This group documents the symbols and varyings of the built in shaders provided by the GLSL module (which is used by both the GL and GLES backends. More...

This group documents the symbols and varyings of the built in shaders provided by the GLSL module (which is used by both the GL and GLES backends.

The following symbols are available as keyed by the values within a fastuidraw::PainterShaderSet.

For fastuidraw::PainterShaderSet::stroke_shader() and each fastuidraw::PainterStrokeShader of fastuidraw::PainterShaderSet::dashed_stroke_shader(), there is the following. For the vertex shaders there are the public symbols:

fastuidraw_stroking_distance gives the distance from the start of the contour along the path
fastuidraw_stroking_contour_length gives the length of the contour
fastuidraw_stroking_edge_length gives the length of the edge
fastuidraw_stroking_edge_start gives how far along the path the start of the edge is The non anti-aliased shaders (i.e. fastuidraw::PainterStrokeShader::non_aa_shader), have the following symbols in the fragment shader exposed:
fastuidraw_stroking_distance the distance from the start of the contour along the path
fastuidraw_stroking_distance_fwidth fwidth of fastuidraw_stroking_distance. Use this value to perform anti-aliasing coverage computations
fastuidraw_stroking_relative_distance_from_center this value is 0.0 on the path and grows to 1.0 at the stroking boundary
fastuidraw_stroking_distance_fwidth fwidth of fastuidraw_stroking_relative_distance_from_center. Use this value to perform anti-aliasing coverage computations The anti-aliasing shaders (i.e. fastuidraw::PainterStrokeShader::aa_shader) are two pass shaders where the coverage shader (i.e. fastuidraw::PainterItemShader::coverage_shader()) has the above symbols in fragment shader (and also the vertex symbols in the vertex shader), but the item shader only has the vertex shader symbols but not the fragment shader symbols.

Each shader present in fastuidraw::PainterShaderSet::brush_shaders() has the two varyings:

fastuidraw_brush_p_x which gives the x-coordinate of the brush
fastuidraw_brush_p_y which gives the y-coordinate of the brush The fastuidraw::PainterGradientBrushShader::linear_sub_shader() has the varyings:
fastuidraw_brush_gradient_p0_x the x-coordinate of the start position of the linear gradient
fastuidraw_brush_gradient_p0_y the y-coordinate of the start position of the linear gradient
fastuidraw_brush_gradient_p1_x the x-coordinate of the end position of the linear gradient
fastuidraw_brush_gradient_p1_y the y-coordinate of the end position of the linear gradient The fastuidraw::PainterGradientBrushShader::radial_sub_shader() has the varyings:
fastuidraw_brush_gradient_p0_x the x-coordinate of the start position of the radial gradient
fastuidraw_brush_gradient_p0_y the y-coordinate of the start position of the radial gradient
fastuidraw_brush_gradient_r0 the start radius of the radial gradient
fastuidraw_brush_gradient_p1_x the x-coordinate of the end position of the radial gradient
fastuidraw_brush_gradient_p1_y the y-coordinate of the end position of the radial gradient
fastuidraw_brush_gradient_r1 the end radius of the radial gradient The fastuidraw::PainterGradientBrushShader::sweep_sub_shader() has the varyings:
fastuidraw_brush_gradient_sweep_point_x the x-coordinate of the sweep point
fastuidraw_brush_gradient_sweep_point_y the y-coordinate of the sweep point
fastuidraw_brush_gradient_sweep_angle the start angle of the sweep gradient
fastuidraw_brush_gradient_sweep_sign_factor the signed multiplier of the sweep gradient. The fastuidraw::PainterGradientBrushShader::sub_shader() has all of the above varyings (since it encompasses all of the gradients) either directly or realized as aliases.

The standard brush, fastuidraw::PainterBrushShaderSet::standard_brush(), is itself realized as a chain shader with the image of the brush accessible via its dependee named image_brush, and the gradient via the dependee name gradient_brush.