mutter/clutter/cogl/cogl-vertex-buffer.h

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/*
* Cogl.
*
* An OpenGL/GLES Abstraction/Utility Layer
*
* Vertex Buffer API: Handle extensible arrays of vertex attributes
*
* Copyright (C) 2008 Intel Corporation.
*
* Authored by: Robert Bragg <robert@linux.intel.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_VERTEX_BUFFER_H__
#define __COGL_VERTEX_BUFFER_H__
#include <glib.h>
#include <cogl/cogl-types.h>
G_BEGIN_DECLS
/**
* SECTION:cogl-vertex-buffer
* @short_description: An API for submitting extensible arrays of vertex
* attributes to be mapped into the GPU for fast
* drawing.
*
* For example to describe a textured triangle, you could create a new cogl
* vertex buffer with 3 vertices, and then you might add 2 attributes for each
* vertex:
* <orderedlist>
* <listitem>
* a "gl_Position" describing the (x,y,z) position for each vertex.
* </listitem>
* <listitem>
* a "gl_MultiTexCoord0" describing the (tx,ty) texture coordinates for each
* vertex.
* </listitem>
* </orderedlist>
*
* The Vertex Buffer API is designed to be a fairly raw mechanism for
* developers to be able to submit geometry to Cogl in a format that can be
* directly consumed by an OpenGL driver and mapped into your GPU for fast
* re-use. It is designed to avoid repeated validation of the attributes by the
* driver; to minimize transport costs (e.g. considering indirect GLX
* use-cases) and to potentially avoid repeated format conversions when
* attributes are supplied in a format that is not natively supported by the
* GPU.
*
* Although this API does allow you to modify attributes after they have been
* submitted to the GPU you should be aware that modification is not that
* cheap, since it implies validating the new data and potentially the
* OpenGL driver will need to reformat it for the GPU.
*
* If at all possible think of tricks that let you re-use static attributes,
* and if you do need to repeatedly update attributes (e.g. for some kind of
* morphing geometry) then only update and re-submit the specific attributes
* that have changed.
*/
/**
* cogl_vertex_buffer_new:
* @n_vertices: The number of vertices that your attributes will correspond to.
*
* This creates a Cogl handle for a new vertex buffer that you can then start
* to add attributes too.
*/
CoglHandle
cogl_vertex_buffer_new (guint n_vertices);
/**
* cogl_vertex_buffer_get_n_vertices:
* @handle: A vertex buffer handle
*
* This returns the number of vertices that @handle represents
*/
guint
cogl_vertex_buffer_get_n_vertices (CoglHandle handle);
/**
* cogl_vertex_buffer_add:
* @handle: A vertex buffer handle
* @attribute_name: The name of your attribute. It should be a valid GLSL
* variable name and standard attribute types must use one
* of following built-in names: (Note: they correspond to the
* built-in names of GLSL)
* <itemizedlist>
* <listitem>"gl_Color"</listitem>
* <listitem>"gl_Normal"</listitem>
* <listitem>"gl_MultiTexCoord0, gl_MultiTexCoord1, ..."</listitem>
* <listitem>"gl_Vertex"</listitem>
* </itemizedlist>
* To support adding multiple variations of the same attribute
* the name can have a detail component, E.g.
* "gl_Color::active" or "gl_Color::inactive"
* @n_components: The number of components per attribute and must be 1,2,3 or 4
* @gl_type: Specifies the data type of each component (GL_BYTE, GL_UNSIGNED_BYTE,
* GL_SHORT, GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT or GL_FLOAT)
* @normalized: If GL_TRUE, this specifies that values stored in an integer
* format should be mapped into the range [-1.0, 1.0] or [0.1, 1.0]
* for unsigned values. If GL_FALSE they are converted to floats
* directly.
* @stride: This specifies the number of bytes from the start of one attribute
* value to the start of the next value (for the same attribute). So
* for example with a position interleved with color like this:
* XYRGBAXYRGBAXYRGBA, then if each letter represents a byte, the
* stride for both attributes is 6. The special value 0 means the
* values are stored sequentially in memory.
* @pointer: This addresses the first attribute in the vertex array. (This
* must remain valid until you either call
* cogl_vertex_buffer_submit() or issue a draw call.)
*
* This function lets you add an attribute to a buffer. You either use one
* of the built-in names such as "gl_Vertex", or "gl_MultiTexCoord0" to add
* standard attributes, like positions, colors and normals or you can add
* custom attributes for use in shaders.
*
* The number of vertices declared when calling cogl_vertex_buffer_new()
* determines how many attribute values will be read from the supplied pointer.
*
* The data for your attribute isn't copied anywhere until you call
* cogl_vertex_buffer_submit(), (or issue a draw call which automatically
* submits pending attribute changes) so the supplied pointer must remain
* valid until then. If you are updating an existing attribute (done by
* re-adding it) then you still need to re-call cogl_vertex_buffer_submit() to
* commit the changes to the GPU. (Be carefull to minimize the number of calls
* to cogl_vertex_buffer_submit though.)
