[英]Can't get FreeType to render
嘗試使用OpenGL,GLM,GLAD,GLFW和FreeType嘗試獲取要渲染的字體。 我已逐步確保在渲染時沒有發生OpenGL錯誤,沒有內容發布錯誤代碼,但沒有內容呈現到屏幕上。 我也不確定我是否正確使用了glm的正交函數,因為我不確定在哪里實際使用該變量:
glm::mat4 projection = glm::ortho(0.0f, 800.0f, 0.0f, 600.0f);
這是我的Draw Loop,在場景初始化后調用它:
void GameLoop::Run()
{
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
while (!glfwWindowShouldClose(m_game_window))
{
// Do That thing where you draw everything
}
}
Font構造函數將字體加載到紋理中:
Salem::Graphics::Font::Font(std::string p_font_path)
{
FT_Library ft;
if (FT_Init_FreeType(&ft))
{
std::cout << "Error loading FreeType library" << std::endl;
}
FT_Face face;
if (FT_New_Face(ft, p_font_path.c_str(), 0, &face))
{
std::cout << "Error loading font;\n" << p_font_path << std::endl;
}
FT_Set_Pixel_Sizes(face, 0, 28);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1); // Disable byte-alignment restriction
for (GLubyte c = 0; c < 128; c++)
{
if (FT_Load_Char(face, c, FT_LOAD_RENDER))
{
std::cout << "Failed to load a character glyph." << std::endl;
continue;
}
GLuint texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(
GL_TEXTURE_2D,
0,
GL_RED,
face->glyph->bitmap.width,
face->glyph->bitmap.rows,
0,
GL_RED,
GL_UNSIGNED_BYTE,
face->glyph->bitmap.buffer);
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);
Character character = {
texture,
glm::ivec2(face->glyph->bitmap.width, face->glyph->bitmap.rows),
glm::ivec2(face->glyph->bitmap_left, face->glyph->bitmap_top),
face->glyph->advance.x
};
m_characters.insert(std::make_pair(c, character));
}
FT_Done_Face(face);
FT_Done_FreeType(ft);
std::cout << "Font loaded. " << std::endl;
}
我的文字的初始化功能:
void Text::Initialize()
{
glm::mat4 projection = glm::ortho(0.0f, 800.0f, 0.0f, 600.0f);
glGenVertexArrays(1, &m_vao);
glGenBuffers(1, &m_vbo);
glBindVertexArray(m_vao);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * 6 * 4, nullptr, m_draw_method);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(GLfloat), nullptr);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
而我的文字的繪制功能:
void Text::Draw()
{
glm::mat4 projection = glm::ortho(0.0f, 800.0f, 0.0f, 600.0f);
shader()->Use();
glUniform3f(glGetUniformLocation(shader()->id(), "textColor"), m_color.x, m_color.y, m_color.z);
glActiveTexture(GL_TEXTURE0);
glBindVertexArray(m_vao);
for (std::string::const_iterator c = m_text.begin(); c != m_text.end(); ++c)
{
Character ch = m_font.characters()[*c];
GLfloat xPosition = m_position.x + ch.Bearing.x * m_scale;
GLfloat yPosition = m_position.y - (ch.Size.y - ch.Bearing.y) * m_scale;
GLfloat width = ch.Size.x * m_scale;
GLfloat height = ch.Size.y * m_scale;
GLfloat vertices[6][4] = {
{xPosition, yPosition + height, 0.0, 0.0},
{xPosition, yPosition, 0.0, 1.0},
{xPosition + width, yPosition, 1.0, 1.0},
{xPosition, yPosition + height, 0.0, 0.0},
{xPosition + width, yPosition, 1.0, 1.0},
{xPosition + width, yPosition + height, 1.0, 0.0}
};
glBindTexture(GL_TEXTURE_2D, ch.TextureID);
glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
//glBindBuffer(GL_ARRAY_BUFFER, 0);
glDrawArrays(GL_TRIANGLES, 0, 6);
m_position.x += (ch.Advance >> 6) * m_scale;
}
glBindVertexArray(0);
glBindTexture(GL_TEXTURE_2D, 0);
}
不想讓帖子過長,如果需要我的着色器,請告訴我。
分解代碼后,我發現了一個有用的資源,這使我陷入了困境。 從https://learnopengl.com/#!In-Practice/Text-Rendering Project來源中,我發現在構造字體時必須將正交投影變量傳遞給我的着色器程序。 我是通過將以下代碼添加到我的字體構造函數中來實現的:
glm::mat4 projection = glm::ortho(0.0f, 800.0f, 0.0f, 600.0f);
p_shader->Use();
glUniformMatrix4fv(glGetUniformLocation(p_shader->id(), "projection"), 1, GL_FALSE, glm::value_ptr(projection));
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