shader "Custom/MarkerShader" {
	Properties {
		_Color ("Main Color", Color) = (1,1,1,1)
		_SpecColor ("Spec Color", Color) = (1,1,1,0)
		_Emission ("Emissive Color", Color) = (0,0,0,0)
		_Shininess ("Shininess", Range (0.1, 1)) = 0.7
		_MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
	}
 
	SubShader {
		Tags {"RenderType"="Transparent" "Queue"="Transparent"}
		// Render normally
		Pass {
			ZWrite Off
			Blend SrcAlpha OneMinusSrcAlpha
			ColorMask RGB
			Material {
				Diffuse [_Color]
				Ambient [_Color]
				Shininess [_Shininess]
				Specular [_SpecColor]
				Emission [_Emission]
			}
			Lighting On
			SetTexture [_MainTex] {
				Combine texture * primary DOUBLE, texture * primary
			} 
		}
	}
}

In the inspector I set Main Color and Spec Color to (0,0,0,1), Emission to (0,1,0,1) and Shininess to 0. The texture is set to a png with alpha channel. I import the texture with “Alpha is Transparency” checked. In OnRenderImage, I first blit src to dst, then I try to draw the textured quad like this:

	Material mat = this.MarkerMaterial;

		GL.Color( Color.white );

		mat.SetPass( 0 );

		GL.PushMatrix();
		{
			GL.LoadOrtho();
			GL.LoadIdentity();

			pos.x *= ar;
			pos.y = 1.0f - pos.y;
			GL.MultMatrix( Matrix4x4.Scale( new Vector3( 1.0f / ar, 1.0f, 1.0f ) ) * Matrix4x4.TRS( pos, q, Vector3.one ) );

			GL.Begin( GL.QUADS );
			{
				GL.Vertex3( -markerWidth, -markerHeight, 0.0f );
				GL.Vertex3( -markerWidth, markerHeight, 0.0f );
				GL.Vertex3( markerWidth, markerHeight, 0.0f );
				GL.Vertex3( markerWidth, -markerHeight, 0.0f );
			}
			GL.End();
		}
		GL.PopMatrix();

When I try to render using the texture including alpha channel, I see nothing. When I replace it by another texture without alpha, it works.

Any ideas about what I’m doing wrong?

Thanks a lot.

Now, that's embarrassing. When I switched from lines to quad I forgot that I now have to also set the uv coordinates. I was so distracted by all the ShaderLab syntax I'm not quite familiar with that I thought I must have made a mistake there somewhere.
2

You need to assign texture coordinates before you submit a vertex. Use GL.TexCoord2(x, y); before each vertex.

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