[英]No texture if multiple textures in modern opengl
我正在使用帶有SDL2和glew的C ++和OpenGL 4.6。 我有一堂課Texture:
#include "stb_image/stb_image.h"
class Texture {
private:
unsigned int m_RendererID;
std::string m_FilePath;
unsigned char *m_LocalBuffer;
int m_Width, m_Height, m_BPP;
public:
Texture(const std::string &path);
~Texture();
void Bind(unsigned int slot = 0) const;
void Unbind() const;
inline int GetWidth() const { return m_Width; }
inline int GetHeight() const { return m_Height; }
inline int GetID() const { return m_RendererID; }
};
Texture::Texture(const std::string &path)
: m_RendererID(0), m_FilePath(path), m_LocalBuffer(nullptr), m_Width(0), m_Height(0), m_BPP(0)
{
stbi_set_flip_vertically_on_load(1); //Flip vertically because OpenGL renders texture in the opposite way
m_LocalBuffer = stbi_load(path.c_str(), &m_Width, &m_Height, &m_BPP, 4);
GLCall(glGenTextures(1, &m_RendererID));
GLCall(glBindTexture(GL_TEXTURE_2D, m_RendererID));
GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR));
GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR));
GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE));
GLCall(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP));
GLCall(glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, m_Width, m_Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, m_LocalBuffer));
GLCall(glBindTexture(GL_TEXTURE_2D, 0));
if (m_LocalBuffer) {
stbi_image_free(m_LocalBuffer);
}
}
Texture::~Texture() {
GLCall(glDeleteTextures(1, &m_RendererID));
}
void Texture::Bind(unsigned int slot) const {
GLCall(glActiveTexture(GL_TEXTURE0 + slot));
GLCall(glBindTexture(GL_TEXTURE_2D, m_RendererID));
}
void Texture::Unbind() const {
GLCall(glBindTexture(GL_TEXTURE_2D, 0));
}
如果創建一個紋理,該紋理將顯示:
Texture texture("ship.png");
texture.Bind(0);
shader.Bind();
va.Bind();
ib.Bind();
shader.SetUniform1i("u_Texture", 0);
glDrawElements(GL_TRIANGLES, ib.GetCount(), GL_UNSIGNED_INT, nullptr);
但是,如果我創建兩個紋理,我只會得到黑屏:
Texture texture("ship.png");
texture.Bind(0);
Texture texture2("ship2.png");
texture2.Bind(1);
shader.Bind();
va.Bind();
ib.Bind();
shader.SetUniform1i("u_Texture", 0);
glDrawElements(GL_TRIANGLES, ib.GetCount(), GL_UNSIGNED_INT, nullptr);
這應該工作。 我在互聯網上搜索了2個小時,但似乎找不到為什么無法正常工作的原因。 你們能幫我嗎?
在以下代碼行的末尾
Texture texture("ship.png"); texture.Bind(0); Texture texture2("ship2.png"); texture2.Bind(1);
第二個紋理對象( “ ship2.png” )綁定到紋理單元1,但是默認紋理對象(0)綁定到紋理單元0。
注意當Texture texture("ship.png");
被調用,然后創建紋理對象並將其綁定到當前紋理單元,然后將默認紋理對象(0)綁定到當前紋理單元:
Texture::Texture(const std::string &path) { GLCall(glBindTexture(GL_TEXTURE_2D, m_RendererID)); // [...] GLCall(glBindTexture(GL_TEXTURE_2D, 0)); }
請注意,您所謂的“ unbind”不會解除任何綁定。 glBindTexture(GL_TEXTURE_2D, 0)
將默認紋理對象( glBindTexture(GL_TEXTURE_2D, 0)
綁定到當前處於活動狀態的紋理單元。 沒有必要這樣做。
只需更改說明的順序即可解決您的問題。 首先創建並加載紋理對象。 然后將紋理對象綁定到紋理單元:
Texture texture("ship.png");
Texture texture2("ship2.png");
texture.Bind(0);
texture2.Bind(1);
shader.Bind();
va.Bind();
ib.Bind();
shader.SetUniform1i("u_Texture", 0);
glDrawElements(GL_TRIANGLES, ib.GetCount(), GL_UNSIGNED_INT, nullptr);
或者,可以避免使用紋理單位0。僅將紋理單位0用於創建紋理對象:
Texture::Texture(const std::string &path, unsigned int slot) {
GLCall(glActiveTexture(GL_TEXTURE0));
// [...]
}
Texture texture("ship.png");
texture.Bind(1); // <--- 1
Texture texture2("ship2.png");
texture2.Bind(2); // <--- 2
shader.Bind();
va.Bind();
ib.Bind();
shader.SetUniform1i("u_Texture", 1); // <--- 1
glDrawElements(GL_TRIANGLES, ib.GetCount(), GL_UNSIGNED_INT, nullptr);
或者將紋理單元的參數添加到Texture
類的構造函數中:
Texture::Texture(const std::string &path, unsigned int slot) {
GLCall(glGenTextures(1, &m_RendererID));
GLCall(glActiveTexture(GL_TEXTURE0 + slot));
GLCall(glBindTexture(GL_TEXTURE_2D, m_RendererID));
// [...]
// GLCall(glBindTexture(GL_TEXTURE_2D, 0)); <--- delete
}
Texture texture("ship.png", 0);
Texture texture2("ship2.png", 1);
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