利用自定义顶点和片元着色器渲染，并且设置图片纹理颜色为画笔颜色
我要评论- (void)renderlinefrompoint:(cgpoint)start topoint:(cgpoint)end
{
//顶点缓存区
static glfloat *vertexbuffer = null;
//顶点max
static nsuinteger vertexmax = 64;
//顶点个数
nsuinteger vertexcount = 0,count;
cgfloat scale = self.contentscalefactor;
//点到像素转换：乘以比例因子
start.x *= scale;
start.y *= scale;
end.x *= scale;
end.y *= scale;
//开辟顶点缓存区
if (vertexbuffer == null) {
vertexbuffer = malloc(vertexmax*2*sizeof(glfloat));
}
//求得两点之间的距离
float seq = sqrtf((end.x-start.x)*(end.x-start.x)+(end.y-start.y)*(end.y-start.y));
/*向上取整：求得距离要产生多少个点
kbrushpixelstep值越大，笔触越细；值越小，笔触越粗
*/
nsinteger pointcount = ceil(seq/kbrushpixelstep);
count = max(pointcount, 1);
for (int i = 0; i < count; i++) {
if (vertexcount == vertexmax) {
//修改2倍增长
vertexmax = 2*vertexmax;
vertexbuffer = realloc(vertexbuffer, vertexmax*2*sizeof(glfloat));
}
//计算两个之间的距离有多少个点，并存储在顶点缓存区中
vertexbuffer[2*vertexcount+0] = start.x+(end.x-start.x)*((glfloat)i/(glfloat)count);
vertexbuffer[2*vertexcount+1] = start.y+(end.y-start.y)*((glfloat)i/(glfloat)count);
vertexcount++;
}
//绑定顶点数据
glbindbuffer(gl_array_buffer, vboid);
//将数据从cpu中复制到gpu中提供给opengl使用
glbufferdata(gl_array_buffer, vertexcount*2*sizeof(glfloat), vertexbuffer, gl_dynamic_draw);
//启用指定属性
glenablevertexattribarray(attrib_vertex);
//链接顶点属性
glvertexattribpointer(attrib_vertex, 2, gl_float, gl_false, 2*sizeof(glfloat), 0);
//使用数据总线：传递顶点数据到顶点着色器
gluseprogram(program[programe_point].id);
//绘制顶点：绘制模型、起始点、顶点个数
gldrawarrays(gl_points, 0, (int)vertexcount);
//绑定渲染缓存区到特定标志符上
glbindrenderbuffer(gl_renderbuffer, viewrenderbuffer);
//开始渲染
[context presentrenderbuffer:gl_renderbuffer];
}
- (textureinfo_t)texturefromname:(nsstring *)name
{
cgimageref brushimage;
cgcontextref brushcontext;
glubyte *brushdata;
size_t width, height;
gluint texid;
textureinfo_t texture;
brushimage = [uiimage imagenamed:name].cgimage;
width = cgimagegetwidth(brushimage);
height = cgimagegetheight(brushimage);
//开辟纹理图片内存
brushdata = (glubyte *)calloc(width*height*4, sizeof(glubyte));
/*创建位图上下文
参数：图片内存地址、图片宽、图片高、像素组件位数（一般设置8），每一行所占比特数、颜色空间、颜色通道
*/
brushcontext = cgbitmapcontextcreate(brushdata, width, height, 8, width*4, cgimagegetcolorspace(brushimage), kcgimagealphapremultipliedlast);
//绘图
cgcontextdrawimage(brushcontext, cgrectmake(0, 0, (cgfloat)width, (cgfloat)height), brushimage);
//释放上下文
cgcontextrelease(brushcontext);
//申请纹理标志符
glgentextures(1, &texid);
//绑定纹理
glbindtexture(gl_texture_2d, texid);
//设置纹理属性：缩小滤波器、线性滤波器
gltexparameteri(gl_texture_2d, gl_texture_min_filter, gl_linear);
/*生成2d纹理图片
参数：纹理目标、图像级别（0为基本级别）、颜色组件（gl_rgba、gl_alpha）、图像宽、图像高、边框宽度（一般为0）、像素数据颜色格式、像素数据类型、内存中指向图像数据指针
*/
glteximage2d(gl_texture_2d, 0, gl_rgba, (int)width, (int)height, 0, gl_rgba, gl_unsigned_byte, brushdata);
free(brushdata);
//配置纹理属性
texture.id = texid;
texture.width = (int)width;
texture.height = (int)height;
return texture;
}
- (void)setupshaders
{
for (int i = 0; i < num_programs; i++) {
//读取顶点着色器程序
char *vsrc = readfile(pathforresource(program[i].vert));
//读取片元着色器程序
char *fsrc = readfile(pathforresource(program[i].frag));
nsstring *vsrcstr = [[nsstring alloc] initwithbytes:vsrc length:strlen(vsrc)-1 encoding:nsutf8stringencoding];
nsstring *fsrcstr = [[nsstring alloc] initwithbytes:fsrc length:strlen(fsrc)-1 encoding:nsutf8stringencoding];
nslog(@"vsrcstr------%@", vsrcstr);
nslog(@"fsrcstr------%@", fsrcstr);
glsizei attribct = 0;
glchar *attribused[num_attribs];
glint attrib[num_attribs];
glchar *attribname[num_attribs] = {
"invertex"
};
const char *uniformname[num_uniforms] = {
"mvp","pointsize","vertexcolor", "texture"
};
for (int j = 0; j < num_attribs; j++) {
if (strstr(vsrc, attribname[j])) {
attrib[attribct] = j;
attribused[attribct++] = attribname[j];
}
}
//program处理：创建、链接、生成
gluecreateprogram(vsrc, fsrc, attribct, (const char **)&attribused[0], attrib, num_uniforms, &uniformname[0], program[i].uniform, &program[i].id);
free(vsrc);
free(fsrc);
if (i == programe_point) {
gluseprogram(program[programe_point].id);
//为当前程序指定uniform变量
gluniform1i(program[programe_point].uniform[uniform_texture], 0);
//设置正射投影矩阵
glkmatrix4 projectionmatrix = glkmatrix4makeortho(0, backingwidth, 0, backingheight, -1, 1);
//创建模型视图矩阵：单元矩阵
glkmatrix4 modelviewmatrix = glkmatrix4identity;
//正射投影矩阵与模型视图矩阵相乘，结果保存在mvpmatrix矩阵中
glkmatrix4 mvpmatrix = glkmatrix4multiply(projectionmatrix, modelviewmatrix);
/*为当前程序指定uniform变量值
参数：指明要更改的uniform变量的位置、将要被修改的矩阵的数量、矩阵值被载入变量时是否要对举证进行变换（如转置）、将要用于更新uniform变量mvp的数组指针
*/
gluniformmatrix4fv(program[programe_point].uniform[uniform_mvp], 1, gl_false, mvpmatrix.m);
//为当前程序对象uniform变量的pointsize赋值
gluniform1f(program[programe_point].uniform[uniform_point_size], brushtexture.width/kbrushscale);
//为当前程序对象uniform变量顶点颜色赋值
gluniform4fv(program[programe_point].uniform[uniform_vertex_color], 1, brushcolor);
}
}
glerror();
}
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