Путаница в буфере вершин / индексов с OpenGL 3.3

Я пытаюсь получить 3D-куб, отрисованный с использованием OpenGL 3.3. Я основываю свой код примерно на код от Глава 4 книги OpenGL

Вот мой код:

// Attempt to make a cube in OpenGL 3.3, using GLEW and GLFW
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <cmath>
// Include GLEW (openGL Extension Wrangler)
#define GLEW_STATIC
#include <GL/glew.h>
// Include GLFW (openGL FrameWork)
#include <GL/glfw.h>
// Define this helper macro to get an array position
#define BUFFER_OFFSET(i) ((char *)NULL + (i))

static const double PI = 3.14159265358979323846;

float radians(float inDeg)
{
return inDeg * PI/180.0 ;
}

struct Vertex
{ // 64 bytes = 16 x 4 bytes per float
GLfloat x, y, z ;         // position coordinates
GLfloat nx, ny, nz ;      // normal coordinates
GLfloat r, g, b, a ;      // color coordinates for vertex shading
GLfloat s0, t0 ;          // s and t are the standard texture coordinates
GLfloat s1, t1 ;          // (just used as padding)
GLfloat s2, t2 ;          // (just used as padding)
} ;
// Vertex Attributes
GLuint      vertexSize       = sizeof( Vertex ) ;
GLuint      positionOffset   = 0 ;
GLuint      colorOffset      = 24 ;
// Vertex Data - stored dynamically, see BuildCube()
Vertex     *vertexData ;
GLuint     *indexData  ;
GLuint      vertexDataLength = 8  ;
GLuint      indexDataLength  = 36 ;

struct Matrix
{ // 64 bytes = 16 x 4 bytes per float
GLfloat m[16] ;
} ;
// Matrix Data
Matrix      ModelMatrix ;
Matrix      ViewMatrix  ;
Matrix      ProjMatrix  ;

Matrix IdentityMatrix(void)
{   // set the diagonal values to one
Matrix out ;
out.m[0]  =  1.0 ; out.m[1]  =  0.0 ; out.m[2]  =  0.0 ; out.m[3]  =  0.0 ;
out.m[4]  =  0.0 ; out.m[5]  =  1.0 ; out.m[6]  =  0.0 ; out.m[7]  =  0.0 ;
out.m[8]  =  0.0 ; out.m[9]  =  0.0 ; out.m[10] =  1.0 ; out.m[11] =  0.0 ;
out.m[12] =  0.0 ; out.m[13] =  0.0 ; out.m[14] =  0.0 ; out.m[15] =  1.0 ;
return out ;
}

Matrix ZeroMatrix(void)
{   // set all values to zero
Matrix out ;
out.m[0]  =  0.0 ; out.m[1]  =  0.0 ; out.m[2]  =  0.0 ; out.m[3]  =  0.0 ;
out.m[4]  =  0.0 ; out.m[5]  =  0.0 ; out.m[6]  =  0.0 ; out.m[7]  =  0.0 ;
out.m[8]  =  0.0 ; out.m[9]  =  0.0 ; out.m[10] =  0.0 ; out.m[11] =  0.0 ;
out.m[12] =  0.0 ; out.m[13] =  0.0 ; out.m[14] =  0.0 ; out.m[15] =  0.0 ;
return out ;
}

Matrix Multiply(const Matrix *m1, const Matrix *m2)
{
// Since these are note REALLY matrixes, we can get away with a shortcut
Matrix out = IdentityMatrix() ;
GLuint row, column, row_offset ;
for (row = 0; row < 4; row++)
{
row_offset = row * 4 ;
for (column = 0; column < 4; column++)
{
out.m[row_offset + column] =
(m1->m[row_offset + 0] * m2->m[column + 0]) +
(m1->m[row_offset + 1] * m2->m[column + 4]) +
(m1->m[row_offset + 2] * m2->m[column + 8]) +
(m1->m[row_offset + 3] * m2->m[column + 12]) ;
}
}
return out ;
}

