glx-multithread-texture: Avoid front-buffer rendering.

[piglit.git] / tests / util / piglit-vbo.cpp

/*
 * Copyright © 2011, 2016 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/**
 * \file piglit-vbo.cpp
 *
 * This file adds the facility for specifying vertex data to piglit
 * tests using a columnar text format, for example:
 *
 *   \verbatim
 *   vertex/double/vec3 foo/uint/uint   bar[0]/int/int  bar[1]/int/int
 *   0.0 0.0 0.0        10              0               0       # comment
 *   0.0 1.0 0.0         5              1               1
 *   1.0 1.0 0.0         0              0               1
 *   \endverbatim
 *
 * The format consists of a row of column headers followed by any
 * number of rows of data.  Each column header has the form
 * "ATTRNAME[ARRAY_INDEX]/GL_TYPE/GLSL_TYPE/MATRIX_COLUMN", where
 * ATTRNAME is the name of the vertex attribute to be bound to this
 * column, ARRAY_INDEX is the index, GL_TYPE is the GL type of data
 * that follows ("half", "float", "double", "byte", "ubyte", "short",
 * "ushort", "int" or "uint"), GLSL_TYPE is the GLSL type of the data
 * ("int", "uint", "float", "double", "ivec"*, "uvec"*, "vec"*,
 * "dvec"*, "mat"*, "dmat"*) and MATRIX_COLUMN is the column number of
 * the data in case of being a matrix. [ARRAY_INDEX] is optional and
 * needs to be specified only in case of array
 * attributes. MATRIX_COLUMN doesn't need to be specified if it is not
 * a matrix column as in the example before. So another example, if
 * you want to specify the data of a mat2x3:
 *
 *   \verbatim
 *   foomatrix/float/mat2x3/0   foomatrix/float/mat2x3/1
 *   0.0 1.0 2.0                3.0 4.0 5.0
 *   6.0 7.0 8.0                9.0 10.0 11.0
 *   \endverbatim
 *
 * The same example, using the deprecated but compatible syntax would
 * be:
 *
 *   \verbatim
 *   foomatrix/float/3/0        foomatrix/float/3/1
 *   0.0 1.0 2.0                3.0 4.0 5.0
 *   6.0 7.0 8.0                9.0 10.0 11.0
 *   \endverbatim
 *
 * The data follows the column headers in space-separated form.  "#"
 * can be used for comments, as in shell scripts.
 *
 * To process textual vertex data, call the function
 * setup_vbo_from_text(), passing the int identifying the linked
 * program, and the string containing the vertex data.  The return
 * value is the number of rows of vertex data found.
 *
 * If an error occurs, setup_vbo_from_text() will print out a
 * description of the error and exit with PIGLIT_FAIL.
 *
 * For the first example above, the call to setup_vbo_from_text() is
 * roughly equivalent to the following GL operations:
 *
 * \code
 * struct vertex_attributes {
 *         GLfloat vertex[3];
 *         GLuint foo;
 *         GLint bar[2];
 * } vertex_data[] = {
 *         { { 0.0, 0.0, 0.0 }, 10, { 0, 0 } },
 *         { { 0.0, 1.0, 0.0 },  5, { 1, 1 } },
 *         { { 1.0, 1.0, 0.0 },  0, { 0, 1 } }
 * };
 * size_t stride = sizeof(vertex_data[0]);
 * GLint vertex_index = glGetAttribLocation(prog, "vertex");
 * GLint foo_index = glGetAttribLocation(prog, "foo");
 * GLint bar_index = glGetAttribLocation(prog, "bar");
 * GLuint buffer_handle;
 * glGenBuffers(1, &buffer_handle);
 * glBindBuffer(GL_ARRAY_BUFFER, buffer_handle);
 * glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_data), &vertex_data,
 *              GL_STATIC_DRAW);
 * glVertexAttribPointer(vertex_index, 3, GL_FLOAT, GL_FALSE, stride,
 *                       (void *) offsetof(vertex_attributes, vertex));
 * glVertexAttribIPointer(foo_index, 3, GL_UNSIGNED_INT, stride,
 *                        (void *) offsetof(vertex_attributes, foo));
 * glVertexAttribIPointer(bar_index, 3, GL_INT, stride,
 *                        (void *) offsetof(vertex_attributes, bar));
 * glEnableVertexAttribArray(vertex_index);
 * glEnableVertexAttribArray(foo_index);
 * glEnableVertexAttribArray(bar_index);
 * \endcode
 *
 * Which could correspond to a vertex shader of this type:
 *
 * \code
 * in vec3 vertex;
 * in uint foo;
 * in int bar[2];
 *
 * void main()
 * {
 *      if (bar[0] + bar[1] == foo) {
 *              gl_Position = vec4(vertex, 1.0);
 *      } else {
 *              gl_Position = vec4(1.0, vertex);
 *      }
 * }
 * \endcode
 */

