基本的OpenGL渲染有問題嗎？
[英]Issues with basic OpenGL rendering?
問題描述
我是OpenGL的完整初學者，只是想學習（目前從freeglut開始）。 到目前為止，我具有以下應繪制一些基本3D對象的代碼。 問題是無論我放入render函數（盡管它確實執行），它只會顯示一個空白窗口。
#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;
}
希望有更多經驗的人會讓我知道我所缺少的明顯東西。
1 個解決方案
解決方案1
3 已采納 2013-12-29 01:51:14
這是我調試“ OpenGL沒有繪制任何東西”問題的方法：
將此代碼添加到我的
render()函數的glClearColor (1, 1, 0, 1); glClear (GL_COLOR_BUFFER_BIT);：glClearColor (1, 1, 0, 1); glClear (GL_COLOR_BUFFER_BIT);glClearColor (1, 1, 0, 1); glClear (GL_COLOR_BUFFER_BIT);如果輸出變為黃色，則表示正在調用render()函數並正確清除輸出。 然后，您可以刪除該代碼或將其注釋掉。 如果輸出沒有變為黃色，則說明沒有調用render()函數，或者調用了它，但是將OpenGL狀態設置為不繪制到屏幕上。 （也許當時的上下文不正確，或者當前FBO的顏色附件不是您認為的那樣。）嘗試以原點為中心繪制沒有紋理或着色器的單個白色三角形。 如果顯示出來，則您嘗試繪制的其他幾何圖形可能是錯誤的。 如果未顯示，則問題可能出在矩陣計算（投影或模型視圖矩陣）上。 （您是否將“相機”指向您認為的位置？是否在您想像的位置繪制了對象？）它也可能是照明，混合或深度測試。 為了確定這種測試，我將所有這些功能都關閉了。 （有關如何打開和關閉它們的信息，請參見
glEnable()/glDisable()。）如果這些東西行得通，我便開始打開上面關閉的東西：紋理，着色器，照明，混合，深度測試。 我一次將它們打開，直到出現問題。
如果沒有錯誤，則可能是我的對象的幾何形狀錯誤。
openGL 索引渲染問題
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