fecaaea132
Instead of drawing paths using the stencil buffer trick, it now tesselates the path into triangles using the GLU tesselator and renders them directly. A vbo is created with one vertex for each node on the path. The tesselator is used to generate a series of indices into the vbo as triangles. The tesselator's output of strips and fans is converted into GL_TRIANGLES so that it can be rendered with a single draw call (but the vertices are still shared via the indices). The vbo is stored with the path so that if the application uses retained paths then Cogl won't have to tessellate again. The vertices also have texture coordinates associated with them so that it can replicate the old behaviour of drawing a material with a texture by fitting the texture to the bounding box of the path and then clipping it. However if the texture contains waste or is sliced then the vertex buffer code will refuse to draw it. In this case it will revert back to drawing the path into the stencil buffer and then drawing the material as a clipped quad. The VBO is used even when setting up the stencil buffer for clipping to a path because the tessellated geometry may cover less area. The old scanline rasterizer has been removed because the tesselator should work equally well on drivers with no stencil buffer.
104 lines
2.3 KiB
C
104 lines
2.3 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2010 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#ifndef __COGL_PATH_PRIVATE_H
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#define __COGL_PATH_PRIVATE_H
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#include "cogl-handle.h"
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#define COGL_PATH(tex) ((CoglPath *)(tex))
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typedef struct _floatVec2
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{
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float x;
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float y;
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} floatVec2;
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typedef struct _CoglPathNode
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{
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float x;
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float y;
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unsigned int path_size;
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} CoglPathNode;
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typedef struct _CoglBezQuad
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{
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floatVec2 p1;
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floatVec2 p2;
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floatVec2 p3;
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} CoglBezQuad;
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typedef struct _CoglBezCubic
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{
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floatVec2 p1;
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floatVec2 p2;
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floatVec2 p3;
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floatVec2 p4;
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} CoglBezCubic;
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typedef struct _CoglPathData CoglPathData;
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struct _CoglPath
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{
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CoglHandleObject _parent;
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CoglPathData *data;
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};
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struct _CoglPathData
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{
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unsigned int ref_count;
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GArray *path_nodes;
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floatVec2 path_start;
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floatVec2 path_pen;
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unsigned int last_path;
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floatVec2 path_nodes_min;
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floatVec2 path_nodes_max;
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CoglHandle vbo;
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unsigned int vbo_n_vertices;
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CoglHandle vbo_indices;
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unsigned int vbo_n_indices;
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};
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/* This is an internal version of cogl_path_new that doesn't affect
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the current path and just creates a new handle */
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CoglPath *
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_cogl_path_new (void);
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void
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_cogl_add_path_to_stencil_buffer (CoglPath *path,
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gboolean merge,
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gboolean need_clear);
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void
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_cogl_path_get_bounds (CoglPath *path,
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float *min_x,
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float *min_y,
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float *max_x,
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float *max_y);
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#endif /* __COGL_PATH_PRIVATE_H */
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