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It's now possible to add arrays of indices to a Cogl vertex buffer and they will be put into an OpenGL vertex buffer object. Since it's quite common for index arrays to be static it saves the OpenGL driver from having to validate them repeatedly. This changes the cogl_vertex_buffer_draw_elements API: It's no longer possible to provide a pointer to an index array at draw time. So cogl_vertex_buffer_draw_elements now takes an indices identifier that should correspond to an idendifier returned when calling cogl_vertex_buffer_add_indices ()
366 lines
13 KiB
C
366 lines
13 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) 2008,2009 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, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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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_VERTEX_BUFFER_H__
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#define __COGL_VERTEX_BUFFER_H__
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#include <glib.h>
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#include <cogl/cogl-types.h>
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-vertex-buffer
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* @short_description: An API for submitting extensible arrays of vertex
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* attributes to be mapped into the GPU for fast
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* drawing.
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*
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* For example to describe a textured triangle, you could create a new cogl
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* vertex buffer with 3 vertices, and then you might add 2 attributes for each
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* vertex:
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* <orderedlist>
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* <listitem>
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* a "gl_Position" describing the (x,y,z) position for each vertex.
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* </listitem>
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* <listitem>
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* a "gl_MultiTexCoord0" describing the (tx,ty) texture coordinates for each
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* vertex.
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* </listitem>
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* </orderedlist>
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*
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* The Vertex Buffer API is designed to be a fairly raw mechanism for
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* developers to be able to submit geometry to Cogl in a format that can be
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* directly consumed by an OpenGL driver and mapped into your GPU for fast
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* re-use. It is designed to avoid repeated validation of the attributes by the
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* driver; to minimize transport costs (e.g. considering indirect GLX
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* use-cases) and to potentially avoid repeated format conversions when
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* attributes are supplied in a format that is not natively supported by the
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* GPU.
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*
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* Although this API does allow you to modify attributes after they have been
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* submitted to the GPU you should be aware that modification is not that
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* cheap, since it implies validating the new data and potentially the
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* OpenGL driver will need to reformat it for the GPU.
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*
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* If at all possible think of tricks that let you re-use static attributes,
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* and if you do need to repeatedly update attributes (e.g. for some kind of
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* morphing geometry) then only update and re-submit the specific attributes
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* that have changed.
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*/
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/**
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* cogl_vertex_buffer_new:
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* @n_vertices: The number of vertices that your attributes will correspond to.
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*
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* This creates a Cogl handle for a new vertex buffer that you can then start
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* to add attributes too.
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*/
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CoglHandle
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cogl_vertex_buffer_new (guint n_vertices);
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/**
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* cogl_vertex_buffer_get_n_vertices:
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* @handle: A vertex buffer handle
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*
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* This returns the number of vertices that @handle represents
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*/
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guint
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cogl_vertex_buffer_get_n_vertices (CoglHandle handle);
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/**
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* cogl_vertex_buffer_add:
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* @handle: A vertex buffer handle
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* @attribute_name: The name of your attribute. It should be a valid GLSL
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* variable name and standard attribute types must use one
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* of following built-in names: (Note: they correspond to the
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* built-in names of GLSL)
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* <itemizedlist>
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* <listitem>"gl_Color"</listitem>
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* <listitem>"gl_Normal"</listitem>
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* <listitem>"gl_MultiTexCoord0, gl_MultiTexCoord1, ..."</listitem>
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* <listitem>"gl_Vertex"</listitem>
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* </itemizedlist>
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* To support adding multiple variations of the same attribute
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* the name can have a detail component, E.g.
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* "gl_Color::active" or "gl_Color::inactive"
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* @n_components: The number of components per attribute and must be 1,2,3 or 4
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* @gl_type: Specifies the data type of each component (GL_BYTE, GL_UNSIGNED_BYTE,
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* GL_SHORT, GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT or GL_FLOAT)
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* @normalized: If GL_TRUE, this specifies that values stored in an integer
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* format should be mapped into the range [-1.0, 1.0] or [0.1, 1.0]
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* for unsigned values. If GL_FALSE they are converted to floats
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* directly.
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* @stride: This specifies the number of bytes from the start of one attribute
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* value to the start of the next value (for the same attribute). So
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* for example with a position interleved with color like this:
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* XYRGBAXYRGBAXYRGBA, then if each letter represents a byte, the
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* stride for both attributes is 6. The special value 0 means the
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* values are stored sequentially in memory.
