OpenGL基本顶点着色器

Question

我是着色器概念的新手，我正在尝试在 OpenGL ES 中实现一个 8x8 的精灵。

我想在顶点着色器中移动纹理，但我不知道怎么做，我的代码可能是错误的，请随时纠正我

如果我在顶点着色器中更改这条线，纹理会缩放但我想移动而不是缩放！：

v_TexCoordinate = a_TexCoordinate*vec2(1.5,1.5);

所以我应该申请附加，但我不知道怎么做（也许还有其他方法）

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.              
uniform mat4 u_TextureMatrix;


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;                               
}  

这是我的绘图功能

private void drawMagia()
{
    GLES20.glUseProgram(mMagiaProgramHandle);
    mTextureMatrixHandle = GLES20.glGetUniformLocation(mMagiaProgramHandle, "u_TextureMatrix");
    mMagiaTextureCoordinateHandle = GLES20.glGetAttribLocation(mMagiaProgramHandle, "a_TexCoordinate");



    mMagiaPositions.position(0);        
    GLES20.glVertexAttribPointer(mPositionHandle, mPositionDataSize, GLES20.GL_FLOAT, false,
            0, mMagiaPositions);        

    GLES20.glEnableVertexAttribArray(mPositionHandle);        


    // Pass in the normal information
    mMagiaNormals.position(0);
    GLES20.glVertexAttribPointer(mNormalHandle, mNormalDataSize, GLES20.GL_FLOAT, false, 
            0, mMagiaNormals);

    GLES20.glEnableVertexAttribArray(mNormalHandle);

    // Pass in the texture coordinate information
    mMagiaTextureCoordinates.position(0);
    GLES20.glVertexAttribPointer(mTextureCoordinateHandle, mTextureCoordinateDataSize, GLES20.GL_FLOAT, false, 
            0, mMagiaTextureCoordinates);

    GLES20.glEnableVertexAttribArray(mTextureCoordinateHandle);

    // This multiplies the view matrix by the model matrix, and stores the
    // result in the MVP matrix
    // (which currently contains model * view).
    Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);

    // Pass in the modelview matrix.
    GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mMVPMatrix, 0);

    GLES20.glUniformMatrix4fv(mTextureMatrixHandle, 1, false, mTextureMatrix, 0);

    // This multiplies the modelview matrix by the projection matrix, and
    // stores the result in the MVP matrix
    // (which now contains model * view * projection).
    Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);

    // Pass in the combined matrix.
    GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

    // Pass in the light position in eye space.
    GLES20.glUniform3f(mLightPosHandle, mLightPosInEyeSpace[0], mLightPosInEyeSpace[1], mLightPosInEyeSpace[2]);


    // Draw the square.
    GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 6);
}

Answer 1

您可以添加一些偏移量而不是相乘。

v_TexCoordinate = a_TexCoordinate + vec2(1.5,1.5);

你的纹理也应该被夹住