移动纹理OpenGL ES 2.0

Question

我正在尝试在OpenGL ES 2.0中实现8列8行的精灵
我出现了第一个图像，但是我不知道如何在OpenGL ES 2.0中转换纹理矩阵，相当于我正在寻找的OpenGL 1.0中的代码

        gl.glMatrixMode(GL10.GL_TEXTURE);
        gl.glLoadIdentity();
        gl.glPushMatrix();
        gl.glTranslatef(0.0f, 0.2f, 0f);
        gl.glPopMatrix();

这是我正在使用atm的矩阵

/**
 * Store the model matrix. This matrix is used to move models from object space (where each model can be thought
 * of being located at the center of the universe) to world space.
 */
private float[] mModelMatrix = new float[16];

/**
 * Store the view matrix. This can be thought of as our camera. This matrix transforms world space to eye space;
 * it positions things relative to our eye.
 */
private float[] mViewMatrix = new float[16];

/** Store the projection matrix. This is used to project the scene onto a 2D viewport. */
private float[] mProjectionMatrix = new float[16];

/** Allocate storage for the final combined matrix. This will be passed into the shader program. */
private float[] mMVPMatrix = new float[16];

/** 
 * Stores a copy of the model matrix specifically for the light position.
 */
private float[] mLightModelMatrix = new float[16];  

我的顶点着色器

uniform mat4 u_MVPMatrix;       // A constant representing the combined     model/view/projection matrix.                  
uniform mat4 u_MVMatrix;        // A constant representing the combined model/view matrix.              

attribute vec4 a_Position;      // Per-vertex position information we will pass in.                             
attribute vec3 a_Normal;        // Per-vertex normal information we will pass in.      
attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in.       

varying vec3 v_Position;        // This will be passed into the fragment shader.                            
varying vec3 v_Normal;          // This will be passed into the fragment shader.  
varying vec2 v_TexCoordinate;   // This will be passed into the fragment shader.            

// The entry point for our vertex shader.  
void main()                                                     
{                                                         
    // Transform the vertex into eye space.     
    v_Position = vec3(u_MVMatrix * a_Position);                 

    // Pass through the texture coordinate.
    v_TexCoordinate = a_TexCoordinate;                                      

    // Transform the normal's orientation into eye space.
    v_Normal = vec3(u_MVMatrix * vec4(a_Normal, 0.0));

    // gl_Position is a special variable used to store the final position.
    // Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
    gl_Position = u_MVPMatrix * a_Position;                               
}

我的片段着色器：

precision mediump float;        // Set the default precision to medium. We don't need as high of a 
                            // precision in the fragment shader.
    uniform vec3 u_LightPos;        // The position of the light in eye space.
    uniform sampler2D u_Texture;    // The input texture.

    varying vec3 v_Position;        // Interpolated position for this fragment.
    varying vec3 v_Normal;          // Interpolated normal for this fragment.
    varying vec2 v_TexCoordinate;   // Interpolated texture coordinate per fragment.

    // The entry point for our fragment shader.
    void main()                         
    {                              
        // Will be used for attenuation.
      float distance = length(u_LightPos - v_Position);                  

        // Get a lighting direction vector from the light to the vertex.
     vec3 lightVector = normalize(u_LightPos - v_Position);                 

        // Calculate the dot product of the light vector and vertex normal. If the normal and light vector are
        // pointing in the same direction then it will get max illumination.
     float diffuse = max(dot(v_Normal, lightVector), 0.0);                                                                                

        // Add attenuation. 
     diffuse = diffuse * (1.0 / (1.0 + (0.25 * distance)));

     // Add ambient lighting
     diffuse = diffuse + 0.7;  

        // Multiply the color by the diffuse illumination level and texture value to get final output color.
     gl_FragColor = (diffuse * texture2D(u_Texture, v_TexCoordinate));                                          
     }                                                                      

Answer 1

您将需要自己对纹理坐标进行转换，可以在以下四个位置之一进行：

• 将转换应用于原始模型数据。
• 在CPU中应用转换（除非您有充分的理由，否则不建议这样做，因为这是顶点着色器的作用）。
• 在顶点着色器中应用变换（推荐）。
• 在片段着色器中应用转换。

如果要对纹理坐标应用平移，最灵活的方法是使用数学库创建平移矩阵并将新矩阵均匀地传递到顶点着色器（与传递mMVPMatrix和mLightModelMatrix的方法相同） ）。 然后，您可以将转换矩阵乘以顶点着色器中的纹理坐标，并将结果输出为变化的向量。

顶点着色器：

texture_coordinate_varying = texture_matrix_uniform * texture_coordinate_attribute;

片段着色器：

gl_FragColor = texture2D(texture_sampler, texture_coordinate_varying);

请注意：您的GLES 1.0代码实际上没有执行翻译，因为您将其包围了推入式弹出式操作。