我正在尝试将多个纹理绑定到片段着色器中的采样器。加载代码似乎运行良好。 ATI的CodeXL显示正确加载的纹理。
但是，当我将模型的纹理绑定到Active纹理0和1时，我无法将其发送到我的着色器。当我将着色器制服标记为usampler2D并使用uvec4存储颜色时，就像我应该将纹理作为无符号字节提供一样，我得到一个全白模型。当我将着色器均匀更改为sampler2D并使用vec4存储颜色时，我的glUniform1i调用无法再获取着色器变量的位置，因此没有为活动纹理设置任何内容。这导致可以使用漫反射纹理，但我无法获得正常纹理。从好的方面来说，漫反射纹理就是以这种方式在模型上绘制的。
我不确定问题是什么。我在线检查了几个地方试图解决这个问题，我查看了红皮书。我知道我错过了一些东西，或者说某些状态设置错了，但我似乎无法找到它。提前感谢您提供解决此问题的任何帮助。
int[] testWidth;
testWidth = new int[1];
testWidth[0] = 1000;
// First bind the texture.
bind();
// Make sure that textures are enabled.
// I read that ATI cards need this before MipMapping.
glEnable(GL_TEXTURE_2D);
// Test to make sure we can create a texture like this.
glTexImage2D(GL_PROXY_TEXTURE_2D, 0, format, width, height,
0, format, GL_UNSIGNED_BYTE, null);
glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0, GL_TEXTURE_WIDTH,
testWidth);
if (testWidth[0] == 0)
{
message("Could not load texture onto the graphics card.");
}
else
{
// Not so sure about this part....but it seems to work.
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
// Load the texture data.
glTexImage2D(texture_type, 0, format, width, height,
0, format, GL_UNSIGNED_BYTE, (GLvoid[]?)value);
// Smaller mipmaps need linear mipmap coords.
// Larger just uses linear of the main texture.
glTexParameterf(texture_type, GL_TEXTURE_MIN_FILTER,
GL_LINEAR_MIPMAP_LINEAR);
glTexParameterf(texture_type, GL_TEXTURE_MAG_FILTER,
GL_LINEAR);
// Clamp the texture to the edges.
glTexParameterf(texture_type, GL_TEXTURE_WRAP_S,
GL_CLAMP_TO_EDGE);
glTexParameterf(texture_type, GL_TEXTURE_WRAP_T,
GL_CLAMP_TO_EDGE);
glTexParameterf(texture_type, GL_TEXTURE_WRAP_R,
GL_CLAMP_TO_EDGE);
// Generate the mipmaps. The tex parameter is there
// for ATI cards. Again, it's something I read online.
glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
glGenerateMipmap(texture_type);
}
// Now unbind the texture.
unbind();
if (currentShader != null)
{
currentShader.set_uniform_matrix("model_matrix", ref model_matrix,
true);
if (material != null)
{
if (material.diffuse_texture != null)
{
glActiveTexture(GL_TEXTURE0);
material.diffuse_texture.bind();
currentShader.set_uniform_texture("diffuse_texture",
Constants.DIFFUSE_TEXTURE);
if (material.normal_testure != null)
{
glActiveTexture(GL_TEXTURE1);
material.normal_texture.bind();
currentShader.set_uniform_texture("normal_texture",
Constants.NORMAL_TEXTURE);
}
}
}
// If there is a renderable then render it.
if (renderable != null)
{
renderable.render(1.0);
}
if (material != null)
{
material.unbind();
}
#version 400 core
/**
* Smooth the inward vertex color. Smooth it so that the fragments
* which will be in between the vertices as well can get a value close
* to where they are positioned after being rasterized.
*/
smooth in vec4 vertex_color;
/**
* Smooth the inward texture coordinates. Smooth it so that the
* fragments which will be in between the vertices as well can get a
* value close to where they are positioned after being rasterized.
*/
smooth in vec2 out_texture_coordinate;
/**
* The color to make this fragment.
*/
out vec4 frag_color;
/**
* The models diffuse texture. This will be mapped to index 0.
*/
uniform usampler2D diffuse_texture;
/**
* The models normal texture. This will be mapped to index 1.
