[英]OepnGL sampling multitpe textures returns same texture color
main.cpp主程序
#define GLFW_INCLUDE_NONE
#include <GLFW/glfw3.h>
#include <glad/glad.h>
#include <fstream>
#include <iostream>
#include <string>
#include <stdio.h>
#include <SOIL/SOIL.h>
typedef struct vertex{
float x; float y; float z;
float texX; float texY;
float texIndex;
} vertex;
void readTextFile(const char* path, std::string* dst);
int main(){
std::cout << 3 << std::endl;
GLFWwindow* window;
if(!glfwInit())
return -1;
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
window = glfwCreateWindow(640, 480, "Geometry Shader Bathing with Texture Atlas", NULL, NULL);
if(!window){
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
gladLoadGL();
glfwSwapInterval(1);
glFrontFace(GL_CW);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
//create and set vertex buffer
vertex vertices[] = {
-1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
-1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
0.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.0f,
0.0f, -1.0f, 0.0f, 1.0f, 1.0f, 0.0f,
-1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f,
};
GLuint vertexBuffer;
glGenBuffers(1, &vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_DYNAMIC_DRAW);
//create vertex shader
std::string* shaderSource = new std::string();
readTextFile("shader/vertexShader.glsl", shaderSource);
const char* vertexShaderSourcePtr = shaderSource->c_str();
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSourcePtr, NULL);
glCompileShader(vertexShader);
GLint status;
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &status);
if(status == GL_FALSE){
char buffer[512];
glGetShaderInfoLog(vertexShader, 512, NULL, buffer);
std::cout << "vertexShader FAIL : " << std::endl <<
shaderSource <<std::endl
<< buffer << std::endl;
}else{
std::cout << "vertexShader compile success!" << std::endl;
}
//create fragment shader
readTextFile("shader/fragmentShader.glsl", shaderSource);
const char* fragmentShaderSourcePtr = shaderSource->c_str();
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSourcePtr, NULL);
glCompileShader(fragmentShader);
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &status);
if(status == GL_FALSE){
char buffer[512];
glGetShaderInfoLog(fragmentShader, 512, NULL, buffer);
std::cout << "fragmentShader FAIL : " << std::endl <<
shaderSource <<std::endl
<< buffer << std::endl;
}else{
std::cout << "fragmentShader compile success!" << std::endl;
}
delete shaderSource;
//create and set program
GLint program = glCreateProgram();
glAttachShader(program, vertexShader);
glAttachShader(program, fragmentShader);
glBindAttribLocation(program, 0, "inPos");
glBindAttribLocation(program, 1, "inTex");
glBindAttribLocation(program, 2, "inTexIndex");
glLinkProgram(program);
//set frameBuffer(renderTarget) index and fragmentShader output name
glBindFragDataLocation(program, 0, "outColor");
glUseProgram(program);
//create and set texture
int width = 384;
int height = 384;
unsigned char* textureRawData0 = SOIL_load_image("resource/character/test0.png", &width, &height, 0, SOIL_LOAD_RGBA);
unsigned char* textureRawData1 = SOIL_load_image("resource/character/test1.png", &width, &height, 0, SOIL_LOAD_RGBA);
glUniform1i(glGetUniformLocation(program, "texture0"), 0);
glUniform1i(glGetUniformLocation(program, "texture1"), 1);
GLuint texture1;
glGenTextures(1, &texture1);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureRawData0);
SOIL_free_image_data(textureRawData0);
std:: cout << "texture0: " << glGetUniformLocation(program, "texture0") << std::endl;
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
GLuint texture2;
glGenTextures(1, &texture2);
glActiveTexture(GL_TEXTURE0 + 1);
glBindTexture(GL_TEXTURE_2D, texture2);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureRawData1);
SOIL_free_image_data(textureRawData1);
std:: cout << "texture1: " << glGetUniformLocation(program, "texture1") << std::endl;
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//input layout : vertex Attribute
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glLinkProgram(program);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), 0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(vertex), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 1, GL_FLOAT, GL_FALSE, sizeof(vertex), (void*)(5 * sizeof(float)));
while(!glfwWindowShouldClose(window)){
int width, height;
glfwGetFramebufferSize(window, &width, &height);
glViewport(0, 0, width, height);
glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 12);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
void readTextFile(const char* path, std::string* dst){
std::ifstream f;
f.open(path);
if(f.is_open()){
std::string buff;
dst->clear();
while(!f.eof()){
std::getline(f, buff);
dst->append(buff);
dst->push_back('\n');
}
dst->push_back('\0');
f.close();
}else{
std::cout << "파일 열기 실패 : " << *dst << std::endl;
}
}
ps ps
#version 330 core
in vec2 outTex;
in float outTexIndex;
out vec4 outColor;
uniform sampler2D texture0;
uniform sampler2D texture1;
void main(){
if(outTexIndex == 0.0f){
outColor = texture(texture0, outTex);
}
else if(outTexIndex == 1.0f){
outColor = texture(texture1, outTex) + vec4(0.5f, 0.5f, 0.5f, 1.0f);
}
}
The input layout(vertex attribute) works fine.输入布局(顶点属性)工作正常。 TexIndex is transferred correctly. TexIndex 传输正确。 1.0f and 0.0f 1.0f 和 0.0f
But the problem is但问题是
//fragment shader //片段着色器
texture(texture0, outTex);
texture(texture1, outTex);
both returns same texture color but it is actually different texture from test1.png and test2.png.两者都返回相同的纹理颜色,但实际上与 test1.png 和 test2.png 的纹理不同。 what is the problem with my code?我的代码有什么问题?