#include <string>
#include <vector>
#include <errno.h>
#include <limits.h>
#include <ctype.h>
#include <stdlib.h>

#include "piglit-util.h"
#include "piglit-util-gl.h"
#include "piglit-vbo.h"

/**
 * Convert a type name string to a GLenum.
 */
static bool
decode_type(const char *type,
            GLenum *gl_type, size_t *gl_type_size, GLenum *glsl_type)
{
        assert(type);
        assert(gl_type);
        assert(gl_type_size);

        static struct type_table_entry {
                const char *type; /* NULL means end of table */
                GLenum gl_type;
                size_t gl_type_size;
                GLenum glsl_type;
        } const type_table[] = {
                { "byte",    GL_BYTE,           1,      GL_INT          },
                { "ubyte",   GL_UNSIGNED_BYTE,  1,      GL_UNSIGNED_INT },
                { "short",   GL_SHORT,          2,      GL_INT          },
                { "ushort",  GL_UNSIGNED_SHORT, 2,      GL_UNSIGNED_INT },
                { "int",     GL_INT,            4,      GL_INT          },
                { "uint",    GL_UNSIGNED_INT,   4,      GL_UNSIGNED_INT },
                { "half",    GL_HALF_FLOAT,     2,      GL_FLOAT        },
                { "float",   GL_FLOAT,          4,      GL_FLOAT        },
                { "double",  GL_DOUBLE,         8,      GL_DOUBLE       },
                { NULL,      0,                 0,      0               },
        };


        for (int i = 0; type_table[i].type; ++i) {
                if (0 == strcmp(type, type_table[i].type)) {
                        *gl_type = type_table[i].gl_type;
                        *gl_type_size = type_table[i].gl_type_size;
                        if (glsl_type)
                                *glsl_type = type_table[i].glsl_type;
                        return true;
                }
        }

        return false;
}


/**
 * Convert a GLSL type name string to its basic GLenum type.
 */
static bool
decode_glsl_type(const char *type,
                 GLenum *glsl_type, size_t *rows, size_t *cols, char **endptr)
{
        assert(glsl_type);
        assert(rows);
        assert(cols);
        assert(endptr);

        if (isdigit(type[0])) {
                *rows = strtoul(type, endptr, 10);
                *cols = 1;
                *glsl_type = 0;
                return true;
        }

        static struct type_table_entry {
                const char *type; /* NULL means end of table */
                GLenum glsl_type;
        } const type_table[] = {
                { "int",     GL_INT            },
                { "uint",    GL_UNSIGNED_INT   },
                { "float",   GL_FLOAT          },
                { "double",  GL_DOUBLE         },
                { "ivec",    GL_INT            },
                { "uvec",    GL_UNSIGNED_INT   },
                { "vec",     GL_FLOAT          },
                { "dvec",    GL_DOUBLE         },
                { "mat",     GL_FLOAT          },
                { "dmat",    GL_DOUBLE         },
                { NULL,      0                 }
        };


        for (int i = 0; type_table[i].type; ++i) {
                const size_t type_len = strlen(type_table[i].type);
                if (0 == strncmp(type, type_table[i].type, type_len)) {
                        *endptr = const_cast<char *>(&type[type_len]);

                        /* In case of vectors or matrices, let's
                         * calculate rows and columns.
                         */
                        if (i > 3) {
                                if (!isdigit(**endptr))
                                        goto cleanup;
                                *rows = **endptr - '0';
                                ++*endptr;

