draw lines anti-aliased (opengl vcl)
Change-Id: I3a67da89cedbb6a58b2556abf4553857125af5a6
This commit is contained in:
Luboš Luňák
@@ -402,33 +402,150 @@ void OpenGLSalGraphicsImpl::DrawPoint( long nX, long nY )
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void OpenGLSalGraphicsImpl::DrawLine( long nX1, long nY1, long nX2, long nY2 )
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{
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GLfloat pPoints[4];
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if( nX1 == nX2 || nY1 == nY2 )
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{ // horizontal/vertical, no need for AA
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GLfloat pPoints[4];
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pPoints[0] = (2 * nX1) / GetWidth() - 1.0;
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pPoints[1] = 1.0f - 2 * nY1 / GetHeight();
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pPoints[2] = (2 * nX2) / GetWidth() - 1.0;;
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pPoints[3] = 1.0f - 2 * nY2 / GetHeight();
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pPoints[0] = (2 * nX1) / GetWidth() - 1.0;
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pPoints[1] = 1.0f - 2 * nY1 / GetHeight();
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pPoints[2] = (2 * nX2) / GetWidth() - 1.0;;
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pPoints[3] = 1.0f - 2 * nY2 / GetHeight();
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mpProgram->SetVertices( pPoints );
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glDrawArrays( GL_LINES, 0, 2 );
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mpProgram->SetVertices( pPoints );
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glDrawArrays( GL_LINES, 0, 2 );
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return;
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}
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// Draw the line anti-aliased. Based on code with the following notice:
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/* Drawing nearly perfect 2D line segments in OpenGL
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* You can use this code however you want.
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* I just hope you to cite my name and the page of this technique:
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* http://artgrammer.blogspot.com/2011/05/drawing-nearly-perfect-2d-line-segments.html
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* http://www.codeproject.com/KB/openGL/gllinedraw.aspx
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*
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* Enjoy. Chris Tsang.*/
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if( !UseProgram( "textureVertexShader", "linearGradientFragmentShader" ) )
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return;
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mpProgram->SetColorf( "start_color", mnLineColor, 0.0f );
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mpProgram->SetColorf( "end_color", mnLineColor, 1.0f );
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double x1 = nX1;
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double y1 = nY1;
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double x2 = nX2;
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double y2 = nY2;
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const int w = 1; // line width
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double t;
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double R;
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//determine parameters t,R
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switch( w )
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{
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case 0:
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return;
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case 1:
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t=0.05;
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R=0.768;
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break;
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case 2:
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t=0.38;
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R=1.08;
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break;
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case 3:
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t=0.96;
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R=1.08;
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break;
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case 4:
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t=1.44;
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R=1.08;
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break;
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case 5:
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t=1.9;
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R=1.08;
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break;
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default:
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t=2.5+(w-6)*0.50;
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R=1.08;
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break;
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}
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//determine angle of the line to horizontal
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double tx=0,ty=0; //core thinkness of a line
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double Rx=0,Ry=0; //fading edge of a line
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double cx=0,cy=0; //cap of a line
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double dx=x2-x1;
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double dy=y2-y1;
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if ( w < 3)
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{ //approximate to make things even faster
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double m=dy/dx;
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//and calculate tx,ty,Rx,Ry
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if ( m>-0.4142 && m<=0.4142)
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{
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// -22.5< angle <= 22.5, approximate to 0 (degree)
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tx=t*0.1; ty=t;
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Rx=R*0.6; Ry=R;
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}
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else if ( m>0.4142 && m<=2.4142)
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{
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// 22.5< angle <= 67.5, approximate to 45 (degree)
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tx=t*-0.7071; ty=t*0.7071;
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Rx=R*-0.7071; Ry=R*0.7071;
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}
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else if ( m>2.4142 || m<=-2.4142)
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{
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// 67.5 < angle <=112.5, approximate to 90 (degree)
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tx=t; ty=t*0.1;
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Rx=R; Ry=R*0.6;
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}
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else if ( m>-2.4142 && m<-0.4142)
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{
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// 112.5 < angle < 157.5, approximate to 135 (degree)
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tx=t*0.7071; ty=t*0.7071;
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Rx=R*0.7071; Ry=R*0.7071;
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}
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else
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assert( false );
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}
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else
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{ //calculate to exact
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dx=y1-y2;
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dy=x2-x1;
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double L=sqrt(dx*dx+dy*dy);
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dx/=L;
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dy/=L;
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cx=-0.6*dy; cy=0.6*dx;
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tx=t*dx; ty=t*dy;
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Rx=R*dx; Ry=R*dy;
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}
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GLfloat vertices[]=
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{
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#define convertX( x ) GLfloat( (2 * (x)) / GetWidth() - 1.0f)
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#define convertY( y ) GLfloat( 1.0f - (2 * (y)) / GetHeight())
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convertX(x1-tx-Rx), convertY(y1-ty-Ry), //fading edge1
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convertX(x2-tx-Rx), convertY(y2-ty-Ry),
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convertX(x1-tx),convertY(y1-ty), //core
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convertX(x2-tx),convertY(y2-ty),
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convertX(x1+tx),convertY(y1+ty),
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convertX(x2+tx),convertY(y2+ty),
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convertX(x1+tx+Rx), convertY(y1+ty+Ry), //fading edge2
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convertX(x2+tx+Rx), convertY(y2+ty+Ry)
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#undef convertX
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#undef convertY
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};
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GLfloat aTexCoord[16] = { 0, 0, 1, 0, 2, 1, 3, 1, 4, 1, 5, 1, 6, 0, 7, 0 };
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mpProgram->SetTextureCoord( aTexCoord );
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mpProgram->SetVertices( vertices );
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glDrawArrays(GL_TRIANGLE_STRIP, 0, 8);
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}
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void OpenGLSalGraphicsImpl::DrawLines( sal_uInt32 nPoints, const SalPoint* pPtAry, bool bClose )
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{
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std::vector<GLfloat> aPoints(nPoints * 2);
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sal_uInt32 i, j;
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for( i = 0, j = 0; i < nPoints; i++ )
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{
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aPoints[j++] = (2 * pPtAry[i].mnX) / GetWidth() - 1.0f;
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aPoints[j++] = 1.0f - (2 * pPtAry[i].mnY) / GetHeight();
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}
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mpProgram->SetVertices( &aPoints[0] );
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for( int i = 0; i < int(nPoints) - 1; ++i )
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DrawLine( pPtAry[ i ].mnX, pPtAry[ i ].mnY, pPtAry[ i + 1 ].mnX, pPtAry[ i + 1 ].mnY );
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if( bClose )
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glDrawArrays( GL_LINE_LOOP, 0, nPoints );
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else
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glDrawArrays( GL_LINE_STRIP, 0, nPoints );
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DrawLine( pPtAry[ nPoints - 1 ].mnX, pPtAry[ nPoints - 1 ].mnY, pPtAry[ 0 ].mnX, pPtAry[ 0 ].mnY );
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}
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void OpenGLSalGraphicsImpl::DrawConvexPolygon( sal_uInt32 nPoints, const SalPoint* pPtAry )
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