Freetype2 - glyphs not rendering/displaying - c++

Question

I am working on a 2D game engine and I want to implement text rendering. I want to use freetype. I have the following code:
GLuint va;
glGenVertexArrays(1, &va);
GLuint vb;
glGenBuffers(1, &vb);
glBindVertexArray(va);
glBindBuffer(GL_ARRAY_BUFFER, vb);
glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
FT_Face testface;
FT_Error error;
error = FT_New_Face(ftlib, "arial.ttf", 0, &testface);
if (error == FT_Err_Unknown_File_Format)
{
std::cout << "Font format not supported" << std::endl;
}
else if (error)
{
std::cout << "Something else" << "\n";
}
error = FT_Set_Pixel_Sizes(testface, 0, 48);
if (error)
{
std::cout << "Problem with set px szes occ\n";
}
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
for (unsigned char c = 0; c < 128; c++)
{
if (FT_Load_Char(testface, c, FT_LOAD_RENDER))
{
std::cout << "Error. Failed to load glyph "<<c<<"\n";
continue;
}
GLuint texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(
GL_TEXTURE_2D,
0,
GL_RED,
testface->glyph->bitmap.width,
testface->glyph->bitmap.rows,
0,
GL_RED,
GL_UNSIGNED_BYTE,
testface->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 newchar = {
texture,
glm::ivec2(testface->glyph->bitmap.width, testface->glyph->bitmap.rows),
glm::ivec2(testface->glyph->bitmap_left, testface->glyph->bitmap_top),
testface->glyph->advance.x
};
characters.insert(std::pair<char, Character>{c, newchar});
}
FT_Done_Face(testface);
//glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
glUseProgram(text_shader_program);
glUniform4f(glGetUniformLocation(text_shader_program, "textColor"), 1.f, 1.f, 1.f, 1.f);
glActiveTexture(GL_TEXTURE0);
std::string::const_iterator c;
std::string text = "TEST";
glBindVertexArray(va);
float x = 0.f;
for (c = text.begin(); c != text.end(); c++)
{
Character ch = characters[*c];
float xpos = x + ch.bearing.x;
float ypos = 0.f - (ch.size.y - ch.bearing.y);
float w = ch.size.x;
float h = ch.size.y;
float vertices[6][4] = {
{xpos, ypos + h, 0.f, 0.f},
{xpos, ypos, 0.f, 1.f},
{xpos + w, ypos, 1.f, 1.f},
{xpos, ypos + h, 0.f, 0.f},
{xpos + w, ypos, 1.f, 1.f},
{xpos + w, ypos + h, 1.f, 0.f}
};
glBindTexture(GL_TEXTURE_2D, ch.textureID);
glBindBuffer(GL_ARRAY_BUFFER, vb);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glDrawArrays(GL_TRIANGLES, 0, 6);
x += (ch.advance >> 6);
}
glBindVertexArray(0);
glBindTexture(GL_TEXTURE_2D, 0);
I initialize the library (before the above code happens) with
FT_Error error = FT_Init_FreeType(&ftlib);
if (error)
{
std::cout << "????" << std::endl;
}
The face and library initializes properly, glyphs are loaded, but nothing is drawn. I don't use camera, so all the coordinates are in space -1 to 1 if that matters.
I have the following shaders for text rendering:
vertexshader
#version 330 core
layout(location=0) in vec4 vertex;
out vec2 TextCoords;
void main() {
gl_Position = vec4(vertex.xy, 0.0, 1.0);
TextCoords = vertex.zw;
}
fragmentshader
#version 330 core
in vec3 TextCoords;
out vec4 color;
uniform sampler2D text;
uniform vec4 textColor;
void main(){
vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, TextCoords).r);
color = textColor * sampled;
}
Update:
I changed the line FT_Set_Pixel_Sizes(testface, 0, 48) to FT_Set_Pixel_Sizes(testface, 0, 1) and I got a huge gray rectangle where the text should be.
Has anyone got any ideas?

Answer 1

The problem seems to be the result of not using z-coordinate. The problem is, when using coordinate space -1 to 1, the text is rendering in too big scale to be seen or recognized. The solution is to use the z-coordinate as a static camera view, so for 500x500 window the borders are -250.f and 250.f