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* @pointer: This addresses the first attribute in the vertex array. (This
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* must remain valid until you either call
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* cogl_vertex_buffer_submit() or issue a draw call.)
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*
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* This function lets you add an attribute to a buffer. You either use one
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* of the built-in names such as "gl_Vertex", or "gl_MultiTexCoord0" to add
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* standard attributes, like positions, colors and normals or you can add
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* custom attributes for use in shaders.
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*
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* The number of vertices declared when calling cogl_vertex_buffer_new()
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* determines how many attribute values will be read from the supplied pointer.
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*
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* The data for your attribute isn't copied anywhere until you call
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* cogl_vertex_buffer_submit(), (or issue a draw call which automatically
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* submits pending attribute changes) so the supplied pointer must remain
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* valid until then. If you are updating an existing attribute (done by
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* re-adding it) then you still need to re-call cogl_vertex_buffer_submit() to
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* commit the changes to the GPU. (Be carefull to minimize the number of calls
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* to cogl_vertex_buffer_submit though.)
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*
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* Note: If you are interleving attributes it is assumed that each interleaved
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* attribute starts no farther than +- stride bytes from the other attributes
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* it is interleved with. I.e. this is ok:
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* <programlisting>
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* |-0-0-0-0-0-0-0-0-0-0|
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* </programlisting>
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* This is not ok:
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* <programlisting>
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* |- - - - -0-0-0-0-0-0 0 0 0 0|
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* </programlisting>
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* (Though you can have multiple groups of interleved attributes)
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*/
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void
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cogl_vertex_buffer_add (CoglHandle handle,
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const char *attribute_name,
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guint8 n_components,
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GLenum gl_type,
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gboolean normalized,
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guint16 stride,
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const void *pointer);
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/**
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* cogl_vertex_buffer_delete:
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* @handle: A vertex buffer handle
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* @attribute_name: The name of a previously added attribute
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*
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* This function deletes an attribute from a buffer. You will need to
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* call cogl_vertex_buffer_submit() or issue a draw call to commit this
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* change to the GPU.
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*/
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void
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cogl_vertex_buffer_delete (CoglHandle handle,
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const char *attribute_name);
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/**
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* cogl_vertex_buffer_submit:
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* @handle: A vertex buffer handle
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*
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* This function submits all the user added attributes to the GPU; once
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* submitted the attributes can be used for drawing.
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*
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* You should aim to minimize calls to this function since it implies
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* validating your data; it potentially incurs a transport cost (especially if
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* you are using GLX indirect rendering) and potentially a format conversion
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* cost if the GPU doesn't natively support any of the given attribute formats.
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*/
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void
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cogl_vertex_buffer_submit (CoglHandle handle);
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/**
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* cogl_vertex_buffer_disable:
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* @handle: A vertex buffer handle
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* @attribute_name: The name of the attribute you want to disable
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*
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* This function disables a previosuly added attribute.
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*
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* Since it can be costly to add and remove new attributes to buffers; to make
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* individual buffers more reuseable it is possible to enable and disable
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* attributes before using a buffer for drawing.
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*
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* You don't need to call cogl_vertex_buffer_submit() after using this function.
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*/
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void
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cogl_vertex_buffer_disable (CoglHandle handle,
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const char *attribute_name);
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/**
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* cogl_vertex_buffer_enable:
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* @handle: A vertex buffer handle
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* @attribute_name: The name of the attribute you want to enable
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*
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* This function enables a previosuly disabled attribute.
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*
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* Since it can be costly to add and remove new attributes to buffers; to make
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* individual buffers more reuseable it is possible to enable and disable
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* attributes before using a buffer for drawing.
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*
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* You don't need to call cogl_vertex_buffer_submit() after using this function
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*/
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void
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cogl_vertex_buffer_enable (CoglHandle handle,
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const char *attribute_name);
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/**
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* cogl_vertex_buffer_draw:
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* @handle: A vertex buffer handle
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* @mode: Specifies how the vertices should be interpreted, and should be
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* a valid GL primitive type:
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* <itemizedlist>
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* <listitem>GL_POINTS</listitem>
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* <listitem>GL_LINE_STRIP</listitem>
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* <listitem>GL_LINE_LOOP</listitem>
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* <listitem>GL_LINES</listitem>
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* <listitem>GL_TRIANGLE_STRIP</listitem>
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* <listitem>GL_TRIANGLE_FAN</listitem>
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* <listitem>GL_TRIANGLES</listitem>
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* </itemizedlist>
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* (Note: only types available in GLES are listed)
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* @first: Specifies the index of the first vertex you want to draw with
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* @count: Specifies the number of vertices you want to draw.
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*
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* This function lets you draw geometry using all or a subset of the
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* vertices in a vertex buffer.
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*
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* Any un-submitted attribute changes are automatically submitted before
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* drawing.
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*/
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void
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cogl_vertex_buffer_draw (CoglHandle handle,
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GLenum mode,
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GLint first,
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GLsizei count);
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/**
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* CoglIndicesType:
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* @COGL_INDICES_TYPE_UNSIGNED_BYTE: Your indices are unsigned bytes
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* @COGL_INDICES_TYPE_UNSIGNED_SHORT: Your indices are unsigned shorts
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* @COGL_INDICES_TYPE_UNSIGNED_INT: You indices are unsigned integers
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*
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* You should aim to use the smallest data type that gives you enough
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* range, since it reduces the size of your index array and can help
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* reduce the demand on memory bandwidth.
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*/
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typedef enum _CoglIndicesType
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{
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COGL_INDICES_TYPE_UNSIGNED_BYTE,
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COGL_INDICES_TYPE_UNSIGNED_SHORT,
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COGL_INDICES_TYPE_UNSIGNED_INT
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} CoglIndicesType;
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/**
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* cogl_vertex_buffer_add_indices:
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* @handle: A vertex buffer handle
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* @id: Any unique number. It's used to identify the indices when you later
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* call cogl_vertex_buffer_draw_elements()
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* @min_index: Specifies the minimum vertex index contained in indices
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* @max_index: Specifies the maximum vertex index contained in indices
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* @indices_type: a #CoglIndicesType specifying the data type used for
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* the indices.
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* @indices_array: Specifies the address of your array of indices
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* @indices_len: The number of indices in indices_array
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*
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* Depending on how much geometry you are submitting it can be worthwhile
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* optimizing the number of redundant vertices you submit. Using an index
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* array allows you to reference vertices multiple times, for example
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* during triangle strips.
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*
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* You should aim to use the COGL_INDICES_TYPE_UNSIGNED_SHORT when possible
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* and correctly reflect the range of index values in the {min,max}_index
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* arguments. This allows Cogl to optimize the internal storage used for
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* the indices and reduce the demand for memory bandwidth.
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*/
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void
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cogl_vertex_buffer_add_indices (CoglHandle handle,
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int id,
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unsigned int min_index,
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unsigned int max_index,
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CoglIndicesType indices_type,
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const void *indices_array,
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size_t indices_len);
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/**
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* cogl_vertex_buffer_draw_elements:
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* @handle: A vertex buffer handle
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* @mode: Specifies how the vertices should be interpreted, and should be
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* a valid GL primitive type:
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* <itemizedlist>
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* <listitem>GL_POINTS</listitem>
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* <listitem>GL_LINE_STRIP</listitem>
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* <listitem>GL_LINE_LOOP</listitem>
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* <listitem>GL_LINES</listitem>
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* <listitem>GL_TRIANGLE_STRIP</listitem>
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* <listitem>GL_TRIANGLE_FAN</listitem>
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* <listitem>GL_TRIANGLES</listitem>
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* </itemizedlist>
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* @indices_id: The identifier for a an array of indices previously added to
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* the given Cogl vertex buffer using
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* cogl_vertex_buffer_add_indices().
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* @indices_offset: An offset into named indices. The offset marks the first
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* index to use for drawing.
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* @count: Specifies the number of vertices you want to draw.
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*
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* This function lets you use an array of indices to specify the vertices
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* within your vertex buffer that you want to draw. The indices themselves
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* are given by calling cogl_vertex_buffer_add_indices ()
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*
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* Any un-submitted attribute changes are automatically submitted before
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* drawing.
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*/
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void
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cogl_vertex_buffer_draw_elements (CoglHandle handle,
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GLenum mode,
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int indices_id,
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unsigned int indices_offset,
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unsigned int count);
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/**
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* cogl_vertex_buffer_ref:
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* @handle: a @CoglHandle.
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*
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* Increment the reference count for a vertex buffer
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*
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* Returns: the @handle.
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*/
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CoglHandle
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cogl_vertex_buffer_ref (CoglHandle handle);
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/**
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* cogl_vertex_buffer_unref:
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* @handle: a @CoglHandle.
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*
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* Decrement the reference count for a vertex buffer
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*/
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void
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cogl_vertex_buffer_unref (CoglHandle handle);
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G_END_DECLS
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#endif /* __COGL_VERTEX_BUFFER_H__ */
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