Question

我编写了一种方法，可以在设置普通图片的大小时轻松绘制图像，没有问题，但是当您尝试使用Alpha通道图像绘制图像时，图像小于应有的图像。

为了让您更清楚地看到两张图片：

左边的骑士理论上与绿色方块大小相同。

在第二张图片中，您可以清楚地看到它。我不知道问题出在哪里，通常的图像你可以设置问题的大小，但不包括alpha通道。

    @SuppressWarnings("unused")
public class Start {

      float x = 400, y = 300;
    float rotation = 0;

    /** time at last frame */
    long lastFrame;

    /** frames per second */
    int fps;
    /** last fps time */
    long lastFPS;

    /** is VSync Enabled */
    boolean vsync;

    public void start() {
        try {
            Display.setDisplayMode(new DisplayMode(1280, 720));
            Display.create();
        } catch (LWJGLException e) {
            e.printStackTrace();
            System.exit(0);
        }

        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        glOrtho(0, 1280, 720, 0, 1, -1);
        glMatrixMode(GL_MODELVIEW);
        glEnable(GL_TEXTURE_2D);

        getDelta(); // call once before loop to initialise lastFrame
        lastFPS = getTime(); // call before loop to initialise fps timer
        Texture tex = LoadTexture("res/1.png", "PNG");
        Texture t2 = LoadTexture("res/image.png", "PNG");
        Texture t3 = LoadTexture("res/atack1/1.png", "PNG");

        while (!Display.isCloseRequested()) {
            int delta = getDelta();
            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

            update(delta);
            DrawImage(t3, 0, 0, 100, 120);  

                glEnd();

             Display.update();
            Display.sync(60); // cap fps to 60fps
        }

        Display.destroy();
        System.exit(0);
    }

    public void update(int delta) {
        // rotate quad
        rotation += 0.15f * delta;

        if (Keyboard.isKeyDown(Keyboard.KEY_LEFT)) x -= 0.35f * delta;
        if (Keyboard.isKeyDown(Keyboard.KEY_RIGHT)) x += 0.35f * delta;

        if (Keyboard.isKeyDown(Keyboard.KEY_UP)) y -= 0.35f * delta;
        if (Keyboard.isKeyDown(Keyboard.KEY_DOWN)) y += 0.35f * delta;

        while (Keyboard.next()) {
            if (Keyboard.getEventKeyState()) {
                if (Keyboard.getEventKey() == Keyboard.KEY_F) {
                    setDisplayMode(1280, 720, !Display.isFullscreen());
                }
                else if (Keyboard.getEventKey() == Keyboard.KEY_V) {
                    vsync = !vsync;
                    Display.setVSyncEnabled(vsync);
                }
            }
        }

        // keep quad on the screen
        if (x < 0) x = 0;
        if (x > 800) x = 800;
        if (y < 0) y = 0;
        if (y > 600) y = 600;

        updateFPS(); // update FPS Counter
    }

    /**
     * Set the display mode to be used 
     * 
     * @param width The width of the display required
     * @param height The height of the display required
     * @param fullscreen True if we want fullscreen mode
     */
    public void setDisplayMode(int width, int height, boolean fullscreen) {

        // return if requested DisplayMode is already set
                if ((Display.getDisplayMode().getWidth() == width) && 
            (Display.getDisplayMode().getHeight() == height) && 
            (Display.isFullscreen() == fullscreen)) {
            return;
        }

        try {
            DisplayMode targetDisplayMode = null;

            if (fullscreen) {
                DisplayMode[] modes = Display.getAvailableDisplayModes();
                int freq = 0;

                for (int i=0;i<modes.length;i++) {
                    DisplayMode current = modes[i];

                    if ((current.getWidth() == width) && (current.getHeight() == height)) {
                        if ((targetDisplayMode == null) || (current.getFrequency() >= freq)) {
                            if ((targetDisplayMode == null) || (current.getBitsPerPixel() > targetDisplayMode.getBitsPerPixel())) {
                                targetDisplayMode = current;
                                freq = targetDisplayMode.getFrequency();
                            }
                        }