void Translate(Matrix &inMat, GLfloat dx, GLfloat dy, GLfloat dz)
{
Matrix TM = IdentityMatrix() ;
TM.m[3]  =  dx ;
TM.m[7]  =  dy ;
TM.m[11] =  dz ;
inMat = Multiply(&inMat, &TM) ;
}

void Rotate(Matrix &inMat, GLfloat xAng, GLfloat yAng, GLfloat zAng)
{   // rotates a vector or point around the origin at the specified angles
// create the half-angle values in radians
GLfloat rad_x_ang = radians(xAng)/2.0 * -1.0 ;      // multiply by -1 to make the rotation right-handed
GLfloat rad_y_ang = radians(yAng)/2.0        ;
GLfloat rad_z_ang = radians(zAng)/2.0 ;      // multiply by -1 to make the rotation right-handed
// compute sin and cos values, so they're not repeated a LOT
GLfloat cosX = cos(rad_x_ang) ;
GLfloat sinX = sin(rad_x_ang) ;
GLfloat cosY = cos(rad_y_ang) ;
GLfloat sinY = sin(rad_y_ang) ;
GLfloat cosZ = cos(rad_z_ang) ;
GLfloat sinZ = sin(rad_z_ang) ;
// create quaternion vector: Q
GLfloat q0 = cosZ * cosY * cosX + sinZ * sinY * sinX ;
GLfloat q1 = sinZ * cosY * cosX - cosZ * sinY * sinX ;
GLfloat q2 = cosZ * sinY * cosX + sinZ * cosY * sinX ;
GLfloat q3 = cosZ * cosY * sinX - sinZ * sinY * cosX ;
// create rotation matrix
Matrix RM ;
RM.m[0]  = q0*q0+q1*q1+q2*q2+q3*q3 ; RM.m[1]  = 0.0                     ; RM.m[2]  = 0.0                     ; RM.m[3]  = 0.0                     ;
RM.m[4]  = 0.0                     ; RM.m[5]  = q0*q0-q1*q1-q2*q2+q3*q3 ; RM.m[6]  = 2*q2*q3 - 2*q0*q1       ; RM.m[7]  = 2*q1*q3 + 2*q0*q2       ;
RM.m[8]  = 0.0                     ; RM.m[9]  = 2*q2*q3 + 2*q0*q1       ; RM.m[10] = q0*q0-q1*q1+q2*q2-q3*q3 ; RM.m[11] = 2*q1*q2 - 2*q0*q3       ;
RM.m[12] = 0.0                     ; RM.m[13] = 2*q1*q3 - 2*q0*q2       ; RM.m[14] = 2*q1*q2 + 2*q0*q3       ; RM.m[15] = q0*q0+q1*q1-q2*q2-q3*q3 ;
// multiply the new rotational matrix with the current incoming matrix
inMat = Multiply(&inMat, &RM) ;
}

const GLchar* VertexShader =
{
"#version 330\n"\
"attribute vec3 in_Position;\n"\
"attribute vec4 in_Color;\n"\
"uniform   mat4 ModelMatrix;\n"\
"uniform   mat4 ViewMatrix;\n"\
"uniform   mat4 ProjMatrix ;\n"\
"out       vec4 ex_Color;\n"\
"void main(void)\n"\
"{\n"\
"   gl_Position = (ProjMatrix * ViewMatrix * ModelMatrix) * vec4(in_Position, 1.0);\n"\
"   ex_Color    = in_Color;\n"\
"}\n"};

const GLchar* FragmentShader =
{
"#version 330\n"\
"in  vec4 ex_Color ;\n"\
"out vec4 out_Color ;\n"\
"void main(void)\n"\
"{\n"\
"   out_Color = ex_Color ;\n"\
"}\n"};

// Shader Attribute IDs
GLuint      attribute_in_Position ;
GLuint      attribute_in_Color ;
GLuint      uniform_ModelMatrix ;
GLuint      uniform_ViewMatrix ;
GLuint      uniform_ProjMatrix ;
// OpenGL Object IDs
GLuint      VertShaderID ;
GLuint      FragShaderID ;
GLuint      GLSLProgID ;
GLuint      vaoID ;
GLuint      vboID ;
GLuint      iboID ;

