1 pixel wide lines using OpenGL shaders. (20c86db7) · Commits · Elphel / kicad-source-mirror

common/gal/opengl/opengl_gal.cpp

+42 −49

Original line number	Diff line number	Diff line
		@@ -783,22 +783,23 @@ void OPENGL_GAL::DrawCircle( const VECTOR2D& aCenterPoint, double aRadius )
		color4( fillColor.r, fillColor.g, fillColor.b, fillColor.a );

		/* Draw a triangle that contains the circle, then shade it leaving only the circle.
		Parameters given to setShader are relative coordinates of the triangle's vertices.
		Parameters given to setShader are indices of the triangle's vertices
		(if you want to understand more, check the vertex shader source [shader.vert]).
		Shader uses this coordinates to determine if fragments are inside the circle or not.
		v2
		/\
		//\\
		v0 /_\/_\ v1
		*/
		setShader( SHADER_FILLED_CIRCLE, -sqrt( 3.0f ), -1.0f );
		vertex3( aCenterPoint.x - aRadius * sqrt( 3.0f ), // v0
		aCenterPoint.y - aRadius, layerDepth );
		setShader( SHADER_FILLED_CIRCLE, 1.0 );
		vertex3( aCenterPoint.x - aRadius * sqrt( 3.0f ),
		aCenterPoint.y - aRadius, layerDepth ); // v0

		setShader( SHADER_FILLED_CIRCLE, sqrt( 3.0f ), -1.0f );
		vertex3( aCenterPoint.x + aRadius * sqrt( 3.0f ), // v1
		aCenterPoint.y - aRadius, layerDepth );
		setShader( SHADER_FILLED_CIRCLE, 2.0 );
		vertex3( aCenterPoint.x + aRadius * sqrt( 3.0f ),
		aCenterPoint.y - aRadius, layerDepth ); // v1

		setShader( SHADER_FILLED_CIRCLE, 0.0f, 2.0f );
		setShader( SHADER_FILLED_CIRCLE, 3.0 );
		vertex3( aCenterPoint.x, aCenterPoint.y + aRadius * 2.0f, layerDepth ); // v2
		}

		@@ -807,30 +808,25 @@ void OPENGL_GAL::DrawCircle( const VECTOR2D& aCenterPoint, double aRadius )
		color4( strokeColor.r, strokeColor.g, strokeColor.b, strokeColor.a );

		/* Draw a triangle that contains the circle, then shade it leaving only the circle.
		Parameters given to setShader are relative coordinates of the triangle's vertices
		Parameters given to setShader are indices of the triangle's vertices
		(if you want to understand more, check the vertex shader source [shader.vert]).
		and the line width. Shader uses this coordinates to determine if fragments are inside
		the circle or not. Width parameter has to be passed as a ratio of inner radius
		to outer radius.
		the circle or not.
		v2
		/\
		//\\
		v0 /_\/_\ v1
		*/
		float outerRadius = aRadius + ( lineWidth / 2.0f );
		float innerRadius = aRadius - ( lineWidth / 2.0f );
		float relWidth = innerRadius / outerRadius;
		setShader( SHADER_STROKED_CIRCLE, 1.0, aRadius, lineWidth );
		vertex3( aCenterPoint.x - aRadius * sqrt( 3.0f ),
		aCenterPoint.y - aRadius, layerDepth ); // v0

		setShader( SHADER_STROKED_CIRCLE, -sqrt( 3.0f ), -1.0f, relWidth );
		vertex3( aCenterPoint.x - outerRadius * sqrt( 3.0f ), // v0
		aCenterPoint.y - outerRadius, layerDepth );
		setShader( SHADER_STROKED_CIRCLE, 2.0, aRadius, lineWidth );
		vertex3( aCenterPoint.x + aRadius * sqrt( 3.0f ),
		aCenterPoint.y - aRadius, layerDepth ); // v1

		setShader( SHADER_STROKED_CIRCLE, sqrt( 3.0f ), -1.0f, relWidth );
		vertex3( aCenterPoint.x + outerRadius * sqrt( 3.0f ), // v1
		aCenterPoint.y - outerRadius, layerDepth );

