在 C++ 中显示无边框透明背景的图像/ OpenGL

Question

我正在寻找一种方法来在透明背景无边框的窗口上显示两个 png 图像（事实上，它将是数字，我的目标是创建一个用于实时流媒体的叠加层以显示玩家得分和一些其他附加内容）。这样我们就可以看到后面窗口上的分数。

有什么办法可以做类似的事情吗？我已经用 SDL、纹理尝试了很多东西，但没有任何结果能让我满意。我发现的最好的结果是一些脏代码几乎可以工作但完全无法使用。

如果可能，该解决方案可以添加这样的功能：当您在 2 个分数之一上向左或向右单击时，它会增加或减少。

编辑：这是我当前的代码。我开始新的工作，没有任何以前的脏代码，因为我想了解我在做什么。我将 2 个数字显示为纹理，现在我想删除窗口的边框和标题栏，并使背景透明。

#include <stdio.h>
#include <stdlib.h>

#include <iostream>
#include <windows.h>
#include <windowsx.h>
#include <math.h>

#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>

#include "sdlglutils.h"

#include <assert.h>
#include <tchar.h>

using namespace std;

int overlay;
int TimerEnabled;
GLfloat posX, posY, posZ;
GLuint texture_0, texture_1, texture_2, texture_3;

void Initialize()
{
    glEnable(GL_ALPHA_TEST);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_COLOR_MATERIAL);

    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glClearColor(0, 0, 0, 0);

    glEnable(GL_TEXTURE_2D);
}

void Reshape(int w, int h)
{
    glViewport(0, 0, (GLsizei) w, (GLsizei) h);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45.0f, (GLfloat)w/(GLfloat)h,0.1f,100.0f);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    texture_0 = loadTexture("0.png");
    texture_1 = loadTexture("1.png");
    texture_2 = loadTexture("2.png");
    texture_3 = loadTexture("3.png");

    return;
}

void Draw()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    glTranslatef(posX,posY,posZ);

    glScalef(1.0f,1.0f,1.0f);
    glPushMatrix();
        glTranslated(-6, 8, 0);
        glBindTexture(GL_TEXTURE_2D, texture_1);
        glBegin(GL_QUADS);
            glTexCoord2d(0,0);      glVertex2d(0,0);
            glTexCoord2d(1,0);      glVertex2d(1,0);
            glTexCoord2d(1,1);      glVertex2d(1,1);
            glTexCoord2d(0,1);      glVertex2d(0,1);
        glEnd();
    glPopMatrix();

    glPushMatrix();
        glTranslated(6, 8, 0);
        glBindTexture(GL_TEXTURE_2D, texture_2);
        glBegin(GL_QUADS);
            glTexCoord2d(0,0);      glVertex2d(0,0);
            glTexCoord2d(1,0);      glVertex2d(1,0);
            glTexCoord2d(1,1);      glVertex2d(1,1);
            glTexCoord2d(0,1);      glVertex2d(0,1);
        glEnd();
    glPopMatrix();

    glFlush();
}

void Display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLoadIdentity();
    Draw();

    glutSwapBuffers();
}

void KeyboardSpecialEvent( int key, int x, int y)
{
    switch(key)
    {
        case(GLUT_KEY_UP) :
        {
            posY += 0.3;
        }break;

        case(GLUT_KEY_DOWN) :
        {
            posY -= 0.3;
        }break;

        case(GLUT_KEY_LEFT) :
        {
            posX -= 0.3;
        }break;

        case(GLUT_KEY_RIGHT) :
        {
            posX += 0.3;
        }break;
    }
}
void MouseEvent( int button, int state, int x, int y){ };
void MotionMouseEvent( int x, int y ){  };
void IdleEvent(){  };
void TimerEvent(int time)
{
    glutPostRedisplay();

    if(TimerEnabled)
        glutTimerFunc(10, TimerEvent, time);
}

void KeyboardEvent( unsigned char key, int x, int y)
{
    switch(key)
    {
        case ' ' :
        {
            TimerEnabled = !TimerEnabled;
            if (TimerEnabled)
                glutTimerFunc(40, TimerEvent, 0);
        }
        break;

        case 'q' :
        {
            exit(0);
        }
        break;
    }
}

int main(int argc, char** argv)
{
    posX = 0;
    posY = 0;
    posZ = -25;
    TimerEnabled = 1;

    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGBA);

    glutInitWindowSize(1600,900);
    glutInitWindowPosition(0,0);

    overlay = glutCreateWindow("ScoreOverlay");
    //glutFullScreen();

    Initialize();

    glutDisplayFunc(Display);
    glutReshapeFunc(Reshape);
    glutKeyboardFunc(KeyboardEvent);
    glutSpecialFunc(KeyboardSpecialEvent);
    glutMouseFunc(MouseEvent);
    glutMotionFunc(MotionMouseEvent);
    glutIdleFunc(IdleEvent);
    glutTimerFunc(40, TimerEvent, 0);

    glutMainLoop();

    return 0;
}

Answer 1

这是一个可以帮助您的工作基础示例（使用带有 clr 支持的 c++）。

您需要根据您的需要进行调整（例如使用 DrawImage 而不是 FillEllipse）

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;

ref class MyForm : public Form
{
public:

    MyForm()
    {
        this->m_brush = gcnew SolidBrush(Color::Blue);

        this->m_canvas = gcnew System::Windows::Forms::Panel();
        this->m_canvas->BackColor = Color::Pink;
        this->m_canvas->Dock = System::Windows::Forms::DockStyle::Fill;
        this->m_canvas->Location = System::Drawing::Point(0, 0);
        this->m_canvas->Margin = System::Windows::Forms::Padding(0);
        this->m_canvas->Name = "Canvas";
        this->m_canvas->Paint += gcnew System::Windows::Forms::PaintEventHandler(this, &MyForm::canvas_Paint);
        this->m_canvas->TabIndex = 0;

        this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
        this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
        this->BackColor = Color::Pink;
        this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::None;
        this->ClientSize = System::Drawing::Size(200, 200);
        this->Controls->Add(this->m_canvas);
        this->KeyDown += gcnew System::Windows::Forms::KeyEventHandler(this, &MyForm::form_KeyDown);
        this->TransparencyKey = Color::Pink;
        this->Name = "MyForm";
        this->Text = "MyForm";
    }

private:

    void canvas_Paint(Object^ sender, PaintEventArgs^ e) {
        e->Graphics->FillEllipse(this->m_brush, Rectangle(50, 50, 100, 100));
    }

    void form_KeyDown(System::Object^ sender, System::Windows::Forms::KeyEventArgs^ e) {
        // Test key ...
        this->m_canvas->Invalidate();
        // ...
    }

    Brush^ m_brush;
    Panel^ m_canvas;
};

[STAThreadAttribute]
int main(array<System::String ^> ^args)
{
    // Enabling Windows XP visual effects before any controls are created
    Application::EnableVisualStyles();
    Application::SetCompatibleTextRenderingDefault(false); 

    // Create the main window and run it
    Application::Run(gcnew MyForm());
    return 0;
}

Answer 2

看起来您在 Windows 上需要这个。您看过分层Windows吗？

除非您出于某种原因需要 OpenGL 来处理图形，否则我认为您最好将图像作为常规位图加载并直接将它们传输到分层窗口。使用 OpenGL，您需要绘制纹理贴图，然后获取该纹理并将其传输到分层窗口。