++ I tried below fragment shader following the answer of @Rabbid76 ++我按照@Rabbid76的回答在片段着色器下面尝试过
#version 330 core
in vec2 outTex;
in float outTexIndex;
out vec4 outColor;
uniform sampler2D texture0;
uniform sampler2D texture1;
void main()
{
vec4 c1 = texture(texture0, outTex) + vec4(0.5f, 0.0f, 0.0f, 1.0f);
vec4 c2 = texture(texture1, outTex) + vec4(0.0f, 0.5f, 0.0f, 1.0f);
outColor = mix(c1, c2, outTexIndex);
}
Color applied but still sampling from same the texture.应用了颜色,但仍然从相同的纹理采样。 looks like somehow glActiveTexture(i);看起来有点像 glActiveTexture(i); doesn't work.不起作用。
ps.附: test1.png and test2.png is completely different picture. test1.png 和 test2.png 是完全不同的画面。 above screenshot is test1.png上面的截图是 test1.png
++ when I changed ++ 当我改变时
glGenTexture(1, &texture0);
glGenTexture(1, &texture1);
to到
glGenTexture(0, &texture0);
glGenTexture(0, &texture1);
then sampler2D texture0 and sampler2D texture1 both sample from texture1 test1.png (not form texture0 which is test0.png)然后sampler2D texture0和sampler2D texture1都从texture1 test1.png中采样(不是形成texture0,即test0.png)
what is happening?怎么了?
++ ++
vs对比
#version 330
in vec3 inPos;
in vec2 inTex;
in float inTexIndex;
out vec2 outTex;
out float outTexIndex;
void main(){
outTex = inTex;
gl_position = vec4(inPos, 1.0f);
outTexIndex = inTexIndex;
}
Since the condition if(outTexIndex == 0.0f)
depends on a fragment shader input, that may cause undefined behavior.由于条件if(outTexIndex == 0.0f)
取决于片段着色器输入,因此可能会导致未定义的行为。
See (most recent) OpenGL Shading Language 4.60 Specification - 8.9.请参阅(最新) OpenGL Shading Language 4.60 Specification - 8.9。 Texture Functions 纹理函数
[...] Some texture functions (non-“Lod” and non-“Grad” versions) may require implicit derivatives. [...] 一些纹理函数(非“Lod”和非“Grad”版本)可能需要隐式导数。 Implicit derivatives are undefined within non-uniform control flow and for non-fragment shader texture fetches.在非均匀控制流和非片段着色器纹理提取中,隐式导数未定义。 [...] [...]
respectively Non-uniform flow control .分别为非均匀流量控制。
Lookup both textures and mix
the colors to solve the issue:查找两个纹理并mix
颜色以解决问题:
#version 330 core
in vec2 outTex;
in float outTexIndex;
out vec4 outColor;
uniform sampler2D texture0;
uniform sampler2D texture1;
void main()
{
vec4 c1 = texture(texture0, outTex);
vec4 c2 = texture(texture1, outTex) + vec4(0.5f, 0.5f, 0.5f, 1.0f);
outColor = mix(c1, c2, outTexIndex);
}
I thought if I have a compiled example of multiple textures that working no problem, then I can find the problem of my code changing my code line to line comparing with the example.我想如果我有一个编译好的多个纹理的例子,它可以正常工作,那么我可以找到我的代码改变我的代码行与示例进行比较的问题。 So I found this one.所以我找到了这个。
It was SDL based.它是基于 SDL 的。 So I changed initialization code and loop to glfw.所以我将初始化代码和循环改为glfw。 And It worked fine on my environment.它在我的环境中运行良好。
Even after I changed my code's texture loading part completely same with the example, the problem wasn't solved.即使我更改了与示例完全相同的代码的纹理加载部分,问题也没有解决。 So it must be other part that makes the problem.所以一定是其他部分造成了问题。 Finally, I found this.最后,我找到了这个。
//input layout : vertex Attribute
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
//*****here!*****
//glLinkProgram(program);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(vertex), 0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(vertex), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(2);
glVertexAttribPointer(2, 1, GL_FLOAT, GL_FALSE, sizeof(vertex), (void*)(5 * sizeof(float)));
After I just add two characters "//", result was shown as I intended.在我添加两个字符“//”后,结果如我所愿。 I'm not sure about the reason that one line of code makes problem.我不确定一行代码出现问题的原因。
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