的OpenGL ES 2.0：渲染紋理屏幕沒有模型視圖或投影矩陣

Question

我試圖渲染貼圖到屏幕的左下角，所以像：

glViewPort(0, 0, width/4, height/4); 

我有執行該渲染的麻煩。我畫一個四邊形，做一些基本的東西。我已經試過渲染的所有變體爲在這些鏈接和其他人討論SO四：

How to draw a texture as a 2D background in OpenGL ES 2.0?

OpenGL ES 2.0 Rendering with a Texture

我的頂點和片段着色器如下：

const char * VERTEX_SHADER = 
"            \n\ 
attribute vec4 a_position;      \n\ 
attribute vec4 a_texCoord;      \n\ 
               \n\ 
               \n\ 
#ifdef GL_ES         \n\ 
varying mediump vec2 v_texCoord;    \n\ 
#else           \n\ 
varying vec2 v_texCoord;      \n\ 
#endif           \n\ 
               \n\ 
void main()          \n\ 
{            \n\ 
    gl_Position = a_position;     \n\ 
    v_texCoord = a_texCoord.xy;     \n\ 
}            \n\ 
"; 


const char * FRAGMENT_SHADER = 
"              \n\ 
#ifdef GL_ES           \n\ 
precision lowp float;         \n\ 
#endif             \n\ 
                 \n\ 
varying vec2 v_texCoord;        \n\ 
uniform sampler2D u_texture;       \n\ 
                 \n\ 
void main()            \n\ 
{              \n\ 
    gl_FragColor = texture2D(u_texture, v_texCoord); \n\ 
}              \n\ 
"; 

而我的渲染代碼是這樣的：

static const GLfloat squareVertices[] = { 
    -1.0f, -1.0f, 
    1.0f, -1.0f, 
    -1.0f, 1.0f, 
    1.0f, 1.0f, 
}; 

static const GLfloat textureVertices[] = { 
    0.0f, 0.0f, 
    1.0f, 0.0f, 
    0.0f, 1.0f, 
    1.0f, 1.0f, 
}; 


// ... 

glUseProgram(myProgram_); 
glBindFramebuffer(GL_FRAMEBUFFER, framebuffer); 
glViewPort(0, 0, width/4, height/4); // width and height are defined elsewhere 

glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D, myTexture_); // myTexture_ has been successfully loaded and checked 

// Update uniform values 
glUniform1i(textureUniformLocation_, 0); 

// Update attribute values. 
glEnableVertexAttribArray(a_position_location_); 
glEnableVertexAttribArray(a_texcoord_location_); 
glVertexAttribPointer(a_position_location_, 2, GL_FLOAT, 0, 0, squareVertices); 
glVertexAttribPointer(a_texcoord_location_, 2, GL_FLOAT, 0, 0, textureVertices; 

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); 

頂點和片段着色器編譯並且glProgram鏈接成功。我所得到的只是屏幕左下角的一個白色矩形（當然，在已經渲染的場景的頂部）。我在這裏錯過了什麼嗎？

Answer 1

也許你忘了設置縮小過濾器？將紋理保存爲圖像可能不會提醒您這樣的採樣錯誤。

http://www.opengl.org/wiki/Common_Mistakes#Creating_a_Texture