/* * 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 * * 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 . */ #if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION) #error "Only can be included directly." #endif #ifndef __COGL_VERTEX_BUFFER_H__ #define __COGL_VERTEX_BUFFER_H__ #include #include 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: * * * a "gl_Position" describing the (x,y,z) position for each vertex. * * * a "gl_MultiTexCoord0" describing the (tx,ty) texture coordinates for each * vertex. * * * * 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) * * "gl_Color" * "gl_Normal" * "gl_MultiTexCoord0, gl_MultiTexCoord1, ..." * "gl_Vertex" * * 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 "glMultiTexCoord0" 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: * * |-0-0-0-0-0-0-0-0-0-0| * * This is not ok: * * |- - - - -0-0-0-0-0-0 0 0 0 0| * * (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: * * GL_POINTS * GL_LINE_STRIP * GL_LINE_LOOP * GL_LINES * GL_TRIANGLE_STRIP * GL_TRIANGLE_FAN * GL_TRIANGLES * * (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_range_elements: * @handle: A vertex buffer handle * @mode: Specifies how the vertices should be interpreted, and should be * a valid GL primitive type: * * GL_POINTS * GL_LINE_STRIP * GL_LINE_LOOP * GL_LINES * GL_TRIANGLE_STRIP * GL_TRIANGLE_FAN * GL_TRIANGLES * * (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: * * GL_UNSIGNED_BYTE * GL_UNSIGNED_SHORT * GL_UNSIGNED_INT * * @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__ */