*
* Note: If you are interleving attributes it is assumed that each interleaved
* attribute starts no farther than +- stride bytes from the other attributes
* it is interleved with. I.e. this is ok:
* <programlisting>
* |-0-0-0-0-0-0-0-0-0-0|
* </programlisting>
* This is not ok:
* <programlisting>
* |- - - - -0-0-0-0-0-0 0 0 0 0|
* </programlisting>
* (Though you can have multiple groups of interleved attributes)
*/
void
cogl_vertex_buffer_add (CoglHandle handle,
const char *attribute_name,
guint8 n_components,
GLenum gl_type,
gboolean normalized,
guint16 stride,
const void *pointer);
/**
* cogl_vertex_buffer_delete:
* @handle: A vertex buffer handle
* @attribute_name: The name of a previously added attribute
*
* This function deletes an attribute from a buffer. You will need to
* call cogl_vertex_buffer_submit() or issue a draw call to commit this
* change to the GPU.
*/
void
cogl_vertex_buffer_delete (CoglHandle handle,
const char *attribute_name);
/**
* cogl_vertex_buffer_submit:
* @handle: A vertex buffer handle
*
* This function submits all the user added attributes to the GPU; once
* submitted the attributes can be used for drawing.
*
* You should aim to minimize calls to this function since it implies
* validating your data; it potentially incurs a transport cost (especially if
* you are using GLX indirect rendering) and potentially a format conversion
* cost if the GPU doesn't natively support any of the given attribute formats.
*/
void
cogl_vertex_buffer_submit (CoglHandle handle);
/**
* cogl_vertex_buffer_disable:
* @handle: A vertex buffer handle
* @attribute_name: The name of the attribute you want to disable
*
* This function disables a previosuly added attribute.
*
* Since it can be costly to add and remove new attributes to buffers; to make
* individual buffers more reuseable it is possible to enable and disable
* attributes before using a buffer for drawing.
*
* You don't need to call cogl_vertex_buffer_submit() after using this function.
*/
void
cogl_vertex_buffer_disable (CoglHandle handle,
const char *attribute_name);
/**
* cogl_vertex_buffer_enable:
* @handle: A vertex buffer handle
* @attribute_name: The name of the attribute you want to enable
*
* This function enables a previosuly disabled attribute.
*
* Since it can be costly to add and remove new attributes to buffers; to make
* individual buffers more reuseable it is possible to enable and disable
* attributes before using a buffer for drawing.
*
* You don't need to call cogl_vertex_buffer_submit() after using this function
*/
void
cogl_vertex_buffer_enable (CoglHandle handle,
const char *attribute_name);
/**
* cogl_vertex_buffer_draw:
* @handle: A vertex buffer handle
* @mode: Specifies how the vertices should be interpreted, and should be
* a valid GL primitive type:
* <itemizedlist>
* <listitem>GL_POINTS</listitem>
* <listitem>GL_LINE_STRIP</listitem>
* <listitem>GL_LINE_LOOP</listitem>
* <listitem>GL_LINES</listitem>
* <listitem>GL_TRIANGLE_STRIP</listitem>
* <listitem>GL_TRIANGLE_FAN</listitem>
* <listitem>GL_TRIANGLES</listitem>
* </itemizedlist>
* (Note: only types available in GLES are listed)
* @first: Specifies the index of the first vertex you want to draw with
* @count: Specifies the number of vertices you want to draw.
*
* This function lets you draw geometry using all or a subset of the
* vertices in a vertex buffer.
*
* Any un-submitted attribute changes are automatically submitted before
* drawing.
*/
void
cogl_vertex_buffer_draw (CoglHandle handle,
GLenum mode,
GLint first,
GLsizei count);
/**
* cogl_vertex_buffer_draw_elements:
* @handle: A vertex buffer handle
* @mode: Specifies how the vertices should be interpreted, and should be
* a valid GL primitive type:
* <itemizedlist>
* <listitem>GL_POINTS</listitem>
* <listitem>GL_LINE_STRIP</listitem>
* <listitem>GL_LINE_LOOP</listitem>
* <listitem>GL_LINES</listitem>
* <listitem>GL_TRIANGLE_STRIP</listitem>
* <listitem>GL_TRIANGLE_FAN</listitem>
* <listitem>GL_TRIANGLES</listitem>
* </itemizedlist>
* (Note: only types available in GLES are listed)
* @min_index: Specifies the minimum vertex index contained in indices
* @max_index: Specifies the maximum vertex index contained in indices
* @count: Specifies the number of vertices you want to draw.
* @indices_type: Specifies the data type used for the indices, and must be
* one of:
* <itemizedlist>
* <listitem>GL_UNSIGNED_BYTE</listitem>
* <listitem>GL_UNSIGNED_SHORT</listitem>
* <listitem>GL_UNSIGNED_INT</listitem>
* </itemizedlist>
* @indices: Specifies the address of your array of indices
*
* This function lets you use an array of indices to specify the vertices
* within your vertex buffer that you want to draw.
*
* Any un-submitted attribute changes are automatically submitted before
* drawing.
*/
void
cogl_vertex_buffer_draw_elements (CoglHandle handle,
GLenum mode,
GLuint min_index,
GLuint max_index,
GLsizei count,
GLenum indices_type,
const GLvoid *indices);
/**
* cogl_vertex_buffer_ref:
* @handle: a @CoglHandle.
*
* Increment the reference count for a vertex buffer
*
* Returns: the @handle.
*/
CoglHandle
cogl_vertex_buffer_ref (CoglHandle handle);
/**
* cogl_vertex_buffer_unref:
* @handle: a @CoglHandle.
*
* Decrement the reference count for a vertex buffer
*/
void
cogl_vertex_buffer_unref (CoglHandle handle);
G_END_DECLS
#endif /* __COGL_VERTEX_BUFFER_H__ */