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ee940a3d0d
So we can get to the point where cogl.h is merely an aggregation of header includes for the 1.x api this moves all the function prototypes and type definitions into a cogl-context.h and a new cogl1-context.h. Ideally no code internally should ever need to include cogl.h as it just represents the public facing header for accessing the 1.x api which should only be used by Clutter. Reviewed-by: Neil Roberts <neil@linux.intel.com>
133 lines
4.5 KiB
C
133 lines
4.5 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 License
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* 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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* Authors:
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* Robert Bragg <robert@linux.intel.com>
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*/
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#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
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#error "Only <cogl/cogl.h> can be included directly."
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#endif
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#ifndef __COGL_INDICES_H__
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#define __COGL_INDICES_H__
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/* We forward declare the CoglIndices type here to avoid some circular
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* dependency issues with the following headers.
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*/
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typedef struct _CoglIndices CoglIndices;
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#include <cogl/cogl-index-buffer.h>
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-index-range
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* @short_description: Fuctions for declaring a range of vertex indices
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* stored in a #CoglIndexBuffer.
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*
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* Indices allow you to avoid duplicating vertices in your vertex data
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* by virtualizing your data and instead providing a sequence of index
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* values that tell the GPU which data should be used for each vertex.
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*
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* If the GPU is given a squence of indices it doesn't simply walk
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* through each vertex of your data in order it will instead walk
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* through the indices which can provide random access to the
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* underlying data.
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*
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* Since it's very common to have duplicate vertices when describing a
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* shape as a list of triangles it can often be a significant space
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* saving to describe geometry using indices. Reducing the size of
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* your models can make it cheaper to map them into the GPU by
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* reducing the demand on memory bandwidth and may help to make better
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* use of your GPUs internal vertex caching.
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*
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* For example, to describe a quadrilateral as 2 triangles for the GPU
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* you could either provide data with 6 vertices or instead with
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* indices you can provide vertex data for just 4 vertices and an
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* index buffer that specfies the 6 vertices by indexing the shared
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* vertices multiple times.
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*
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* |[
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* CoglVertex2f quad_vertices[] = {
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* {x0, y0}, //0 = top left
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* {x1, y1}, //1 = bottom left
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* {x2, y2}, //2 = bottom right
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* {x3, y3}, //3 = top right
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* };
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* //tell the gpu how to interpret the quad as 2 triangles...
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* unsigned char indices[] = {0, 1, 2, 0, 2, 3};
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* ]|
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*
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* Even in the above illustration we see a saving of 10bytes for one
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* quad compared to having data for 6 vertices and no indices but if
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* you need to draw 100s or 1000s of quads then its really quite
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* significant.
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*
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* Something else to consider is that often indices can be defined
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* once and remain static while the vertex data may change for
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* animations perhaps. That means you may be able to ignore the
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* negligable cost of mapping your indices into the GPU if they don't
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* ever change.
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*
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* The above illustration is actually a good example of static indices
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* because it's really common that developers have quad mesh data that
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* they need to display and we know exactly what that indices array
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* needs to look like depending on the number of quads that need to be
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* drawn. It doesn't matter how the quads might be animated and
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* changed the indices will remain the same. Cogl even has a utility
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* (cogl_get_rectangle_indices()) to get access to re-useable indices
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* for drawing quads as above.
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*/
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CoglIndices *
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cogl_indices_new (CoglContext *context,
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CoglIndicesType type,
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const void *indices_data,
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int n_indices);
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CoglIndices *
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cogl_indices_new_for_buffer (CoglIndicesType type,
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CoglIndexBuffer *buffer,
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gsize offset);
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CoglIndexBuffer *
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cogl_indices_get_buffer (CoglIndices *indices);
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CoglIndicesType
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cogl_indices_get_type (CoglIndices *indices);
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gsize
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cogl_indices_get_offset (CoglIndices *indices);
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void
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cogl_indices_set_offset (CoglIndices *indices,
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gsize offset);
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CoglIndices *
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cogl_get_rectangle_indices (CoglContext *context, int n_rectangles);
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G_END_DECLS
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#endif /* __COGL_INDICES_H__ */
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