// Forward declare functions
void        BuildCube(void) ;
void        CreateShaders(void) ;
void        DestroyShaders(void) ;
void        InitStuff(void) ;
bool        DrawStuff(int) ;
void        KillStuff(void) ;

void BuildCube(void)
{
vertexData = new Vertex[8] ;   // create a dynamic memory array of 8 vertices
indexData  = new GLuint[36] ;
// specify only 8 vertices (ignore texture and normals for now)
vertexData[0].x  =  0.5 ; vertexData[0].y  =  0.5 ; vertexData[0].z  =  0.5 ;
vertexData[1].x  = -0.5 ; vertexData[1].y  =  0.5 ; vertexData[1].z  =  0.5 ;
vertexData[2].x  = -0.5 ; vertexData[2].y  = -0.5 ; vertexData[2].z  =  0.5 ;
vertexData[3].x  =  0.5 ; vertexData[3].y  = -0.5 ; vertexData[3].z  =  0.5 ;
vertexData[4].x  =  0.5 ; vertexData[4].y  =  0.5 ; vertexData[4].z  = -0.5 ;
vertexData[5].x  = -0.5 ; vertexData[5].y  =  0.5 ; vertexData[5].z  = -0.5 ;
vertexData[6].x  = -0.5 ; vertexData[6].y  = -0.5 ; vertexData[6].z  = -0.5 ;
vertexData[7].x  =  0.5 ; vertexData[7].y  = -0.5 ; vertexData[7].z  = -0.5 ;
// specify all triangles
indexData[0]  = 0 ; indexData[1]  = 1 ; indexData[2]  = 2 ;  // top
indexData[3]  = 2 ; indexData[4]  = 3 ; indexData[5]  = 0 ;
indexData[6]  = 4 ; indexData[7]  = 6 ; indexData[8]  = 5 ;  // bottom
indexData[9]  = 6 ; indexData[10] = 4 ; indexData[11] = 7 ;
indexData[12] = 2 ; indexData[13] = 1 ; indexData[14] = 5 ;  // left
indexData[15] = 5 ; indexData[16] = 6 ; indexData[17] = 2 ;
indexData[18] = 0 ; indexData[19] = 3 ; indexData[20] = 4 ;  // right
indexData[21] = 3 ; indexData[22] = 7 ; indexData[23] = 4 ;
indexData[24] = 1 ; indexData[25] = 0 ; indexData[26] = 5 ;  // front
indexData[27] = 0 ; indexData[28] = 4 ; indexData[29] = 5 ;
indexData[30] = 3 ; indexData[31] = 2 ; indexData[32] = 6 ;  // back
indexData[33] = 6 ; indexData[34] = 7 ; indexData[35] = 3 ;
// specify the colors
for (unsigned int ii = 0; ii < 8; ii++)
{   //
vertexData[ii].r =  vertexData[ii].x + 0.5 ;
vertexData[ii].g =  vertexData[ii].y + 0.5 ;
vertexData[ii].b =  vertexData[ii].z + 0.5 ;
vertexData[ii].a =  1.0 ;
}
// end BuildCube()
}

void CreateShaders(void)
{
GLenum ErrorCheckValue = glGetError();
// establish vertex shader
VertShaderID = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(VertShaderID, 1, &VertexShader, NULL);
glCompileShader(VertShaderID);
// establish fragment shader
FragShaderID = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(FragShaderID, 1, &FragmentShader, NULL);
glCompileShader(FragShaderID);
// set the GLSL program ID
GLSLProgID = glCreateProgram();
// link the vertex and fragment shaders
glAttachShader(GLSLProgID, VertShaderID);
glAttachShader(GLSLProgID, FragShaderID);
glLinkProgram(GLSLProgID);
glUseProgram(GLSLProgID);
// check for errors before continuing
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not create the shaders: %s \n",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}

