在我的应用程序中，我使用 OpenGL ES 渲染从 Internet 下载的文件，然后将其解析为顶点数组，因此我必须在启动后输入顶点和法线数据。我是 OpenGL ES 的新手，但我一直在阅读和学习。我已经设置了一个似乎工作正常的顶点和法线缓冲区，但我认为我将顶点和法线数据错误地放入缓冲区，因为当我加载视图时，那里有一个对象模糊地类似于我想要的形状但是三角形向各个方向偏离，形状的某些部分丢失了。这是我将数据输入缓冲区的代码：
for (int i = 0; i < triangle_cnt; i++) {
int base = i * 18;
GLfloat x1 = vertices[base];
GLfloat y1 = vertices[base + 1];
GLfloat z1 = vertices[base + 2];
GLfloat x2 = vertices[base + 6];
GLfloat y2 = vertices[base + 7];
GLfloat z2 = vertices[base + 8];
GLfloat x3 = vertices[base + 12];
GLfloat y3 = vertices[base + 13];
GLfloat z3 = vertices[base + 14];
vector_t normal;
vector_t U;
vector_t V;
GLfloat length;
U.x = x2 - x1;
U.y = y2 - y1;
U.z = z2 - z1;
V.x = x3 - x1;
V.y = y3 - y1;
V.z = z3 - z1;
normal.x = U.y * V.z - U.z * V.y;
normal.y = U.z * V.x - U.x * V.z;
normal.z = U.x * V.y - U.y * V.x;
length = normal.x * normal.x + normal.y * normal.y + normal.z * normal.z;
length = sqrt(length);
base = i * 9;
verticesBuff[base] = x1;
verticesBuff[base + 1] = y1;
verticesBuff[base + 2] = z1;
normalsBuff[base] = normal.x;
normalsBuff[base + 1] = normal.y;
normalsBuff[base + 2] = normal.z;
verticesBuff[base + 3] = x2;
verticesBuff[base + 4] = y2;
verticesBuff[base + 5] = z2;
normalsBuff[base + 3] = normal.x;
normalsBuff[base + 4] = normal.y;
normalsBuff[base + 5] = normal.z;
verticesBuff[base + 6] = x3;
verticesBuff[base + 7] = y3;
verticesBuff[base + 8] = z3;
normalsBuff[base + 6] = normal.x;
normalsBuff[base + 7] = normal.y;
normalsBuff[base + 8] = normal.z;
fprintf(stderr, "%ff, %ff, %ff, %ff, %ff, %ff, \n", x1, y1, z1, normal.x, normal.y, normal.z);
fprintf(stderr, "%ff, %ff, %ff, %ff, %ff, %ff, \n", x2, y2, z2, normal.x, normal.y, normal.z);
fprintf(stderr, "%ff, %ff, %ff, %ff, %ff, %ff, \n", x3, y3, z3, normal.x, normal.y, normal.z);
}
这是我用于使用这些缓冲区的代码：
- (void)setupGL {
[EAGLContext setCurrentContext:self.context];
[self loadShaders];
self.effect = [[GLKBaseEffect alloc] init];
self.effect.light0.enabled = GL_TRUE;
self.effect.light0.diffuseColor = GLKVector4Make(.05f, .55f, 1.0f, 1.0f);
glEnable(GL_DEPTH_TEST);
glGenVertexArraysOES(1, &_vertexArray);
glBindVertexArrayOES(_vertexArray);
glGenBuffers(1, &_vertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, _vertexBuffer);
glBufferData(GL_ARRAY_BUFFER, vertCount*sizeof(verticesBuff)*3*2, NULL, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(verticesBuff) * vertCount * 3, verticesBuff);
glBufferData(GL_ARRAY_BUFFER, vertCount*sizeof(normalsBuff)*3*2, NULL, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, sizeof(GLfloat) * vertCount * 3, sizeof(normalsBuff) * vertCount * 3, normalsBuff);
glEnableVertexAttribArray(GLKVertexAttribPosition);
glVertexAttribPointer(GLKVertexAttribPosition, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(0));
glEnableVertexAttribArray(GLKVertexAttribNormal);
glVertexAttribPointer(GLKVertexAttribNormal, 3, GL_FLOAT, GL_FALSE, 24, BUFFER_OFFSET(12));
glBindVertexArrayOES(0);
_rotMatrix = GLKMatrix4Identity;
_quat = GLKQuaternionMake(0, 0, 0, 1);
_quatStart = GLKQuaternionMake(0, 0, 0, 1);
}
- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {
glClearColor(0.78f, 0.78f, 0.78f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindVertexArrayOES(_vertexArray);
// Render the object with GLKit
[self.effect prepareToDraw];
glVertexPointer(3, GL_FLOAT, 0, verticesBuff);
glNormalPointer(GL_FLOAT, 0, normalsBuff);
glDrawArrays(GL_TRIANGLES, 0, vertCount); //*******************************
// Render the object again with ES2
glUseProgram(_program);
glUniformMatrix4fv(uniforms[UNIFORM_MODELVIEWPROJECTION_MATRIX], 1, 0, _modelViewProjectionMatrix.m);
glUniformMatrix3fv(uniforms[UNIFORM_NORMAL_MATRIX], 1, 0, _normalMatrix.m);
glDrawArrays(GL_TRIANGLES, 0, vertCount);
}
如果我在创建 OpenGL ES 应用程序时使用 Apple 提供的代码获取这些日志并将它们粘贴到示例应用程序的顶点数组中，那么对象会呈现得很漂亮，所以我推断我一定只是将顶点数据放错了。
那么有人可以帮助我理解输入顶点和法线时我做错了什么吗？任何帮助表示赞赏。
这也是我的渲染的样子：
至少在形状上，它应该是这样的：
