【发布时间】：2015-02-25 14:20:23
【问题描述】：
我刚开始学习 OpenGL，这是我第一个绘制立方体的程序。我在这里很迷茫，因为我能够通过在 2d 中指定矩形的坐标来绘制一个矩形，但是我不能通过以 (x, y, z) 格式指定坐标来绘制立方体。我在这里错过了什么？
代码如下：
#include <GL/glew.h>
#include <GL/gl.h>
#include <math.h>
#include <GLFW/glfw3.h>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
// Open an OpenGL window
GLFWwindow* window;
/****Step 1: define vertices in (x, y, z) form****/
// Coordinates to draw a cube
const GLdouble coordinates[8][3] = {
{-0.5, -0.5, -0.5},
{0.5, -0.5, -0.5},
{0.5, -0.5, 0.5},
{-0.5, -0.5, 0.5},
{-0.5, 0.5, 0.5},
{-0.5, 0.5, -0.5},
{0.5, 0.5, -0.5},
{0.5, 0.5, 0.5}
};
/************************/
int main( void ) {
if (!glfwInit()){
fprintf(stderr, "Failed to initialize GLFW.\n");
return -1;
}
// Create a windowed mode window and its OpenGL context
window = glfwCreateWindow(700, 500, "Hello World", NULL, NULL);
if (window == NULL) {
fprintf(stderr, "glfw failed to create window.\n");
//glfwTerminate();
return -1;
}
// Make the window's context current
glfwMakeContextCurrent(window);
glewInit();
if (glewInit() != GLEW_OK){
fprintf(stderr, "Failed to initialize GLEW: %s.\n", glewGetErrorString(glewInit()));
return -1;
}
// 4x anti aliasing
glfwWindowHint(GLFW_SAMPLES, 4);
int cube_size = sizeof(coordinates)/sizeof(coordinates[0]);
/**Step 2: send this cube vertices to OpenGL through a buffer**/
GLuint vertexBuffer; // Declare vertex buffer
glGenBuffers(1, &vertexBuffer); // generating 1 buffer, put resulting identifier in this buffer
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, cube_size*12, coordinates, GL_STATIC_DRAW);
/************************/
std::cout << sizeof(coordinates)/sizeof(coordinates[0]);
/**Step 3: Main loop for OpenGL draw the shape**
/* Main loop */
do{
glClearColor(1.0, 0.1, 0.1, .0);
glClear(GL_COLOR_BUFFER_BIT);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glDrawArrays(GL_LINE_LOOP, 0, cube_size);
glDisableVertexAttribArray(0);
// Swap front and back rendering buffers
glfwSwapBuffers(window);
//Poll for and process events
glfwPollEvents();
} // check if the ESC key was pressed or the window was closed
while(glfwGetKey(window, GLFW_KEY_ESCAPE) != GLFW_PRESS && glfwWindowShouldClose(window) == 0);
/***********************************************/
// Close window and terminate GLFW
glfwDestroyWindow(window);
glfwTerminate();
// Exit program
exit( EXIT_SUCCESS );
}
【问题讨论】：
-
问题出在哪里？哪一行？
-
请注意，调用 glfwWindowHint() 不会影响打开的窗口，它们只会影响随后调用 glfwCreateWindow() 的窗口。见：glfw.org/docs/latest/…
-
实际渲染的是什么？在什么操作系统上使用什么 gfx 硬件？您是否尝试过将透明颜色从黑色更改为其他颜色？ （如果启用了没有纹理绑定的纹理，结果颜色通常为黑色）您是否将对象和相机移动到 Z 轴的两侧？ （透视矩阵通常在负 Z 轴上查看）