void DestroyShaders(void)
{
if (!glfwGetWindowParam(GLFW_OPENED)) { return ; }
GLenum ErrorCheckValue = glGetError();
glUseProgram(0);
glDetachShader(GLSLProgID, VertShaderID);
glDetachShader(GLSLProgID, FragShaderID);
glDeleteShader(FragShaderID);
glDeleteShader(VertShaderID);
glDeleteProgram(GLSLProgID);
// check for errors last
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not destroy the shaders: %s \n",
gluErrorString(ErrorCheckValue)
) ;
exit(-1) ;
}
}

void InitStuff(void)
{
// Initialise GLFW extension
if( !glfwInit() )
{   // If the extension failed to initialize, then error out and leave.
fprintf( stderr, "Failed to initialize GLFW\n" ) ;
return ;
}
// Establish OpenGL version 3.3
glfwOpenWindowHint(GLFW_FSAA_SAMPLES, 4);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);    // This compensates for the bug in GLEW
// Open a window and create its OpenGL context
if( !glfwOpenWindow( 512, 512, 0,0,0,0, 0,0, GLFW_WINDOW ) )
{
fprintf( stderr, "Failed to open GLFW window.\n" ) ;
glfwTerminate() ;
exit(-1) ;
}
// Initialize GLEW extension
if (glewInit() != GLEW_OK)
{
fprintf(stderr, "Failed to initialize GLEW\n") ;
exit(-1) ;
}
// Set the title on the upper left of the window
glfwSetWindowTitle("Test Window") ;
// Ensure we can capture the escape key being pressed below
glfwEnable( GLFW_STICKY_KEYS ) ;
// Clear Screen And Depth Buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) ;

// Establish the matrixes
int width, height ;
glfwGetWindowSize( &width, &height );       // assess window size
height = height > 0 ? height : 1;           // avoid div/0 error
// calculate the projection matrix values
GLfloat     fov_y          = 45.0 ;
GLfloat     aspect_ratio   = (GLfloat) width / (GLfloat) height ;
GLfloat     near_plane     = 1.0 ;
GLfloat     far_plane      = 100.0 ;
GLfloat     y_scale        = 1.0 / tan( radians(fov_y / 2.0) ) ;
GLfloat     x_scale        = y_scale / aspect_ratio ;
GLfloat     frustum_length = far_plane - near_plane ;
ProjMatrix = ZeroMatrix() ;
ProjMatrix.m[0]  =   x_scale ;
ProjMatrix.m[5]  =   y_scale ;
ProjMatrix.m[10] =  -((far_plane + near_plane) / frustum_length) ;
ProjMatrix.m[11] =  -1.0 ;
ProjMatrix.m[14] =  -((2.0 * near_plane * far_plane) / frustum_length) ;

// Establish the model and view matrixes as identity matrixes
ModelMatrix = IdentityMatrix() ;
ViewMatrix = IdentityMatrix() ;

Translate(ViewMatrix, 0.0, 0.0, -2.0) ;
// Creat the error enumeration
GLenum ErrorCheckValue = glGetError();

// Create the vertex and fragment shaders
CreateShaders() ;
// Bind the vertex shader attributes to their IDs
attribute_in_Position =  glGetAttribLocation(GLSLProgID, "in_Position") ;
attribute_in_Color    =  glGetAttribLocation(GLSLProgID, "in_Color"   ) ;
uniform_ModelMatrix   = glGetUniformLocation(GLSLProgID, "ModelMatrix") ;
uniform_ViewMatrix    = glGetUniformLocation(GLSLProgID, "ViewMatrix" ) ;
uniform_ProjMatrix    = glGetUniformLocation(GLSLProgID, "ProjMatrix" ) ;

// upload the projection matrix data to the GPU
glUniformMatrix4fv(uniform_ModelMatrix, 1, GL_TRUE, ModelMatrix.m);
glUniformMatrix4fv(uniform_ViewMatrix , 1, GL_TRUE, ViewMatrix.m );
glUniformMatrix4fv(uniform_ProjMatrix , 1, GL_TRUE, ProjMatrix.m );

// Build the Cube Geometry
BuildCube() ;