		setShader( SHADER_STROKED_CIRCLE, 0.0f, 2.0f, relWidth );
		vertex3( aCenterPoint.x, // v2
		aCenterPoint.y + outerRadius * 2.0f, layerDepth );
		setShader( SHADER_STROKED_CIRCLE, 3.0, aRadius, lineWidth );
		vertex3( aCenterPoint.x, aCenterPoint.y + aRadius * 2.0f, layerDepth ); // v2
		}

		return;
		@@ -931,20 +927,21 @@ void OPENGL_GAL::drawFilledSemiCircle( const VECTOR2D& aCenterPoint, double aRad
		Rotate( aAngle );

		/* Draw a triangle that contains the semicircle, then shade it to leave only the semicircle.
		Parameters given to setShader are relative coordinates of the triangle's vertices.
		Parameters given to setShader are indices of the triangle's vertices
		(if you want to understand more, check the vertex shader source [shader.vert]).
		Shader uses this coordinates to determine if fragments are inside the semicircle or not.
		v2
		/\
		/__\
		v0 //__\\ v1
		*/
		setShader( SHADER_FILLED_CIRCLE, -3.0f / sqrt( 3.0f ), 0.0f );
		setShader( SHADER_FILLED_CIRCLE, 4.0f );
		vertex3( -aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth ); // v0

		setShader( SHADER_FILLED_CIRCLE, 3.0f / sqrt( 3.0f ), 0.0f );
		setShader( SHADER_FILLED_CIRCLE, 5.0f );
		vertex3( aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth ); // v1

		setShader( SHADER_FILLED_CIRCLE, 0.0f, 2.0f );
		setShader( SHADER_FILLED_CIRCLE, 6.0f );
		vertex3( 0.0f, aRadius * 2.0f, layerDepth ); // v2

		Restore();
		@@ -973,26 +970,22 @@ void OPENGL_GAL::drawStrokedSemiCircle( const VECTOR2D& aCenterPoint, double aRa
		Rotate( aAngle );

		/* Draw a triangle that contains the semicircle, then shade it to leave only the semicircle.
		Parameters given to setShader are relative coordinates of the triangle's vertices
		and the line width. Shader uses this coordinates to determine if fragments are inside
		the semicircle or not. Width parameter has to be passed as a ratio of inner radius
		to outer radius.
		Parameters given to setShader are indices of the triangle's vertices
		(if you want to understand more, check the vertex shader source [shader.vert]), the
		radius and the line width. Shader uses this coordinates to determine if fragments are
		inside the semicircle or not.
		v2
		/\
		/__\
		v0 //__\\ v1
		*/
		float outerRadius = aRadius;
		float innerRadius = aRadius - lineWidth;
		float relWidth = innerRadius / outerRadius;

		setShader( SHADER_STROKED_CIRCLE, -3.0f / sqrt( 3.0f ), 0.0f, relWidth );
		setShader( SHADER_STROKED_CIRCLE, 4.0f, aRadius, lineWidth );
		vertex3( -aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth ); // v0

		setShader( SHADER_STROKED_CIRCLE, 3.0f / sqrt( 3.0f ), 0.0f, relWidth );
		setShader( SHADER_STROKED_CIRCLE, 5.0f, aRadius, lineWidth );
		vertex3( aRadius * 3.0f / sqrt( 3.0f ), 0.0f, layerDepth ); // v1

		setShader( SHADER_STROKED_CIRCLE, 0.0f, 2.0f, relWidth );
		setShader( SHADER_STROKED_CIRCLE, 6.0f, aRadius, lineWidth );
		vertex3( 0.0f, aRadius * 2.0f, layerDepth ); // v2