                                /* In case of matrices, let's
                                 * calculate the rows.
                                 */
                                if (i > 7) {
                                        *cols = *rows;
                                        if (**endptr == 'x') {
                                                if (!isdigit(*(++*endptr)))
                                                        goto cleanup;
                                                *rows = **endptr - '0';
                                                ++*endptr;
                                        }
                                } else {
                                        *cols = 1;
                                }
                        } else {
                                *rows = 1;
                                *cols = 1;
                        }
                        *glsl_type = type_table[i].glsl_type;
                        return true;
                }
        }

cleanup:
        *glsl_type = 0;
        *endptr = const_cast<char *>(type);
        return false;
}


/**
 * Description of a vertex attribute, built from its column header
 */
class vertex_attrib_description
{
public:
        vertex_attrib_description(GLuint prog, const char *text);
        bool parse_datum(const char **text, void *data) const;
        void setup(size_t *offset, size_t stride) const;

        /**
         * GL data type of this attribute.
         */
        GLenum data_type;

        /**
         * Size of the GL data type of this attribute.
         */
        size_t data_type_size;

        /**
         * GLSL data type of this attribute.
         */
        GLenum glsl_data_type;

        /**
         * Index of the array for this attribute.
         */
        size_t array_index;

        /**
         * Number of columns of the GLSL data type of this attribute.
         */
        size_t cols;

        /**
         * Number of rows of the GLSL data type of this attribute.
         */
        size_t rows;

        /**
         * Index of the matrix column for this attribute.
         */
        size_t matrix_index;

        /**
         * Index of this vertex attribute in the linked program.
         */
        GLuint index;
};

static bool
get_attrib_location(GLuint prog,
                    const std::string &name,
                    GLuint *index)
{
        errno = 0;

        char *end;
        unsigned long ul = strtoul(name.c_str(), &end, 10);

        if (errno == 0 && *end == '\0' && ul <= UINT_MAX) {
                *index = ul;
                return true;
        }

        GLint attrib_location = glGetAttribLocation(prog, name.c_str());
        if (attrib_location == -1)
                return false;

        *index = attrib_location;

        return true;
}

/**
 * Build a vertex_attrib_description from a column header, by looking
 * up the vertex attribute in the linked program and interpreting the
 * type, dimensions and mattrix_column parts of the header.
 *
 * If there is a parse failure, print a description of the problem and
 * then exit with PIGLIT_FAIL.
 */
vertex_attrib_description::vertex_attrib_description(GLuint prog,
                                                     const char *text)
{
        /* Split the column header into
         * name[array_index]/type/dimensions/matrix_column fields.
         */
        const char *first_slash = strchr(text, '/');
        if (first_slash == NULL) {
                printf("Column headers must be in the form"
                       " name[array_index]/type/dimensions/matrix_column.\n"
                       "Note: [array_index] and matrix_column are optional.\n"
                       "Got: %s\n",
                       text);
                piglit_report_result(PIGLIT_FAIL);
        }

        std::string name(text, first_slash);

        /* If the attrib is an array, strip the index */
        if (name[name.size() - 1] == ']') {
                std::string::size_type n = name.find('[');
                if (n == std::string::npos) {
                        printf("Column header looked like an array"
                               " but couldn't parse it.\n"
                               "Got: %s\n",
                               text);
                        piglit_report_result(PIGLIT_FAIL);
                } else {
                        this->array_index = strtoul(name.substr(n + 1).c_str(), NULL, 0);
                        name.resize(n);
                }
        } else {
                this->array_index = 0;
        }

        const char *second_slash = strchr(first_slash + 1, '/');
        if (second_slash == NULL) {
                printf("Column headers must be in the form"
                       " name[array_index]/type/dimensions/matrix_column.\n"
                       "Note: [array_index] and matrix_column are optional.\n"
                       "Got: %s\n",
                       text);
                piglit_report_result(PIGLIT_FAIL);
        }

        char *endptr;
        if (!decode_glsl_type(second_slash + 1,
                              &this->glsl_data_type,
                              &this->rows, &this->cols,
                              &endptr)) {
                printf("Unrecognized GLSL type: %s\n", second_slash + 1);
                piglit_report_result(PIGLIT_FAIL);
        }

        std::string type_str(first_slash + 1, second_slash);
        GLenum *glsl_data_type = this->glsl_data_type ? 0
                : &this->glsl_data_type;

        if (!decode_type(type_str.c_str(),
                         &this->data_type, &this->data_type_size,
                         glsl_data_type)) {
                printf("Unrecognized GL type: %s\n", type_str.c_str());
                piglit_report_result(PIGLIT_FAIL);
        }

        if (*endptr != '\0') {
                const char *third_slash = strchr(second_slash + 1, '/');
                this->matrix_index = strtoul(third_slash + 1, &endptr, 10);

                if (this->matrix_index > 3) {
                        printf("Matrix column index must be between 0 and 3.  Got: %lu\n",
                                (unsigned long) this->matrix_index);
                        piglit_report_result(PIGLIT_FAIL);
                }

                if (*endptr != '\0') {
                        printf("Column headers must be in the form"
                               " name[array_index]/type/dimensions/matrix_column.\n"
                               "Note: [array_index] and matrix_column are optional.\n"
                               "Got: %s\n",
                               text);
                        piglit_report_result(PIGLIT_FAIL);
                }
        } else {
                this->matrix_index = 0;
        }

        if (!get_attrib_location(prog, name, &this->index)) {
                printf("Unexpected vbo column name.  Got: %s\n", name.c_str());
                piglit_report_result(PIGLIT_FAIL);
        }
        /* If the type is integral, verify that integer vertex
         * attribute support is present.  Note: we treat it as a FAIL
         * if support is not present, because it's up to the test to
         * either (a) not require integer vertex attribute support, or
         * (b) skip itself if integer vertex attribute support is not
         * present.
         */
        if (this->glsl_data_type != GL_FLOAT &&
            (piglit_is_gles() ||
            (piglit_get_gl_version() < 30 &&
                !piglit_is_extension_supported("GL_EXT_gpu_shader4")))) {
                printf("Test uses glVertexAttribIPointer(),"
                       " which is unsupported.\n");
                piglit_report_result(PIGLIT_FAIL);
        }

        if (this->rows < 1 || this->rows > 4) {
                printf("Rows must be between 1 and 4.  Got: %lu\n",
                       (unsigned long) this->rows);
                piglit_report_result(PIGLIT_FAIL);
        }

        if (this->cols < 1 || this->cols > 4) {
                printf("Columns must be between 1 and 4.  Got: %lu\n",
                       (unsigned long) this->cols);
                piglit_report_result(PIGLIT_FAIL);
        }
}


/**
 * Parse a single number (floating point or integral) from one of the
 * data rows, and store it in the location pointed to by \c data.
 * Update \c text to point to the next character of input.
 *
 * If there is a parse failure, print a description of the problem and
 * then return false.  Otherwise return true.
 */
bool
vertex_attrib_description::parse_datum(const char **text, void *data) const
{
        char *endptr;
        errno = 0;
        switch (this->data_type) {
        case GL_HALF_FLOAT: {
                unsigned short value = strtohf_hex(*text, &endptr);
                if (errno == ERANGE) {
                        printf("Could not parse as half float\n");
                        return false;
                }
                *((GLhalf *) data) = value;
                break;
        }
        case GL_FLOAT: {
                float value = strtof_hex(*text, &endptr);
                if (errno == ERANGE) {
                        printf("Could not parse as float\n");
                        return false;
                }
                *((GLfloat *) data) = value;
                break;
        }
        case GL_DOUBLE: {
                double value = strtod_hex(*text, &endptr);
                if (errno == ERANGE) {
                        printf("Could not parse as double\n");
                        return false;
                }
                *((GLdouble *) data) = value;
                break;
        }
        case GL_BYTE: {
                long value = strtol_hex(*text, &endptr);
                if (errno == ERANGE || value < SCHAR_MIN || value > SCHAR_MAX) {
                        printf("Could not parse as signed byte\n");
                        return false;
                }
                *((GLbyte *) data) = (GLbyte) value;
                break;
        }
        case GL_UNSIGNED_BYTE: {
                unsigned long value = strtoul(*text, &endptr, 0);
                if (errno == ERANGE || value > UCHAR_MAX) {
                        printf("Could not parse as unsigned byte\n");
                        return false;
                }
                *((GLubyte *) data) = (GLubyte) value;
                break;
        }
        case GL_SHORT: {
                long value = strtol_hex(*text, &endptr);
                if (errno == ERANGE || value < SHRT_MIN || value > SHRT_MAX) {
                        printf("Could not parse as signed short\n");
                        return false;
                }
                *((GLshort *) data) = (GLshort) value;
                break;
        }
        case GL_UNSIGNED_SHORT: {
                unsigned long value = strtoul(*text, &endptr, 0);
                if (errno == ERANGE || value > USHRT_MAX) {
                        printf("Could not parse as unsigned short\n");
                        return false;
                }
                *((GLushort *) data) = (GLushort) value;
                break;
        }
        case GL_INT: {
                long value = strtol_hex(*text, &endptr);
                if (errno == ERANGE) {
                        printf("Could not parse as signed integer\n");
                        return false;
                }
                *((GLint *) data) = (GLint) value;
                break;
        }
        case GL_UNSIGNED_INT: {
                unsigned long value = strtoul(*text, &endptr, 0);
                if (errno == ERANGE) {
                        printf("Could not parse as unsigned integer\n");
                        return false;
                }
                *((GLuint *) data) = (GLuint) value;
                break;
        }
        default:
                assert(!"Unexpected data type");
                endptr = NULL;
                break;
        }
        *text = endptr;
        return true;
}