// Initialize the Vertex Buffer Object in OpenGL
glGenBuffers(1, &vboID);
glBindBuffer(GL_ARRAY_BUFFER, vboID);
glBufferData(GL_ARRAY_BUFFER, vertexSize * vertexDataLength, NULL, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, vertexSize * vertexDataLength, vertexData);
glBindBuffer(GL_ARRAY_BUFFER, 0);
// Initialize the Index Buffer Object in OpenGL
glGenBuffers(1, &iboID);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, iboID);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint) * indexDataLength, NULL, GL_STATIC_DRAW);
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, sizeof(GLuint) * indexDataLength, indexData);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);// Check for errors, then done
ErrorCheckValue = glGetError() ;
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not complete initialization: %s \n",
gluErrorString(ErrorCheckValue)
) ;
exit(-1) ;
}
// end InitStuff()
}

bool DrawStuff(int frame)
{
int width, height ;
glfwGetWindowSize( &width, &height ) ;   // First, re-assess the window size
height = height > 0 ? height : 1 ;       // avoid div/0 error
// for now, vary the background color so we know it's updating
GLfloat phase_offset = 125.0f ;
GLfloat speed_mult   = 0.01f ;
GLfloat bgColorR = 0.5f * ( sin( (frame-0)*speed_mult ) + 1.0f );
GLfloat bgColorG = 0.5f * ( sin( (frame-phase_offset)*speed_mult ) + 1.0f );
GLfloat bgColorB = 0.5f * ( sin( (frame-2*phase_offset)*speed_mult ) + 1.0f );
glClearColor( bgColorR, bgColorG, bgColorB, 0.0f );
// Handle projection stuff
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
glViewport( 0, 0, width, height );
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//
GLenum ErrorCheckValue = glGetError();

glEnable(GL_DEPTH_TEST) ;
glDepthFunc(GL_LESS) ;
glEnable(GL_CULL_FACE) ;
glCullFace(GL_BACK) ;
glFrontFace(GL_CCW) ;

ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not set OpenGL culling options: %s \n",
gluErrorString(ErrorCheckValue)
) ;
exit(-1) ;
}// switch to model view mode
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();

// Assume I have multiple VBOs, but streamline for only one for now
glPushMatrix() ;

// re-bind the VBO data into the buffer
glBindBuffer(GL_ARRAY_BUFFER, vboID) ;
glVertexAttribPointer(attribute_in_Color, 4, GL_FLOAT, GL_FALSE, vertexSize, BUFFER_OFFSET(colorOffset)) ;
glEnableVertexAttribArray(attribute_in_Color) ;

glBindBuffer(GL_ARRAY_BUFFER, vboID) ;
glVertexAttribPointer(attribute_in_Position, 3, GL_FLOAT, GL_FALSE, vertexSize, BUFFER_OFFSET(positionOffset)) ;
glEnableVertexAttribArray(attribute_in_Position) ;

// bind the indexes of the vertices to the buffer
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, iboID) ;

Rotate(ModelMatrix, 0.0, 0.0, 0.5) ;
glUniformMatrix4fv(uniform_ModelMatrix, 1, GL_TRUE, ModelMatrix.m);

ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not prep for draw: %s \n",
gluErrorString(ErrorCheckValue)
) ;
exit(-1) ;
}

glDrawArrays(GL_TRIANGLES, 0, indexDataLength);

glDisableVertexAttribArray(attribute_in_Color) ;
glDisableVertexAttribArray(attribute_in_Position) ;
glBindBuffer(GL_ARRAY_BUFFER, 0) ;
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0) ;

glPopMatrix();
// lastly, swap buffers, then return the status
glfwSwapBuffers();
return !glfwGetKey(GLFW_KEY_ESC) && glfwGetWindowParam(GLFW_OPENED);
}

void KillStuff(void)
{
DestroyShaders();
glfwTerminate();
}

int main()
{
int     frame = 0 ;
bool    running = true;
InitStuff() ;
while(running)
{
frame++;
running = DrawStuff(frame) ;
}
KillStuff() ;
return 0;
}

В результате получается около 3 частично сформированных треугольников, которые не следуют правильной индексации. Я думаю, что проблема в индексном буфере, но я мог бы действительно помочь понять, правильно ли я использую индексный и вершинный буферы или нет. Я довольно смущен тем, что я делаю неправильно.