Question

I m trying to figure out how to work with VBOs, using an OpenGL 2.0 rendering context. I ve got a 2D (ortho) rendering context set up, and I can draw a simple rectangle like this:

glBegin(GL_QUADS);
   glColor4f(1, 1, 1, 1);
   glVertex2f(0, 0);
   glVertex2f(0, 10);
   glVertex2f(100, 10);
   glVertex2f(100, 0);
glEnd;

但是,当我试图与一个VBO打交道时,它就失败了。我设立了《维也纳行动计划》,其数据与以前相同:

procedure initialize;
const
   VERTICES: array[1..8] of single =
   (
   0, 0,
   0, 10,
   100, 10,
   100, 0
   );
begin
   glEnable(GL_VERTEX_ARRAY);
   glGenBuffers(1, @VBO);
   glBindBuffer(GL_ARRAY_BUFFER, VBO);
   glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), @VERTICES[1], GL_DYNAMIC_DRAW);
   glBindBuffer(GL_ARRAY_BUFFER, 0);
end;

我试图这样做:

begin
   glColor4f(1, 1, 1, 1);
   glEnableClientState(GL_VERTEX_ARRAY);
   glBindBuffer(GL_ARRAY_BUFFER, VBO);
   glVertexPointer(2, GL_FLOAT, 0, 0);
   glDrawArrays(GL_QUADS, 0, 1);
   glBindBuffer(GL_ARRAY_BUFFER, 0);
end;

从我看,这应该奏效。我通过gDEBugger管理,没有GL错误,VBO的数据被正确地装上,但在我冲动缓冲器时,没有实际出现。改变垂直阵列中的数据,以使用正常坐标(0.1.0)也无所作为。任何想法,我会错做什么? (假设情况本身是正确的,GL的功能点全都是正确的。)

Answer 1

glDrawArrays(GL_QUADS, 0, 1);

看一看你试图用一个独一无二的顶点。你们还需要三个方面:

glDrawArrays(GL_QUADS, 0, 4);

或转向点数:

glDrawArrays(GL_POINTS, 0, 1);

友情链接