大佬教程收集整理的这篇文章主要介绍了c – 使用FreeType / GLFW完全不渲染文本,大佬教程大佬觉得挺不错的,现在分享给大家,也给大家做个参考。
Initializing FreeType version 2.4.10... opening font file FreeSans.ttf... Loading glyph set and shaders... Compiling shader textshader.vs... Compiling shader textshader.fs... Linking program... Drawing text... 16.666667 ms/frame
这是我的绘图功能
void text::draw(const char* text,float x,float y,float sx,float sy) { const char *p; FT_GlyphSlot g = face->glyph; GLuint tex; glActiveTexture(GL_TEXTURE0); glGentextures(1,&teX); glBindTexture(GL_TEXTURE_2D,teX); glUniform1i(uniform_tex,0); glPixelStorei(GL_UNPACK_ALIGNMENT,1); 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); glEnabLevertexAttribArray(attribute_coord); glBindBuffer(GL_ARRAY_BUFFER,vbo); glVertexAttribPointer(attribute_coord,4,GL_FLOAT,GL_falSE,0); for(p = text; *p; p++) { if(FT_Load_Char(face,*p,FT_LOAD_RENDER)) conTinue; glTexImage2D( GL_TEXTURE_2D,GL_ALPHA,g->bitmap.width,g->bitmap.rows,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},{x2 + w,1,{x2,-y2 - h,1},1} }; glBufferData(GL_ARRAY_BUFFER,sizeof Box,Box,GL_DYNAMIC_DRAW); glDrawArrays(GL_TRIANGLE_StriP,4); x += (g->advance.x >> 6) * sx; y += (g->advance.y >> 6) * sy; } glDisabLevertexAttribArray(attribute_coord); gldeleteTextures(1,&teX); }
这是我执行绘图功能的地方
void window::handleEventsAndRender() { if(!isOpen) { printf("Must open a window first to render and handle events!"); return; } float sx = 2/1024; float sy = 2/786; text test("FreeSans.ttf"); glUseProgram(test.textProgram); GLfloat black[4] = {0,1}; glUniform4fv(test.uniform_color,black); printf("Drawing text...\n"); while(glfwGetWindowParam(GLFW_OPENED)) { glClearColor(1,1); glClear(GL_COLOR_BUFFER_BIT); glDisable(GL_CULL_FACE); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA); test.draw("The Quick Brown Fox Jumps Over The Lazy Dog",-1 + 8 * sx,1 - 50 * sy,sx,sy); glfwSwapBuffers(); printFPS(); } glfwTerminate(); }
最后,这是我的着色器
顶点
#version 120 attribute vec4 coord; varying vec2 texpos; void main(void) { gl_Position = vec4(coord.xy,1); texpos = coord.zw; }
分段
#version 120 varying vec2 texpos; uniform sampler2d tex; uniform vec4 color; void main(void) { gl_FragColor = vec4(1,texture2D(tex,texpos).a) * color; }
有人可以帮帮我吗?
float sx = 2/1024; // sx == 0,2 is int and 1024 is int. 2 / 1024 -> sx == 0 // ... test.draw("The Quick Brown Fox Jumps Over The Lazy Dog",sy); // is actually calling like this test.draw("The Quick Brown Fox Jumps Over The Lazy Dog",-1,0); // then in text::draw float w = g->bitmap.width * sx; -> w == 0
修复sx和sy初始化:
float sx = float(2)/float(1024); // or float sx = 2.0f / 1024.0f;
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