Opengl简单四元渲染

Question

你知道为什么这不起作用吗？

旧的立即模式可以工作，但我想使用VAO和VBO。

(附言：我知道VOA创建应该只创建一次，但我用这种方法来构建它以进行测试。测试后我会移动这些行(

private void allocateIndexBuffer(GL2 graphics, int[] indices) {
int[] id = new int[1];
graphics.glGenBuffers(1, id, 0);
int vboId = id[0];
graphics.glBindBuffer(GL2.GL_ELEMENT_ARRAY_BUFFER, vboId);

IntBuffer buffer = IntBuffer.allocate(indices.length);
buffer.put(0, indices);
buffer.flip();
graphics.glBufferData(GL2.GL_ELEMENT_ARRAY_BUFFER, indices.length, buffer, GL2.GL_DYNAMIC_DRAW);

//graphics.glDeleteBuffers(vboId, buffer); TODO: clean up when on closing
}
private void allocateAttributeBuffer(GL2 graphics, int attribute, float[] data) {
int[] id = new int[1];
graphics.glGenBuffers(1, id, 0);
int vboId = id[0];
graphics.glBindBuffer(GL2.GL_ARRAY_BUFFER, vboId); //juste remplir vboId ou le remplacer à chaque fois ?
FloatBuffer buffer = FloatBuffer.allocate(data.length);
buffer.put(0, data);
buffer.flip();

graphics.glBufferData(GL2.GL_ARRAY_BUFFER, data.length, buffer, GL2.GL_DYNAMIC_DRAW);
graphics.glVertexAttribPointer(0, 2, GL2.GL_FLOAT, false, 0, 0); //once the buffer is bound
graphics.glEnableVertexAttribArray(0);
graphics.glBindBuffer(GL2.GL_ARRAY_BUFFER, 0);

//graphics.glDeleteBuffers(vboId, buffer); TODO: clean up when on closing
//graphics.glDeleteVertexArrays(vboId, null); TODO: clean up vaos
}
@Override
protected void draw(GL2 graphics) {
String mode = "new";
if (mode.equals("new")) {
float[] vertices = {
bounds.getX(), bounds.getY(),
bounds.getX(), bounds.getY() + bounds.getHeight(),
bounds.getX() + bounds.getWidth(), bounds.getY() + bounds.getHeight(),
bounds.getX() + bounds.getWidth(), bounds.getY(),
};
int[] indices = { 0, 1, 2, 2, 1, 3 };
//creation vao
int[] id = new int[1];
graphics.glGenVertexArrays(1, id, 0);
int vaoId = id[0];
graphics.glBindVertexArray(vaoId);
allocateIndexBuffer(graphics, indices);
allocateAttributeBuffer(graphics, 0, vertices);
graphics.glBindVertexArray(0);
//render
graphics.glBindVertexArray(vaoId);
graphics.glEnableVertexAttribArray(0);
graphics.glDrawElements(GL2.GL_TRIANGLES, indices.length, GL2.GL_UNSIGNED_INT, 0);
graphics.glDisableVertexAttribArray(0);
graphics.glBindVertexArray(0);
graphics.glFlush();
} else if (mode.equals("old")) {
graphics.glColor3f(255, 0, 0);
graphics.glBegin(GL2.GL_QUADS);
graphics.glVertex2f(bounds.getX(), bounds.getY());
graphics.glVertex2f(bounds.getX() + bounds.getWidth(), bounds.getY());
graphics.glVertex2f(bounds.getX() + bounds.getWidth(), bounds.getY() + bounds.getHeight());
graphics.glVertex2f(bounds.getX(), bounds.getY() + bounds.getHeight());
graphics.glEnd();
}
}

Answer 1

缓冲区的大小必须以字节为单位指定(请参阅glBufferData(；

graphics.glBufferData(GL2.GL_ELEMENT_ARRAY_BUFFER, indices.length, buffer, GL2.GL_DYNAMIC_DRAW);

graphics.glBufferData(GL2.GL_ELEMENT_ARRAY_BUFFER, indices.capacity() * 4,
buffer, GL2.GL_DYNAMIC_DRAW);

graphics.glBufferData(GL2.GL_ARRAY_BUFFER, data.length, buffer, GL2.GL_DYNAMIC_DRAW);

graphics.glBufferData(GL2.GL_ARRAY_BUFFER, data.capacity() * 4,
buffer, GL2.GL_DYNAMIC_DRAW);