Question

我已经阅读了一段时间用于纹理地形的不同技术并遇到了texture splatting。我发现了很多文章讨论如何在OpenGL中做到这一点，但大多数文章只是在理论上讨论它，并提供很少甚至没有我可以研究的代码。有谁知道/有一些代码在OpenGL中说明了这一点？

为了澄清，我希望能够加载四种不同的纹理，并根据四边形/顶点的高度，将纹理从一个渐变到下一个。

编辑：下面是一些代码，以帮助展示我想知道的内容

#include <windows.h>
#include <SFML/Graphics.hpp>
#include <gl/gl.h>
#include <gl/glu.h>

#define GL_CLAMP_TO_EDGE 0x812F

class Scene {
public:
    void resize( int w, int h ) {
        // OpenGL Reshape
        glViewport( 0, 0, w, h );
        glMatrixMode( GL_PROJECTION );
        glLoadIdentity();
        gluPerspective( 120.0, (GLdouble)w/(GLdouble)h, 0.5, 500.0 );
        glMatrixMode( GL_MODELVIEW );
    }
};

int main() {

    sf::RenderWindow window(sf::VideoMode(800, 600, 32), "Test");

    ///Setup the scene, materials, lighting
    Scene scene;
    scene.resize(800,600);
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glColorMaterial(GL_FRONT_AND_BACK, GL_EMISSION);
    glEnable(GL_COLOR_MATERIAL);
    glShadeModel(GL_SMOOTH);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glEnable(GL_LIGHT0);
    float XL = .5, YL = .1, ZL = 1;
    GLfloat ambientLight[] = { 0.2f, 0.2f, 0.2f, 1.0f };
    GLfloat diffuseLight[] = { 0.8f, 0.8f, 0.8, 1.0f };
    GLfloat specularLight[] = { 0.5f, 0.5f, 0.5f, 1.0f };
    GLfloat lightpos[] = {XL, YL, ZL, 0.};
    glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight);
    glLightfv(GL_LIGHT0, GL_SPECULAR, specularLight);
    glLightfv(GL_LIGHT0, GL_POSITION, lightpos);

    ///Test terrain texture splatting

    ///Load the textures
    sf::Image tex1;
    tex1.loadFromFile("texture1.png");
    sf::Image tex2;
    tex2.loadFromFile("texture2.png");

    ///Set the first texture
    GLuint grass;
    glGenTextures(1, &grass);
    glBindTexture(GL_TEXTURE_2D, grass);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex1.getSize().x, tex1.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex1.getPixelsPtr() );

    ///Set the second texture
    GLuint dirt;
    glGenTextures(1, &dirt);
    glBindTexture(GL_TEXTURE_2D, dirt);
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex2.getSize().x, tex2.getSize().y, 0, GL_RGBA, GL_UNSIGNED_BYTE, (const GLvoid*)tex2.getPixelsPtr() );

    ///Start loop
    while( window.isOpen() ) {
        sf::Event event;
        while( window.pollEvent( event ) ) {
            if( event.type == sf::Event::Closed )
                window.close();
        }

        ///Clear buffer and set camera
        glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
        glMatrixMode(GL_PROJECTION);
        glLoadIdentity();
        gluPerspective(50.0, 1.0, 1.0, 50);
        glMatrixMode(GL_MODELVIEW);
        glLoadIdentity();
        gluLookAt(1, 0, 1, 0, 0, 0, 0, 1, 0);

        ///Begin rendering quad             
        glEnable(GL_TEXTURE_2D);
        glBindTexture(GL_TEXTURE_2D, grass);
        ///I know that around here I should enable blending in order to get my two textures to mix, but I am not certain
        glBegin(GL_QUADS);

            glTexCoord2f(0, 0);
            glVertex3f(-0.5, -0.5, 0.0);

            glTexCoord2f(1, 0);
            glVertex3f(-0.5, 0.5, 0.0);

            glTexCoord2f(1, 1);
            glVertex3f(0.5, 0.5, 0.0);

            glTexCoord2f(0, 1);
            glVertex3f(0.5, -0.5, 0.0);
        glEnd();

        ///Reset env settings for SFML
        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

        window.display();
    }
    return 1;
}

Answer 1

如上所述，使用可编程管道，使用着色器。在片段着色器中，您可以根据从顶点着色器接收的顶点数据传递所有纹理并在它们之间进行插值。

快速搜索给了我this result。我相信这就是你所需要的。另请查看this post。 this论文很好地解释了这项技术。

如何在OpenGL中实现Texture Splatting？

1 个答案: