我是OpenGL的初学者，只是想学习（暂时从freeglut开始）。到目前为止，我有以下代码，应该绘制一些基本的3D对象。问题在于，无论我放入渲染函数（尽管它确实执行），它只显示一个空白窗口。
#include "stdafx.h"
#include <iostream>
#include "dependente\glew\glew.h"
#include "dependente\freeglut\glut.h"
void render()
{
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glEnable(GL_DEPTH_TEST);
glTranslatef(-1.5f, 1.0f, -6.0f); // Translate back and to the left
glPushMatrix(); // Push the current modelview matrix on the matrix // Rotate on all 3 axis
glBegin(GL_TRIANGLES); // Draw a pyramid
glColor3f(1.0f, 0.0f, 0.0f); // Red
glVertex3f(0.0f, 1.0f, 0.0f); // Top of front face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(-1.0f, -1.0f, 1.0f); // Left of front face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(1.0f, -1.0f, 1.0f); // Right of front face
glColor3f(1.0f, 0.0f, 0.0f); // Red
glVertex3f(0.0f, 1.0f, 0.0f); // Top of right face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(1.0f, -1.0f, 1.0f); // Left of right face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(1.0f, -1.0f, -1.0f); // Right of right face
glColor3f(1.0f, 0.0f, 0.0f); // Red
glVertex3f(0.0f, 1.0f, 0.0f); // Top of back face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(1.0f, -1.0f, -1.0f); // Left of back face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(-1.0f, -1.0f, -1.0f); // Right of back face
glColor3f(1.0f, 0.0f, 0.0f); // Red
glVertex3f(0.0f, 1.0f, 0.0f); // Top of left face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(-1.0f, -1.0f, -1.0f); // Left of left face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(-1.0f, -1.0f, 1.0f); // Right of left face
glEnd();
// Render a quad for the bottom of our pyramid
glBegin(GL_QUADS);
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(-1.0f, -1.0f, 1.0f); // Left/right of front/left face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(1.0f, -1.0f, 1.0f); // Right/left of front/right face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(1.0f, -1.0f, -1.0f); // Right/left of right/back face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(-1.0f, -1.0f, -1.0f); // Left/right of right/back face
glEnd();
glPopMatrix();
glTranslatef(3.0f, 0.0f, 0.0f); // Translate right
glPushMatrix(); // Push the current modelview matrix on the matrix stack // Rotate the primitive on all 3 axis
glBegin(GL_QUADS);
// Top face
glColor3f(0.0f, 1.0f, 0.0f); // Green
glVertex3f(1.0f, 1.0f, -1.0f); // Top-right of top face
glVertex3f(-1.0f, 1.0f, -1.0f); // Top-left of top face
glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom-left of top face
glVertex3f(1.0f, 1.0f, 1.0f); // Bottom-right of top face
// Bottom face
glColor3f(1.0f, 0.5f, 0.0f); // Orange
glVertex3f(1.0f, -1.0f, -1.0f); // Top-right of bottom face
glVertex3f(-1.0f, -1.0f, -1.0f); // Top-left of bottom face
glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom-left of bottom face
glVertex3f(1.0f, -1.0f, 1.0f); // Bottom-right of bottom face
// Front face
glColor3f(1.0f, 0.0f, 0.0f); // Red
glVertex3f(1.0f, 1.0f, 1.0f); // Top-Right of front face
glVertex3f(-1.0f, 1.0f, 1.0f); // Top-left of front face
glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom-left of front face
glVertex3f(1.0f, -1.0f, 1.0f); // Bottom-right of front face
// Back face
glColor3f(1.0f, 1.0f, 0.0f); // Yellow
glVertex3f(1.0f, -1.0f, -1.0f); // Bottom-Left of back face
glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom-Right of back face
glVertex3f(-1.0f, 1.0f, -1.0f); // Top-Right of back face
glVertex3f(1.0f, 1.0f, -1.0f); // Top-Left of back face
// Left face
glColor3f(0.0f, 0.0f, 1.0f); // Blue
glVertex3f(-1.0f, 1.0f, 1.0f); // Top-Right of left face
glVertex3f(-1.0f, 1.0f, -1.0f); // Top-Left of left face
glVertex3f(-1.0f, -1.0f, -1.0f); // Bottom-Left of left face
glVertex3f(-1.0f, -1.0f, 1.0f); // Bottom-Right of left face
// Right face
glColor3f(1.0f, 0.0f, 1.0f); // Violet
glVertex3f(1.0f, 1.0f, 1.0f); // Top-Right of left face
glVertex3f(1.0f, 1.0f, -1.0f); // Top-Left of left face
glVertex3f(1.0f, -1.0f, -1.0f); // Bottom-Left of left face
glVertex3f(1.0f, -1.0f, 1.0f); // Bottom-Right of left face
glEnd();
glPopMatrix();
glTranslatef(-1.5f, -3.0f, 0.0f); // Back to center and lower screen
glPushMatrix();
glColor3f(1.0f, 1.0f, 0.0f); // Yellow
glutSolidSphere(1.0f, 16, 16); // Use GLUT to draw a solid sphere
glScalef(1.01f, 1.01f, 1.01f);
glColor3f(1.0f, 0.0f, 0.0f); // Red
glutWireSphere(1.0f, 16, 16); // Use GLUT to draw a wireframe sphere
glPopMatrix();
}
void initGlut(int argc, char* argv[]) {
std::cout << "Initialise OpenGL..." << std::endl;
glutInit(&argc, argv);
int iScreenWidth = glutGet(GLUT_SCREEN_WIDTH);
int iScreenHeight = glutGet(GLUT_SCREEN_HEIGHT);
glutInitDisplayMode(GLUT_RGBA | GLUT_ALPHA | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowPosition(120, 120);
glutInitWindowSize(600, 600);
glutCreateWindow("OpenGL");
// Register GLUT callbacks
glutDisplayFunc(render);
// Setup initial GL State
glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
glClearDepth(1.0f);
glShadeModel(GL_SMOOTH);
glutMainLoop();
std::cout << "Initialise OpenGL: Success!" << std::endl;
}
int _tmain(int argc, char* argv[])
{
initGlut(argc, argv);
return 0;
}
希望有经验的人会让我知道我错过了哪些显而易见的东西。
答案 0 :(得分：3)
以下是我如何调试问题“OpenGL没有绘制任何东西”：
将此代码添加到render()函数的开头：glClearColor (1, 1, 0, 1); glClear (GL_COLOR_BUFFER_BIT);如果输出变为黄色，则调用render()函数并正确清除输出。然后，您可以删除该代码或将其注释掉。如果输出没有变黄，那么你的render()函数没有被调用，或者它被调用，但你的OpenGL状态被设置为不抽取到屏幕。 （也许当时错误的背景是当前的，或者当前FBO的颜色附件不是你想象的那样。）
尝试绘制一个没有纹理或着色器的白色三角形，以原点为中心。如果它出现，那么您尝试绘制的其他几何图形可能是错误的。如果它没有显示，问题可能是你的矩阵计算（投影或模型视图矩阵）。 （您是否将“相机”指向您认为的位置？您的物体是在您想到的地方绘制的吗？）它也可以是照明，混合或深度测试。为了确保这一点，我把所有这些都关掉了。 （请参阅glEnable() / glDisable()了解如何开启和关闭它们。）
如果这些东西有效，我会开始打开上面关闭的东西：纹理，着色器，灯光，混合，深度测试。我一次打开一个，直到出现问题。
如果没有出错，那么我的对象的几何图形可能是错误的。