/**
 * Execute the necessary GL calls to bind this attribute to its data.
 */
void
vertex_attrib_description::setup(size_t *offset, size_t stride) const
{
        GLuint actual_index = this->index + this->matrix_index
                + this->array_index * this->cols;
        switch (this->glsl_data_type) {
        case GL_FLOAT:
                glVertexAttribPointer(actual_index, this->rows,
                                      this->data_type, GL_FALSE, stride,
                                      (void *) *offset);
                break;
        case GL_DOUBLE:
                if (piglit_is_gles()
                    || !piglit_is_extension_supported("GL_ARB_vertex_attrib_64bit")) {
                        fprintf(stderr,"vertex_attrib_description fail. no 64-bit float support\n");
                        return;
                }
                if (this->data_type != GL_DOUBLE) {
                        fprintf(stderr,"vertex_attrib_description fail. the GL"
                                " type must be 'GL_DOUBLE' and it is '%s'\n",
                                piglit_get_prim_name(this->data_type));
                        return;
                }
                glVertexAttribLPointer(actual_index, this->rows,
                                       this->data_type, stride,
                                       (void *) *offset);
                break;
        default:
                if (piglit_is_gles() && piglit_get_gl_version() < 30) {
                        fprintf(stderr,"vertex_attrib_description fail. no int support\n");
                        return;
                }
                switch (this->data_type) {
                case GL_BYTE:
                case GL_UNSIGNED_BYTE:
                case GL_SHORT:
                case GL_UNSIGNED_SHORT:
                case GL_INT:
                case GL_UNSIGNED_INT:
                        break;
                default:
                        fprintf(stderr,"vertex_attrib_description fail. the GL"
                                " type '%s' is incompatible\n",
                                piglit_get_prim_name(this->data_type));
                        return;
                }
                glVertexAttribIPointer(actual_index, this->rows,
                                       this->data_type, stride,
                                       (void *) *offset);
                break;
        }
        glEnableVertexAttribArray(actual_index);
        *offset += this->rows * this->data_type_size;
}


/**
 * Data structure containing all of the data parsed from the text
 * input, as well as the methods that parse it and convert it to GL
 * calls.
 */
class vbo_data
{
public:
        vbo_data(std::string const &text, GLuint prog);
        size_t setup() const;

private:
        void parse_header_line(const std::string &line, GLuint prog);
        void parse_data_line(const std::string &line, unsigned int line_num);
        void parse_line(std::string line, unsigned int line_num, GLuint prog);

        /**
         * True if the header line has already been parsed.
         */
        bool header_seen;

        /**
         * Description of each attribute.
         */
        std::vector<vertex_attrib_description> attribs;

        /**
         * Raw data buffer containing parsed numbers.
         */
        std::vector<char> raw_data;

        /**
         * Number of bytes in each row of raw_data.
         */
        size_t stride;

        /**
         * Number of rows in raw_data.
         */
        size_t num_rows;
};



static bool
is_blank_line(const std::string &line)
{
        for (size_t i = 0; i < line.size(); ++i) {
                if (!isspace(line[i]))
                        return false;
        }
        return true;
}