*/
uniform usampler2D normal_texture;
/**
* The starting function of the shader.
*/
void main(void)
{
uvec4 diffuseColor;
uvec4 normalModifier;
diffuseColor = texture(diffuse_texture, out_texture_coordinate);
normalModifier = texture(normal_texture, out_texture_coordinate);
// Discard any fragments that have an alpha color less than 0.05.
if (diffuseColor.a < 1.0)
{
// This works as part of depth testing to remove the fragments that
// are not useful.
discard;
}
frag_color = diffuseColor;
}
/**
* Sets the uniform value for a texture in the shader.
*
* @param name The name of the uniform to bind this texture to.
* This must have already been registered.
*
* @param textureUnit The id for the texture unit to bind to the uniform.
* This is not the texture's id/reference, but the OpenGL texture unit
* that the reference is bound to.
* This is set by calling glActiveTexture.
*/
public void set_uniform_texture(string name, int textureUnit)
{
// Check to make sure the uniform was given a location already.
if (register_uniform(name) == true)
{
// Set the data for this uniform then.
glUniform1i(uniform_mapping.get(name), textureUnit);
}
else
{
message("Texture was not set. %s", name);
}
}
/**
* Register a uniform for passing data to the shader program.
*
* @return true if the uniform was found with a valid location;
* otherwise, false.
*
* @param name The name for the parameter to get a uniform location for.
* Use this name for the variable in your shader.
*/
public bool register_uniform(string name)
{
int location;
// Make sure we didn't already get the location of the uniform value.
if (uniform_mapping.has_key(name) == false)
{
location = Constants.OPENGL_INVALID_INDEX;
// We have no information about this uniform, so try
// to get it's location.
location = glGetUniformLocation(reference, name);
// The location will 0 or higher if we found the uniform.
if (location != Constants.OPENGL_INVALID_INDEX)
{
uniform_mapping.set(name, location);
return true;
}
}
else
{
// The uniform was previously found and can be used.
return true;
}
debug("Uniform %s not found!!!!!", name);
return false;
}
答案 0 :(得分：4)
将内部格式设置为GL_RGB / A意味着您应该使用sampler2D而不是usampler2D，即使原始图像数据最初是作为无符号字节给出的。 EDIT 在调用glTexImage2D时，给定的数据被转换为内部格式（在这种情况下，GL_RGBA是每个通道8位，因此不必多发生）。但是，对于大多数图形应用程序而言，需要更高精度的数据，例如，使用非“最近”插值对纹理进行采样时，这就是它通常作为浮点显示的原因。
绑定多个纹理......
glActiveTexture(GL_TEXTURE0 + firstTextureIndex); //firstTextureIndex should be unique amongst the textures bound for a particular shader
glBindTexture(GL_TEXTURE_2D, myFirstTextureHandle);
glUniform1i(glGetUniformLocation(shaderProgramHandle, "firstSampler"), firstTextureIndex); //note the same index given in the glActiveTexture call. This is also always glUniform1i
并重复secondTextureIndex，mySecondTextureHandle，“secondSampler”等。
如果glGetUniformLocation没有返回位置，请仔细检查您是否实际使用它并且它会影响着色器输出（或者它会完全优化）。还要检查通常的拼写错误或缺少“统一”关键字等。
答案 1 :(得分：2)
由于您没有显示Constants的定义，请确保代码的以下断言：
if (material.diffuse_texture != null)
{
glActiveTexture(GL_TEXTURE0);
material.diffuse_texture.bind();
assert(Constants.DIFFUSE_TEXTURE + GL_TEXTURE0 == GL_TEXTURE0);
currentShader.set_uniform_texture("diffuse_texture",
Constants.DIFFUSE_TEXTURE);
if (material.normal_testure != null)
{
glActiveTexture(GL_TEXTURE1);
material.normal_texture.bind();
assert(Constants.NORMAL_TEXTURE + GL_TEXTURE0 == GL_TEXTURE1);
currentShader.set_uniform_texture("normal_texture",
Constants.NORMAL_TEXTURE);
}
一个常见的误解是传递给采样器统一的值是给glActiveTexture的枚举值。实际上，glActiveTexture将GL_TEXTURE0作为偏移基值。