GlactiveTexture默认行为未预期
glActiveTexture default behavior not as anticipated
我想对默认的OpenGL行为进行一些澄清。我的理解是,默认的活动纹理单元为0(GL_TEXTURE0
(,除非通过glActiveTexture
明确更改,否则将保持如此。
我之所以问这个,是因为我得到了无法解释的行为,这是有问题的。将纹理加载并绑定到GL_TEXTURE_2D
(假设GL_TEXTURE0
处于活动状态(后,直到将活动纹理设置为GL_TEXTURE1
之前,我无法显示它。即使在加载后首先将其绑定之前,也要明确调用 glActiveTexture(GL_TEXTUREX)
,然后在抽奖期间使用该调用时重复此调用。纹理仅在我在绑定和分配给着色器之前调用glActiveTexture(GL_TEXTURE1)
时显示。
当我尝试使用更多纹理的纹理与我必须明确设置每个glActiveTexture(GL_TEXTURE...)
时,请重复此过程,具体取决于我加载的顺序,并在将纹理绑定并将其绑定并分配给阴影器之前首先绑定纹理。即使我没有加载的第一个纹理绘制,我仍然必须调用glActiveTexture(GL_TEXTURE2)
...而不是GL_TEXTURE1
,甚至更好的GL_TEXTURE0
,因为我什至还没有拨打glActiveTexture(...)
。我认为后者是根据GL规格发生的事情。
https://www.khronos.org/registry/opengl-refpages/gl4/html/glactivetexture.xhtml
这是驾驶员吗?
dell Precision M6800,NV K2200M,GL 4.1&3.3。
更新:隔离示例。
#include <Windows.h>
#include <glGL.h>
#include "glext.h"
#include "wglext.h"
#include <vector>
#include <memory>
#include <atlimage.h>
namespace
{
class GLFunc
{
public:
GLFunc()
{
glCreateProgram = (PFNGLCREATEPROGRAMPROC)wglGetProcAddress("glCreateProgram");
glCreateShader = (PFNGLCREATESHADERPROC)wglGetProcAddress("glCreateShader");
glShaderSource = (PFNGLSHADERSOURCEPROC)wglGetProcAddress("glShaderSource");
glCompileShader = (PFNGLCOMPILESHADERPROC)wglGetProcAddress("glCompileShader");
glAttachShader = (PFNGLATTACHSHADERPROC)wglGetProcAddress("glAttachShader");
glDetachShader = (PFNGLDETACHSHADERPROC)wglGetProcAddress("glDetachShader");
glLinkProgram = (PFNGLLINKPROGRAMPROC)wglGetProcAddress("glLinkProgram");
glUseProgram = (PFNGLUSEPROGRAMPROC)wglGetProcAddress("glUseProgram");
glGenFramebuffers = (PFNGLGENFRAMEBUFFERSPROC)wglGetProcAddress("glGenFramebuffers");
glBindFramebuffer = (PFNGLBINDFRAMEBUFFERPROC)wglGetProcAddress("glBindFramebuffer");
glGenRenderbuffers = (PFNGLGENRENDERBUFFERSPROC)wglGetProcAddress("glGenRenderbuffers");
glBindRenderbuffer = (PFNGLBINDRENDERBUFFERPROC)wglGetProcAddress("glBindRenderbuffer");
glRenderbufferStorage = (PFNGLRENDERBUFFERSTORAGEPROC)wglGetProcAddress("glRenderbufferStorage");
glFramebufferRenderbuffer = (PFNGLFRAMEBUFFERRENDERBUFFERPROC)wglGetProcAddress("glFramebufferRenderbuffer");
glFramebufferTexture = (PFNGLFRAMEBUFFERTEXTUREPROC)wglGetProcAddress("glFramebufferTexture");
glDrawBuffers = (PFNGLDRAWBUFFERSPROC)wglGetProcAddress("glDrawBuffers");
glCheckFramebufferStatus = (PFNGLCHECKFRAMEBUFFERSTATUSPROC)wglGetProcAddress("glCheckFramebufferStatus");
glGenVertexArrays = (PFNGLGENVERTEXARRAYSPROC)wglGetProcAddress("glGenVertexArrays");
glBindBuffer = (PFNGLBINDBUFFERPROC)wglGetProcAddress("glBindBuffer");
glBufferData = (PFNGLBUFFERDATAPROC)wglGetProcAddress("glBufferData");