                        // if we've found a match for bpp and frequence against the 
                        // original display mode then it's probably best to go for this one
                        // since it's most likely compatible with the monitor
                        if ((current.getBitsPerPixel() == Display.getDesktopDisplayMode().getBitsPerPixel()) &&
                            (current.getFrequency() == Display.getDesktopDisplayMode().getFrequency())) {
                            targetDisplayMode = current;
                            break;
                        }
                    }
                }
            } else {
                targetDisplayMode = new DisplayMode(width,height);
            }

            if (targetDisplayMode == null) {
                System.out.println("Failed to find value mode: "+width+"x"+height+" fs="+fullscreen);
                return;
            }

            Display.setDisplayMode(targetDisplayMode);
            Display.setFullscreen(fullscreen);

        } catch (LWJGLException e) {
            System.out.println("Unable to setup mode "+width+"x"+height+" fullscreen="+fullscreen + e);
        }
    }

    /** 
     * Calculate how many milliseconds have passed 
     * since last frame.
     * 
     * @return milliseconds passed since last frame 
     */
    public int getDelta() {
        long time = getTime();
        int delta = (int) (time - lastFrame);
        lastFrame = time;

        return delta;
    }

    /**
     * Get the accurate system time
     * 
     * @return The system time in milliseconds
     */
    public long getTime() {
        return (Sys.getTime() * 1000) / Sys.getTimerResolution();
    }

    /**
     * Calculate the FPS and set it in the title bar
     */
    public void updateFPS() {
        if (getTime() - lastFPS > 1000) {
            Display.setTitle("FPS: " + fps);
            fps = 0;
            lastFPS += 1000;
        }
        fps++;
    }

    public void initGL() {
        GL11.glMatrixMode(GL11.GL_PROJECTION);
        GL11.glLoadIdentity();
        GL11.glOrtho(0, 800, 0, 600, 1, -1);
        GL11.glMatrixMode(GL11.GL_MODELVIEW);
    }


    public static void main(String[] argv) {
        Start fullscreenExample = new Start();
        fullscreenExample.start();

    }




     public static void DrawImage(Texture texture,float x,float y, float width, float height){
        if(texture != null){
            texture.bind();

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

                glPixelStorei(GL_UNPACK_ALIGNMENT, 4);

                glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE  );
                glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE  );


            //set transparency
            glColor4f(1, 1, 1,1);
            //
            glTranslatef(x, y, 0);
            glBegin(GL_QUADS);
            glTexCoord2f(0, 0);
            glVertex2f(0, 0);
            glTexCoord2f(1, 0);
            glVertex2f(width, 0);
            glTexCoord2f(1, 1);
            glVertex2f(width, height);
            glTexCoord2f(0, 1);
            glVertex2f(0, height);
            glEnd();
            glLoadIdentity(); 


        }
    }


     public static Texture LoadTexture(String path,String fileType){
        Texture tex = null;
        InputStream in = ResourceLoader.getResourceAsStream(path);
        try {
            tex = TextureLoader.getTexture(fileType, in);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return tex;

    }









}

Answer 1

看起来图像尺寸不同，但您在两个四边形上都应用了完整的0-1 texcoord。这将在您加载纹理时使用纹理的全宽和高度。

解决这个问题的方法是确定骑士精灵实际上有多少像素，并使用它来计算texcoord的0到1之间的值。

例如，如果骑士宽度为60像素且完整图像宽度为100像素，则您的X texcoord将为(60.0f / 100.0f)，即0.6f。对Y轴做同样的事情。

这是一个关于OpenGL纹理的精彩教程，也可以帮助您清除其他一些内容：https://open.gl/textures

在OpenGL中缩放纹理

1 个答案: