If you have a VBO bound then the pointer
argument to the gl*Pointer()
calls is interpreted as a byte offset from the beginning of the VBO, not an actual pointer. Your usage is consistent with vertex array usage though.
So for your vertex
struct x
starts at byte zero and r
starts at byte sizeof(float) * 4
.
Also, your mouse callback reset your vertex vector on every call so you would never be able have more than one vertex in it at any given time. It also leaked VBO names via the glGenBuffers()
in initVertexBuffer()
.
Give this a shot:
#include <GL/glew.h>
#include <GL/glut.h>
#include <iostream>
#include <vector>
struct vertex
{
float x, y;
float u, v;
float r, g, b;
};
GLuint vboId;
std::vector<vertex> vertices;
void mouseCB(int button, int state, int x, int y)
{
y = glutGet( GLUT_WINDOW_HEIGHT ) - y;
if (state == GLUT_DOWN)
{
vertex temp = {x, y, 1, 0, 1, 0, 0}; // default red color
vertices.push_back(temp);
glBindBuffer(GL_ARRAY_BUFFER, vboId);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertex) * vertices.size(), &vertices[0], GL_STATIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
glutPostRedisplay();
}
void displayCB()
{
glClearColor(1, 1, 1, 0);
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
double w = glutGet( GLUT_WINDOW_WIDTH );
double h = glutGet( GLUT_WINDOW_HEIGHT );
glOrtho( 0, w, 0, h, -1, 1 );
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
if ( vertices.size() > 1 )
{
glBindBuffer(GL_ARRAY_BUFFER, vboId);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glVertexPointer(2, GL_FLOAT, sizeof(vertex), (void*)(sizeof( float ) * 0));
glColorPointer(3, GL_FLOAT, sizeof(vertex), (void*)(sizeof( float ) * 4));
glDrawArrays(GL_LINE_STRIP, 0, vertices.size());
glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_COLOR_ARRAY);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
glutSwapBuffers();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB|GLUT_DOUBLE|GLUT_DEPTH);
glutInitWindowSize(500, 500);
glutInitWindowPosition(100, 100);
glutCreateWindow("Test");
// initialize glew
glewExperimental = GL_TRUE;
GLenum glewInitResult = glewInit();
if (GLEW_OK != glewInitResult) {
std::cerr << "Error initializing glew." << std::endl;
return 1;
}
glGenBuffers(1, &vboId);
glutDisplayFunc(displayCB);
glutMouseFunc(mouseCB);
glutMainLoop();
return 0;
}