glDeleteFramebuffers = (PFNGLDELETEFRAMEBUFFERSPROC)wglGetProcAddress("glDeleteFramebuffers");
glDeleteRenderbuffers = (PFNGLDELETERENDERBUFFERSPROC)wglGetProcAddress("glDeleteRenderbuffers");
glDeleteVertexArrays = (PFNGLDELETEVERTEXARRAYSPROC)wglGetProcAddress("glDeleteVertexArrays");
glGetShaderiv = (PFNGLGETSHADERIVPROC)wglGetProcAddress("glGetShaderiv");
glGetShaderInfoLog = (PFNGLGETSHADERINFOLOGPROC)wglGetProcAddress("glGetShaderInfoLog");
glGetProgramiv = (PFNGLGETPROGRAMIVPROC)wglGetProcAddress("glGetProgramiv");
glGetProgramInfoLog = (PFNGLGETPROGRAMINFOLOGPROC)wglGetProcAddress("glGetProgramInfoLog");
glGenBuffers = (PFNGLGENBUFFERSPROC)wglGetProcAddress("glGenBuffers");
glEnableVertexAttribArray = (PFNGLENABLEVERTEXATTRIBARRAYPROC)wglGetProcAddress("glEnableVertexAttribArray");
glVertexAttribPointer = (PFNGLVERTEXATTRIBPOINTERPROC)wglGetProcAddress("glVertexAttribPointer");
glBindVertexArray = (PFNGLBINDVERTEXARRAYPROC)wglGetProcAddress("glBindVertexArray");
glGetUniformLocation = (PFNGLGETUNIFORMLOCATIONPROC)wglGetProcAddress("glGetUniformLocation");
glUniformMatrix2fv = (PFNGLUNIFORMMATRIX2FVPROC)wglGetProcAddress("glUniformMatrix2fv");
glUniformMatrix3fv = (PFNGLUNIFORMMATRIX3FVPROC)wglGetProcAddress("glUniformMatrix3fv");
glUniformMatrix4fv = (PFNGLUNIFORMMATRIX4FVPROC)wglGetProcAddress("glUniformMatrix4fv");
glUniform1f = (PFNGLUNIFORM1FPROC)wglGetProcAddress("glUniform1f");
glUniform2f = (PFNGLUNIFORM2FPROC)wglGetProcAddress("glUniform2f");
glUniform3f = (PFNGLUNIFORM3FPROC)wglGetProcAddress("glUniform3f");
glUniform4f = (PFNGLUNIFORM4FPROC)wglGetProcAddress("glUniform4f");
glUniform1i = (PFNGLUNIFORM1IPROC)wglGetProcAddress("glUniform1i");
glUniform2i = (PFNGLUNIFORM2IPROC)wglGetProcAddress("glUniform2i");
glUniform3i = (PFNGLUNIFORM3IPROC)wglGetProcAddress("glUniform3i");
glUniform4i = (PFNGLUNIFORM4IPROC)wglGetProcAddress("glUniform4i");
glActiveTexture = (PFNGLACTIVETEXTUREPROC)wglGetProcAddress("glActiveTexture");
glDeleteShader = (PFNGLDELETESHADERPROC)wglGetProcAddress("glDeleteShader");
}
PFNGLCREATEPROGRAMPROC glCreateProgram;
PFNGLCREATESHADERPROC glCreateShader;
PFNGLSHADERSOURCEPROC glShaderSource;
PFNGLCOMPILESHADERPROC glCompileShader;
PFNGLATTACHSHADERPROC glAttachShader;
PFNGLDETACHSHADERPROC glDetachShader;
PFNGLLINKPROGRAMPROC glLinkProgram;
PFNGLUSEPROGRAMPROC glUseProgram;
PFNGLGENFRAMEBUFFERSPROC glGenFramebuffers;
PFNGLBINDFRAMEBUFFERPROC glBindFramebuffer;
PFNGLGENRENDERBUFFERSPROC glGenRenderbuffers;
PFNGLBINDRENDERBUFFERPROC glBindRenderbuffer;
PFNGLRENDERBUFFERSTORAGEPROC glRenderbufferStorage;
PFNGLFRAMEBUFFERRENDERBUFFERPROC glFramebufferRenderbuffer;
PFNGLFRAMEBUFFERTEXTUREPROC glFramebufferTexture;
PFNGLDRAWBUFFERSPROC glDrawBuffers;
PFNGLCHECKFRAMEBUFFERSTATUSPROC glCheckFramebufferStatus;
PFNGLGENVERTEXARRAYSPROC glGenVertexArrays;
PFNGLBINDBUFFERPROC glBindBuffer;
PFNGLBUFFERDATAPROC glBufferData;
PFNGLDELETEFRAMEBUFFERSPROC glDeleteFramebuffers;
PFNGLDELETERENDERBUFFERSPROC glDeleteRenderbuffers;
PFNGLDELETEVERTEXARRAYSPROC glDeleteVertexArrays;
PFNGLGETSHADERIVPROC glGetShaderiv;
PFNGLGETSHADERINFOLOGPROC glGetShaderInfoLog;
PFNGLGETPROGRAMIVPROC glGetProgramiv;
PFNGLGETPROGRAMINFOLOGPROC glGetProgramInfoLog;
PFNGLGENBUFFERSPROC glGenBuffers;
PFNGLENABLEVERTEXATTRIBARRAYPROC glEnableVertexAttribArray;
PFNGLVERTEXATTRIBPOINTERPROC glVertexAttribPointer;
PFNGLBINDVERTEXARRAYPROC glBindVertexArray;
PFNGLGETUNIFORMLOCATIONPROC glGetUniformLocation;
PFNGLUNIFORMMATRIX2FVPROC glUniformMatrix2fv;
PFNGLUNIFORMMATRIX3FVPROC glUniformMatrix3fv;
PFNGLUNIFORMMATRIX4FVPROC glUniformMatrix4fv;
PFNGLUNIFORM1FPROC glUniform1f;
PFNGLUNIFORM2FPROC glUniform2f;
PFNGLUNIFORM3FPROC glUniform3f;
PFNGLUNIFORM4FPROC glUniform4f;
PFNGLUNIFORM1IPROC glUniform1i;
PFNGLUNIFORM2IPROC glUniform2i;
PFNGLUNIFORM3IPROC glUniform3i;
PFNGLUNIFORM4IPROC glUniform4i;
PFNGLACTIVETEXTUREPROC glActiveTexture;
PFNGLDELETESHADERPROC glDeleteShader;
};
static HGLRC hglrc_;
static GLFunc* gl_;
unsigned int points_;
unsigned int uvs_;
unsigned int indexes_;
unsigned int vao_;
unsigned int calibrationTexture_;
unsigned int vertexShader_;
unsigned int fragmentShader_;
unsigned int programID_;
struct Vector3
{
Vector3(float x, float y, float z)
: x_(x), y_(y), z_(z)
{
}
float x_;
float y_;
float z_;
};
struct Vector2
{
Vector2(float x, float y)
: x_(x), y_(y)
{
}
float x_;
float y_;
};
struct Texture
{
Texture(unsigned int width, unsigned int height)
: width_(width), height_(height)
{
bits_.insert(bits_.end(), width*height * 3, 0);
}
unsigned char* GetTexel(unsigned int x, unsigned int y)
{
return &bits_[((x * height_) + y)*3];
}
unsigned int width_;
unsigned int height_;
std::vector<unsigned char> bits_;
};
unsigned int CompileVertexShader(const std::string& sourceCode)
{
GLint result = GL_FALSE;
GLuint vertexShaderID = gl_->glCreateShader(GL_VERTEX_SHADER);
const char* src = sourceCode.c_str();
gl_->glShaderSource(vertexShaderID, 1, &src, NULL);
gl_->glCompileShader(vertexShaderID);
gl_->glGetShaderiv(vertexShaderID, GL_COMPILE_STATUS, &result);
if (result == GL_FALSE)
{
int infoLogLength;
gl_->glGetShaderiv(vertexShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
std::vector<GLchar> error(infoLogLength);
gl_->glGetShaderInfoLog(vertexShaderID, infoLogLength, &infoLogLength, &error[0]);
std::string errStr(&error[0], error.size());
OutputDebugString(errStr.c_str());
return 0;
}
return vertexShaderID;
}
unsigned int CompileFragmentShader(const std::string& sourceCode)
{
GLint result = GL_FALSE;
GLuint fragmentShaderID = gl_->glCreateShader(GL_FRAGMENT_SHADER);
const char* src = sourceCode.c_str();
gl_->glShaderSource(fragmentShaderID, 1, &src, NULL);
gl_->glCompileShader(fragmentShaderID);
gl_->glGetShaderiv(fragmentShaderID, GL_COMPILE_STATUS, &result);
if (result == GL_FALSE)
{
int infoLogLength;
gl_->glGetShaderiv(fragmentShaderID, GL_INFO_LOG_LENGTH, &infoLogLength);
std::vector<GLchar> error(infoLogLength);
gl_->glGetShaderInfoLog(fragmentShaderID, infoLogLength, &infoLogLength, &error[0]);
std::string errStr(&error[0], error.size());
OutputDebugString(errStr.c_str());
return 0;
}
return fragmentShaderID;
}
unsigned int LinkShaderProgram(unsigned int vertexShader, unsigned int fragmentShader)
{
// attempt to link the program...
GLint result = GL_FALSE;
unsigned int programID = gl_->glCreateProgram();
gl_->glAttachShader(programID, vertexShader);
gl_->glAttachShader(programID, fragmentShader);
gl_->glLinkProgram(programID);
gl_->glGetProgramiv(programID, GL_LINK_STATUS, &result);
if (result == GL_FALSE)
{
int InfoLogLength;
gl_->glGetProgramiv(programID, GL_INFO_LOG_LENGTH, &InfoLogLength);
std::vector<GLchar> error(InfoLogLength);
gl_->glGetProgramInfoLog(programID, InfoLogLength, &InfoLogLength, &error[0]);
std::string errStr(&error[0], error.size());
OutputDebugString(errStr.c_str());
return 0;
}
gl_->glDetachShader(programID, vertexShader);
gl_->glDetachShader(programID, fragmentShader);
return programID;
}
void SetUniform(const std::string& name, unsigned int ID)
{
int location = gl_->glGetUniformLocation(programID_, name.c_str());
if (location < 0)
OutputDebugString("Unable to find uniform location :(");
else
gl_->glUniform1i(location, ID);
}
std::shared_ptr<Texture> LoadTexture(const std::string& filename)
{
CImage image;
image.Load(filename.c_str());
std::shared_ptr<Texture> texture(new Texture(image.GetWidth(), image.GetHeight()));
for (int y = image.GetHeight() - 1; y >= 0; --y)
{
for (int x = 0; x < image.GetWidth(); ++x)
{
unsigned char* target = texture->GetTexel(x, y);
unsigned char* source = reinterpret_cast<unsigned char*>(image.GetPixelAddress(x, y));
for ( unsigned int c = 0; c < 3; ++c )
*(target+c) = *(source+c);
}
}
return texture;
}
}
extern "C" __declspec(dllexport) int OpenGLInit(void* hdc)
{
// We need to create a context or get an existing one that fits the supplied context.
// first check we have a valid device context
if (!hdc)
return 1;
HDC hDC = static_cast<HDC>(hdc);
if (!hDC)
return 2;
// we then need to get a valid DC...
PIXELFORMATDESCRIPTOR pfd;
memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));
pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR);
pfd.nVersion = 1;
pfd.dwFlags = PFD_DOUBLEBUFFER | PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW;
pfd.iPixelType = PFD_TYPE_RGBA;
pfd.cColorBits = 32;
pfd.cDepthBits = 32;
pfd.cStencilBits = 8;
pfd.iLayerType = PFD_MAIN_PLANE;
int nPixelFormat = ChoosePixelFormat(hDC, &pfd);
if (nPixelFormat == 0)
return 3;
if (!SetPixelFormat(hDC, nPixelFormat, &pfd))
return 4;
HGLRC tempContext = wglCreateContext(hDC);
wglMakeCurrent(hDC, tempContext);
int attribs[] =
{
WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
WGL_CONTEXT_MINOR_VERSION_ARB, 1,
WGL_CONTEXT_FLAGS_ARB, 0,
0
};
PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress("wglCreateContextAttribsARB");
if (wglCreateContextAttribsARB)
{
hglrc_ = wglCreateContextAttribsARB(hDC, 0, attribs);
wglMakeCurrent(NULL, NULL);
wglDeleteContext(tempContext);
if (!wglMakeCurrent(hDC, hglrc_))
return 5;
}
// Initialise the functions..
gl_ = new GLFunc();
// Cache the geometry for a quad
float v = 1.0f;
std::vector<Vector3> quadPoints = std::initializer_list<Vector3>({
Vector3(-v, -v, 0),
Vector3(v, -v, 0),
Vector3(v, v, 0),
Vector3(-v, v, 0)
});
std::vector<Vector2> quadUVs = std::initializer_list<Vector2>({
Vector2(0, 0),
Vector2(1.0f, 0),
Vector2(1.0f, 1.0f),
Vector2(0, 1.0f)
});
std::vector<unsigned int> quadIndexes = std::initializer_list<unsigned int>({
0, 1, 2, 2, 3, 0
});
gl_->glGenVertexArrays(1, &vao_);
gl_->glBindVertexArray(vao_);
// Cache the points...
gl_->glGenBuffers(1, &points_);
gl_->glBindBuffer(GL_ARRAY_BUFFER, points_);
gl_->glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * quadPoints.size(), &quadPoints[0].x_, GL_STATIC_DRAW);
gl_->glEnableVertexAttribArray(0);
gl_->glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
// Cache the UVs...
gl_->glGenBuffers(1, &uvs_);
gl_->glBindBuffer(GL_ARRAY_BUFFER, uvs_);
gl_->glBufferData(GL_ARRAY_BUFFER, sizeof(float) * quadUVs.size() * 2, &quadUVs[0].x_, GL_STATIC_DRAW);
gl_->glEnableVertexAttribArray(1);
gl_->glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);
// Cache the indexes...
gl_->glGenBuffers(1, &indexes_);
gl_->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexes_);
gl_->glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(unsigned int) * quadIndexes.size(), &quadIndexes[0], GL_STATIC_DRAW);
gl_->glBindBuffer(GL_ARRAY_BUFFER, NULL);
gl_->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, NULL);
gl_->glBindVertexArray(NULL);
// Load the texture...
std::shared_ptr<Texture> calibrationImage = LoadTexture("uvgrid.jpg");
glGenTextures(1, &calibrationTexture_);
glBindTexture(GL_TEXTURE_2D, calibrationTexture_);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, calibrationImage->width_, calibrationImage->height_, 0, GL_RGB, GL_UNSIGNED_BYTE, &calibrationImage->bits_[0]);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_2D, NULL);
// Compile the shaders
const char* fragmentSource = R"(
#version 410 core
uniform sampler2D quadTexture;
in vec2 UV;
out vec3 COLOUR;
void main()
{
//COLOUR = vec3(UV.st, 0);
COLOUR = texture(quadTexture, UV).bgr;
}
)";
const char* vertexSource = R"(
#version 410 core
in vec3 inP;
in vec2 inUV;
out vec2 UV;
void main()
{
gl_Position = vec4(inP, 1.0);
UV = inUV;
}
)";
vertexShader_ = CompileVertexShader(vertexSource);
fragmentShader_ = CompileFragmentShader(fragmentSource);
programID_ = LinkShaderProgram(vertexShader_, fragmentShader_);
return 0;
}
extern "C" __declspec(dllexport) void OpenGLKill()
{
wglDeleteContext(hglrc_);
}
extern "C" __declspec(dllexport) void OpenGLDraw(void* hdc, float rotation)
{
HDC validHDC = static_cast<HDC>(hdc);
glClearColor(0.2f, 0.2f, 0.2f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
gl_->glUseProgram(programID_);
gl_->glBindVertexArray(vao_);
gl_->glBindBuffer(GL_ARRAY_BUFFER, uvs_);
gl_->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexes_);
// Assign the texture...
gl_->glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, calibrationTexture_);
SetUniform("quadTexture", calibrationTexture_);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
gl_->glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, NULL);
gl_->glBindVertexArray(NULL);
gl_->glUseProgram(NULL);
SwapBuffers(validHDC);
}
extern "C" __declspec(dllexport) void OpenGLResize(int width, int height)
{
glViewport(0, 0, width, height);
//glMatrixMode(GL_PROJECTION);
//glLoadIdentity();
//glOrtho(width / static_cast<float>(height), -width / static_cast<float>(height), -1.0f, 1.0f, 0.1f, 100.0f);
}
完整代码包括WPF客户端:https://github.com/spiroyster/wpfogl(分支" gl4"。
正如先前所述,我必须在绑定draw例程期间绑定纹理之前明确调用 gl_->glActiveTexture(GL_TEXTURE1)
,即使我以前从未在此之前设置主动纹理单元(并且只有一个纹理加载在上下文中(。如果我删除该行,即主动纹理单元为GL_TEXTURE0
,则不会显示纹理。
这是我加载的所有后续纹理的遵循...即,如果我在此实例/上下文中加载的第二个纹理,则必须设置活动纹理单元以说GL_TEXTURE2
....即使我是仅使用上述纹理。即,即使我只使用第二个纹理进行抽奖(而不是第一个加载的纹理(,我仍然必须明确将活动纹理单元设置为GL_TEXTURE2
。
您必须将其设置为纹理采样器统一的值是纹理单元的索引,而不是纹理对象。
这样更改您的代码:
gl_->glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, calibrationTexture_);
// this is wrong
//SetUniform("quadTexture", calibrationTexture_);
SetUniform( "quadTexture", 1 ); // 1 because of GL_TEXTURE1
请参阅OpenGL 4.6 API兼容性配置文件规范;7.10个采样器;第154页:
采样器是开放式阴影语言中使用的特殊制服来识别 每个纹理查找使用的纹理对象。采样器的值表示要访问的纹理图像单元。将采样器的值设置为
i
选择纹理图像单位编号i
。
请注意,纹理对象的"名称"由
glGenTextures(1, &calibrationTexture_);
此"名称"(一个积分号(是硬件和驱动程序依赖性。
但是,由于您的代码中只有1个纹理对象,因此名称的值很可能为1。
这意味着,当您设置
时gl_->glActiveTexture(GL_TEXTURE1);
您的代码有效,因为calibrationTexture_
的值是1。
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