/**
 * Populate this->attribs and compute this->stride based on column
 * headers.
 *
 * If there is a parse failure, print a description of the problem and
 * then exit with PIGLIT_FAIL.
 */
void
vbo_data::parse_header_line(const std::string &line, GLuint prog)
{
        size_t pos = 0;
        this->stride = 0;
        while (pos < line.size()) {
                if (isspace(line[pos])) {
                        ++pos;
                } else {
                        size_t column_header_end = pos;
                        while (column_header_end < line.size() &&
                               !isspace(line[column_header_end]))
                                ++column_header_end;
                        std::string column_header = line.substr(
                                pos, column_header_end - pos);
                        vertex_attrib_description desc(
                                prog, column_header.c_str());
                        attribs.push_back(desc);
                        this->stride += desc.rows * desc.data_type_size;
                        pos = column_header_end + 1;
                }
        }
}


/**
 * Convert a data row into binary form and append it to this->raw_data.
 *
 * If there is a parse failure, print a description of the problem and
 * then exit with PIGLIT_FAIL.
 */
void
vbo_data::parse_data_line(const std::string &line, unsigned int line_num)
{
        /* Allocate space in raw_data for this line */
        size_t old_size = this->raw_data.size();
        this->raw_data.resize(old_size + this->stride);
        char *data_ptr = &this->raw_data[old_size];

        const char *line_ptr = line.c_str();
        for (size_t i = 0; i < this->attribs.size(); ++i) {
                for (size_t j = 0; j < this->attribs[i].rows; ++j) {
                        if (!this->attribs[i].parse_datum(&line_ptr,
                                                          data_ptr)) {
                                printf("At line %u of [vertex data] section\n",
                                       line_num);
                                printf("Offending text: %s\n", line_ptr);
                                piglit_report_result(PIGLIT_FAIL);
                        }
                        data_ptr += this->attribs[i].data_type_size;
                }
        }

        ++this->num_rows;
}


/**
 * Parse a line of input text.
 *
 * If there is a parse failure, print a description of the problem and
 * then exit with PIGLIT_FAIL.
 */
void
vbo_data::parse_line(std::string line, unsigned int line_num, GLuint prog)
{
        /* Ignore end-of-line comments */
        line = line.substr(0, line.find('#'));

        /* Ignore blank or comment-only lines */
        if (is_blank_line(line))
                return;

        if (!this->header_seen) {
                this->header_seen = true;
                parse_header_line(line, prog);
        } else {
                parse_data_line(line, line_num);
        }
}


/**
 * Parse the input but don't execute any GL commands.
 *
 * If there is a parse failure, print a description of the problem and
 * then exit with PIGLIT_FAIL.
 */
vbo_data::vbo_data(const std::string &text, GLuint prog)
        : header_seen(false), stride(0), num_rows(0)
{
        unsigned int line_num = 1;

        size_t pos = 0;
        while (pos < text.size()) {
                size_t end_of_line = text.find('\n', pos);
                if (end_of_line == std::string::npos)
                        end_of_line = text.size();
                parse_line(text.substr(pos, end_of_line), line_num++, prog);
                pos = end_of_line + 1;
        }
}


/**
 * Execute the necessary GL commands to set up the vertex data passed
 * to the constructor.
 */
size_t
vbo_data::setup() const
{
        GLuint buffer_handle;
        glGenBuffers(1, &buffer_handle);
        glBindBuffer(GL_ARRAY_BUFFER, buffer_handle);
        glBufferData(GL_ARRAY_BUFFER, this->stride * this->num_rows,
                     &this->raw_data[0], GL_STATIC_DRAW);

        size_t offset = 0;
        for (size_t i = 0; i < attribs.size(); ++i)
                attribs[i].setup(&offset, this->stride);

        /* Leave buffer bound for later draw calls */

        return this->num_rows;
}


/**
 * Set up a vertex buffer object for the program prog based on the
 * data encoded in text_start.  text_end indicates the end of the text
 * string; if it is NULL, the string is assumed to be null-terminated.
 *
 * Return value is the number of rows of vertex data found.
 *
 * For details about the format of the text string, see the comment at
 * the top of this file.
 */
size_t
setup_vbo_from_text(GLuint prog, const char *text_start, const char *text_end)
{
        if (text_end == NULL)
                text_end = text_start + strlen(text_start);
        std::string text(text_start, text_end);
        return vbo_data(text, prog).setup();
}