在GLSL中使用多个textures+filters

Question

我正在尝试在Opengl中沿着特定的路径呈现点精灵。我将精灵定义为2D纹理，并将其设置为使用GL_NEAREST作为mag/min滤镜。我还定义了一个包含一些2D坐标的1D纹理(这样我只需要每个sprite一个浮点来确定它们的屏幕空间位置)，我将其设置为GL_LINEAR。

然而，当我在我的笔记本电脑上运行我的程序时，它总是使用sprite-texture的mag filter方法，而忽略了path-texture上的设置。我的笔记本电脑在英特尔Iris Pro5200上运行Linux+mesa 9.2.1+Opengl 3.0。我的桌面运行Linux，使用opengl 4.2专有的Nvidia驱动程序，一切工作正常。

相关代码为

//A path "t -> (x,y)" along which we will place our sprites
v2f path[] = {{-0.5,0.5},
    {-0.5,-0.5},
    {0.5,-0.5},
    {0.5,0.5}};
glActiveTexture(GL_TEXTURE0);
if(glGetError() != GL_NO_ERROR)
 report(FAIL, "Couldn't activate texture!");

GLuint pathTex;
glGenTextures(1, &pathTex); //create a new texture
glBindTexture(GL_TEXTURE_1D, pathTex); //start using it as a 1D texture
//store the coordinates of path in the texture so that we can interpolate our path in the shader.
glTexImage1D(GL_TEXTURE_1D,0,GL_RG32F, sizeof(path)/sizeof(v2f),0,GL_RG,GL_FLOAT,path); 
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_BASE_LEVEL, 0);//We need these two lines
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAX_LEVEL, 0);//because we don't have mipmaps.
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);//We want the path to be linearly filtered
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);//Set the min filter just to be safe.
if(glGetError() != GL_NO_ERROR)
 report(FAIL, "Something went wrong setting up pathTex");
GLint uniformLoc = glGetUniformLocation(shaderProgram, "pathTexture"); //locate the uniform
uniformLoc >= 0?glUniform1i(uniformLoc, 0):report(FAIL, "found uniform spriteTexture at %d", uniformLoc); //and set it to "0" because we're using GL_TEXTURE0
  if(glGetError() != GL_NO_ERROR)
    report(FAIL, "Couldn't set uniform!");
  report(PASS, "Setup texture for path");

//create and set second texture
  rgba sprite[] = {{1.0,0,0,1},{0,1.0,0,1},{0,0,1.0,1},{1,1,0,1}}; //our sprite, a simple "red,green,blue,yellow" square.
  glActiveTexture(GL_TEXTURE0+1); //use texUnit 1 now.
  if(glGetError() != GL_NO_ERROR)
    report(FAIL, "Couldn't activate texture!");
  GLuint spriteTex;
  glGenTextures(1, &spriteTex); //create a new texture
  glBindTexture(GL_TEXTURE_2D, spriteTex); //start using it as a 2D texture
  glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA, 2,2,0,GL_RGBA,GL_FLOAT,sprite); //load the data again. 2x2 sprite.
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);//We need these two lines
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);//because we don't have mipmaps.
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);//We want our sprites to be filtered to
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);//the nearest pixel, not interpolated.
  if(glGetError() != GL_NO_ERROR)
    report(FAIL, "Something went wrong setting up pathTex");
  uniformLoc = glGetUniformLocation(shaderProgram, "spriteTexture"); //locates and set the second sampler.
  uniformLoc >= 0?glUniform1i(uniformLoc, 1):report(FAIL, "found uniform spriteTexture at %d", uniformLoc);
  if(glGetError() != GL_NO_ERROR)
    report(FAIL, "Couldn't set uniform!");
  report(PASS, "Setup texture for sprite");

我的顶点着色器是

#version 130
uniform sampler1D pathTexture;
in float t;
void main(){
  gl_Position = texture(pathTexture, t);
}

我的片段着色器是

#version 130
uniform sampler2D spriteTexture;
out vec4 outputColor;
void main()
{
      outputColor = texture(spriteTexture, gl_PointCoord);
}

我粘贴的here和here的全部代码(单个文件)分别是我在Nvidia和英特尔上看到的截图。

编辑:我在Nvidia上得到了与3.0上下文相同的结果。

是什么导致了这种情况？

Answer 1

确保在调用任何其他GLFW函数之前调用glfwInit()

glewInit()也是如此。