		Restore();

common/gal/opengl/shader.frag

+10 −5

Original line number	Diff line number	Diff line
		@@ -32,20 +32,25 @@ const float SHADER_FILLED_CIRCLE = 2.0;
		const float SHADER_STROKED_CIRCLE = 3.0;

		varying vec4 shaderParams;
		varying vec2 circleCoords;

		void filledCircle( vec2 aCoord )
		{
		if( dot( aCoord, aCoord ) < 1.0 )
		if( dot( aCoord, aCoord ) < 1.0f )
		gl_FragColor = gl_Color;
		else
		discard;
		}


		void strokedCircle( vec2 aCoord, float aWidth )
		void strokedCircle( vec2 aCoord, float aRadius, float aWidth )
		{
		float outerRadius = aRadius;
		float innerRadius = aRadius - aWidth;
		float relWidth = innerRadius / outerRadius;

		if( ( dot( aCoord, aCoord ) < 1.0 ) &&
		( dot( aCoord, aCoord ) > aWidth * aWidth ) )
		( dot( aCoord, aCoord ) > relWidth * relWidth ) )
		gl_FragColor = gl_Color;
		else
		discard;
		@@ -56,11 +61,11 @@ void main()
		{
		if( shaderParams[0] == SHADER_FILLED_CIRCLE )
		{
		filledCircle( vec2( shaderParams[1], shaderParams[2] ) );
		filledCircle( circleCoords );
		}
		else if( shaderParams[0] == SHADER_STROKED_CIRCLE )
		{
		strokedCircle( vec2( shaderParams[1], shaderParams[2] ), shaderParams[3] );
		strokedCircle( circleCoords, shaderParams[2], shaderParams[3] );
		}
		else
		{

common/gal/opengl/shader.vert

+37 −2

Original line number	Diff line number	Diff line
		@@ -31,8 +31,12 @@ const float SHADER_LINE = 1.0;
		const float SHADER_FILLED_CIRCLE = 2.0;
		const float SHADER_STROKED_CIRCLE = 3.0;

		// Minimum line width
		const float MIN_WIDTH = 1.0;

		attribute vec4 attrShaderParams;
		varying vec4 shaderParams;
		varying vec2 circleCoords;

		void main()
		{
		@@ -45,8 +49,8 @@ void main()
		float worldScale = gl_ModelViewMatrix[0][0];
		float scale;

		// Make lines appear to be at least 1 pixel width
		if( worldScale * lineWidth < 1.0 )
		// Make lines appear to be at least 1 pixel wide
		if( worldScale * lineWidth < MIN_WIDTH )
		scale = 1.0 / ( worldScale * lineWidth );
		else
		scale = 1.0;
		@@ -54,6 +58,37 @@ void main()
		gl_Position = gl_ModelViewProjectionMatrix *
		( gl_Vertex + vec4( shaderParams.yz * scale, 0.0, 0.0 ) );
		}
		else if( ( shaderParams[0] == SHADER_STROKED_CIRCLE ) \|\|
		( shaderParams[0] == SHADER_FILLED_CIRCLE ) )
		{
		// Compute relative circle coordinates basing on indices
		// Circle
		if( shaderParams[1] == 1.0f )
		circleCoords = vec2( -sqrt( 3.0f ), -1.0f );
		else if( shaderParams[1] == 2.0f )
		circleCoords = vec2( sqrt( 3.0f ), -1.0f );
		else if( shaderParams[1] == 3.0f )
		circleCoords = vec2( 0.0f, 2.0f );

		// Semicircle
		else if( shaderParams[1] == 4.0f )
		circleCoords = vec2( -3.0f / sqrt( 3.0f ), 0.0f );
		else if( shaderParams[1] == 5.0f )
		circleCoords = vec2( 3.0f / sqrt( 3.0f ), 0.0f );
		else if( shaderParams[1] == 6.0f )
		circleCoords = vec2( 0.0f, 2.0f );

		// Make the line appear to be at least 1 pixel wide
		float lineWidth = shaderParams[3];
		float worldScale = gl_ModelViewMatrix[0][0];
		float scale;

		// Make lines appear to be at least 1 pixel width
		if( worldScale * lineWidth < MIN_WIDTH )
		shaderParams[3] = shaderParams[3] / ( worldScale * lineWidth );

		gl_Position = ftransform();
		}
		else
		{
		// Pass through the coordinates like in the fixed pipeline

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