openGL 单通道纹理总是采样 0

Question

我正在尝试使用 freetype 在屏幕上呈现字体。为此，我实现了单通道纹理，但它总是采样 0。

cpp

unsigned char *blankData = new unsigned char[8 * 8];
for(int i = 0; i < 8 * 8; i++){
    blankData[i] = 126;
}
    
glActiveTexture(GL_TEXTURE0);

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

GLuint m_texture2D;
glGenTextures(1, &m_texture2D);
glBindTexture(GL_TEXTURE_2D, m_texture2D);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RED, 8, 8, 0, GL_RED, GL_UNSIGNED_BYTE, blankData);

glUniform1i(glGetUniformLocation(m_program, "texture2D"), 0);

checkGLError();

glGetError() returns GL_NO_ERROR

片段着色器

#version 330 core

in vec2 texCoord;
in vec4 color;

uniform sampler2D texture2D;
out vec4 outColor;


void main()
{
    vec4 texColor = texture(texture2D, texCoord);
    outColor = vec4(texColor.r, texColor.r, texColor.r, 1.0f);

}

结果

ff00ff: 颜色清晰

黑色：片段着色器输出纹理坐标 bottomLeft(0, 0) 到 topRight(1, 1)

Answer 1

如果您不生成 mipmaps (with glGenerateMipmap)，设置 GL_TEXTURE_MIN_FILTER 很重要。由于默认过滤器是 GL_NEAREST_MIPMAP_LINEAR，如果您不将最小化函数更改为 GL_NEAREST 或 GL_LINEAR.

，则纹理将是“Mipmap Incomplete”

glBindTexture(GL_TEXTURE_2D, m_texture2D);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

openGL 单通道纹理总是采样 0

openGL single channel texture always samples 0

c++

opengl

alpha