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OpenGL 3.3을 사용하여 렌더링 된 3D 큐브를 얻으려고합니다.OpenGL 3.3과의 정점/인덱스 버퍼 혼동
// 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;
}
결과는 정말 적절한 색인을 따르지 않는 약 3 부분적으로 형성된 삼각형이다 : 나는 여기 Chapter 4 of the OpenGL book
에서 코드 떨어져 거의 내 코드를 기반으로 작성하는 것은 내 코드입니다. 나는 문제가 인덱스 버퍼에 있다고 생각하지만 실제로 인덱스와 버텍스 버퍼를 잘못 사용하고 있는지 이해하는 데 도움이 될 수 있습니다. 나는 내가 뭘 잘못하고 있는지 오히려 혼란 스럽다.
제 사과, 나는 "compileable"코드를 게시하려고했습니다. 나는 아직도 간결한 OpenGL 응용 프로그램을 만드는 방법을 배우고있다. – user1731740
오 오케이, 그건 고귀한 노력이라고 생각합니다. 불행하게도 실제로는 현대식 OpenGL 응용 프로그램을 작성하는 간결한 방법이 없습니다. 많은 프레임 워크가 필요합니다. 가독성과 컴파일 가능성의 절충안이라고 생각합니다. 문제에 가장 적합한 것으로 생각하는 것을 선택할 수 있지만, 제 의견은 작은 코드 덩어리가 더 쉽고 대답하기 쉽다는 것입니다. – Tim
거룩한 와우! 나는 당신이 말했듯이 glDrawElements로 바꾸었고 지금은 큐브입니다. 고맙습니다! – user1731740