I have trouble rendering some geometry by using a vertex buffer object. I intend to draw a plane of points, so basically one vertex at every discrete position in my space. However, I cannot render that plane, as every time I call glDrawElements(...), application crashes returning an access violation exception. There must be some mistake while initialization, I guess.
This is what I have so far:
#define SPACE_X 512
#define SPACE_Z 512
typedef struct{
GLfloat x, y, z; // position
GLfloat nx, ny, nz; // normals
GLfloat r, g, b, a; // colors
} Vertex;
typedef struct{
GLuint i; // index
} Index;
// create vertex buffer
GLuint vertexBufferObject;
glGenBuffers(1, &vertexBufferObject);
// create index buffer
GLuint indexBufferObject;
glGenBuffers(1, &indexBufferObject);
// determine number of vertices / primitives
const int numberOfVertices = SPACE_X * SPACE_Z;
const int numberOfPrimitives = numberOfVertices; // As I'm going to render GL_POINTS, number of primitives is the same as number of vertices
// create vertex array
Vertex* vertexArray = new Vertex[numberOfVertices];
// create index array
Index* indexArray = new Index[numberOfPrimitives];
// create planes (vertex array)
// color of the vertices is red for now
int index = -1;
for(GLfloat x = -SPACE_X / 2; x < SPACE_X / 2; x++) {
for(GLfloat z = -SPACE_Z / 2; z < SPACE_Z / 2; z++) {
index++;
vertexArray[index].x = x;
vertexArray[index].y = 0.0f;
vertexArray[index].z = z;
vertexArray[index].nx = 0.0f;
vertexArray[index].ny = 0.0f;
vertexArray[index].nz = 1.0f;
vertexArray[index].r = 1.0;
vertexArray[index].g = 0.0;
vertexArray[index].b = 0.0;
vertexArray[index].a = 1.0;
}
}
// bind vertex buffer
glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject);
// buffer vertex array
glBufferData(GL_ARRAY_BUFFER, numberOfVertices * sizeof(Vertex), vertexArray, GL_DTREAM_DRAW);
// bind vertex buffer again
glBindBuffer(GL_ARRAY_BUFFER, vertexBufferObject);
// enable attrib index 0 (positions)
glEnableVertexAttribArray(0);
// pass positions in
glVertexAttribPointer((GLuint)0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), vertexArray);
// enable attribute index 1 (normals)
glEnableVertexAttribArray(1);
// pass normals in
glVertexAttribPointer((GLuint)1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), &vertexArray[0].nx);
// enable attribute index 2 (colors)
glEnableVertexAttribArray(2);
// pass colors in
glVertexAttribPointer((GLuint)2, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), &vertexArray[0].r);
// create index array
for(GLunit i = 0; i < numberOfPrimitives; i++) {
indexArray[i].i = i;
}
// bind buffer
glBindBuffer(GL_ELEMENET_ARRAY_BUFFER, indexBufferObject);
// buffer indices
glBufferData(GL_ELEMENET_ARRAY_BUFFER, numberOfPrimitives * sizeof(Index), indexArray, GL_STREAM_DRAW);
// bind buffer again
glBindBuffer(GL_ELEMENET_ARRAY_BUFFER, indexBufferObject);
// AND HERE IT CRASHES!
// draw plane of GL_POINTS
glDrawElements(GL_POINTS, numberOfPrimitives, GL_UNSIGNED_INT, indexArray);
// bind default buffers
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
// delete vertex / index buffers
glDeleteBuffers(1, &vertexBufferObject);
glDeleteBuffers(1, &indexBufferObject);
delete[] vertexArray;
vertexArray = NULL;
delete[] indexArray;
indexArray = NULL;
