[SOLVED] CS GPU // font.cpp

// font.cpp
//
// From https://en.wikibooks.org/wiki/OpenGL_Programming/Modern_OpenGL_Tutorial_Text_Rendering_01
//
// You must install FreeType: https://www.freetype.org/download.html
//
// The should be on your include path

#ifndef HAVE_FREETYPE

#include headers.h
void initFont( char *ttf_file, int height_in_pixels ) {}
void render_text( const char *text, int pixOriginX, int pixOriginY, GLFWwindow* window ) {}

#else

#include headers.h
#include gpuProgram.h
#include

#include // requires the freetype library.On Linux: sudo apt-get install libfreetype6-dev
#include FT_FREETYPE_H

static FT_Library ft;
static FT_Face face;
static GLuint vao, vbo, tex;
static GPUProgram *gpu;

char *vertexShader =

#version 300 es

layout (location = 0) in vec4 coord;

smooth out mediump vec2 texcoord;

void main(void) {

gl_Position = vec4(coord.xy, 0, 1);

texcoord = coord.zw;

};

char *fragmentShader =

#version 300 es

uniform sampler2D tex;

uniform mediump vec4 colour;

smooth in mediump vec2 texcoord;

out mediump vec4 fragColour;

void main(void) {

mediump float t = texture(tex, texcoord).r;

fragColour = vec4(1,1,1,t) * colour ;

};

void initFont( char *ttf_file, int height_in_pixels )

{
if(FT_Init_FreeType(&ft)) {
fprintf(stderr, Could not init freetype library
);
exit(1);
}

if(FT_New_Face(ft, ttf_file, 0, &face)) {
fprintf(stderr, Could not open font
);
exit(1);
}

FT_Set_Pixel_Sizes(face, 0, height_in_pixels);

glGenTextures( 1, &tex );
glGenVertexArrays( 1, &vao );
glGenBuffers( 1, &vbo );

gpu = new GPUProgram();
gpu->init( vertexShader, fragmentShader );
}

// Print a string at (x,y) on the display
//
// x,y is the start position in [-1,1]x[-1,1]
// sx,sy are the dimensions of a pixel in the [-1,1]x[-1,1] window coordinate system

void render_text( const char *text, int pixOriginX, int pixOriginY, GLFWwindow* window )

{
// Get size of a pixel in world coordinates [-1,1]x[-1,1]

int width, height;
glfwGetFramebufferSize( window, &width, &height );

float sx = 2.0 / (float) width;
float sy = 2.0 / (float) height;

// Postion the first character in world coordinates

float x = -1 + pixOriginX * sx;
float y = -1 + pixOriginY * sy;

// Code common to all character textures

if (tex != 1)
cout << “Font using texture ” << tex << endl;glActiveTexture( GL_TEXTURE1 );glBindTexture( GL_TEXTURE_2D, tex );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_NEAREST );glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );// GPU initgpu->activate();
gpu->setInt( tex, 1 ); // texture is managed by texture unit 1 (= GL_TEXTURE1 above)
gpu->setVec4( colour, vec4(0,0,0,1) ); // character colour

// Code common to all VBO init

glBindVertexArray( vao );
glBindBuffer( GL_ARRAY_BUFFER, vbo );

glVertexAttribPointer( 0, 4, GL_FLOAT, GL_FALSE, 0, 0 );
glEnableVertexAttribArray( 0 );

// Each character is drawn with one texture that provides the opacity

glEnable( GL_BLEND );
glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );

FT_GlyphSlot g = face->glyph;

for (const char *p=text; *p != ; p++) {

if ( FT_Load_Char(face, *p, FT_LOAD_RENDER) )
continue; // no texture available for this character

glTexImage2D( GL_TEXTURE_2D, 0, GL_RED, g->bitmap.width, g->bitmap.rows, 0, GL_RED, GL_UNSIGNED_BYTE, g->bitmap.buffer );

float x2 = x + g->bitmap_left * sx;
float y2 = -y g->bitmap_top * sy;
float w = g->bitmap.width * sx;
float h = g->bitmap.rows * sy;

GLfloat box[4][4] = {
{x2, -y2, 0, 0},
{x2 + w, -y2, 1, 0},
{x2, -y2 h, 0, 1},
{x2 + w, -y2 h, 1, 1},
};

glBufferData( GL_ARRAY_BUFFER, sizeof box, box, GL_DYNAMIC_DRAW );

glDrawArrays( GL_TRIANGLE_STRIP, 0, 4 );

x += (g->advance.x/64) * sx;
y += (g->advance.y/64) * sy;
}

// Disable everything

glDisable( GL_BLEND );
glDisableVertexAttribArray( 0 );
glBindBuffer( GL_ARRAY_BUFFER, 0 );
gpu->deactivate();

glBindVertexArray( 0 );
}

#endif