{

RenderHelp rh(600, 800);

// 加载模型

Model model("res/diablo3_pose.obj");

Vec3f eye_pos = {0, -0.5, 1.7};

Vec3f eye_at = {0, 0, 0};

Vec3f eye_up = {0, 1, 0};

Vec3f light_dir = {1, 1, 0.85}; // 光的方向

float perspective = 3.1415926f * 0.5f;

Mat4x4f mat_model = matrix_set_scale(1, 1, 1);

Mat4x4f mat_view = matrix_set_lookat(eye_pos, eye_at, eye_up);

Mat4x4f mat_proj = matrix_set_perspective(perspective, 6 / 8.0, 1.0, 500.0f);

Mat4x4f mat_mvp = mat_model * mat_view * mat_proj;

// 用于将法向量从模型坐标系变换到世界坐标系

Mat4x4f mat_model_it = matrix_invert(mat_model).Transpose();

// 顶点属性

struct { Vec3f pos; Vec3f normal; Vec2f uv; } vs_input[3];

const int VARYING_UV = 0;

const int VARYING_NORMAL = 1;

rh.SetVertexShader([&] (int index, ShaderContext& output) -> Vec4f {

Vec4f pos = vs_input[index].pos.xyz1() * mat_mvp;

Vec4f normal = (vs_input[index].normal.xyz1() * mat_model_it);

output.varying_vec2f[VARYING_UV] = vs_input[index].uv;

output.varying_vec3f[VARYING_NORMAL] = normal.xyz(); // 转化为三维

return pos;

});

rh.SetPixelShader([&] (ShaderContext& input) -> Vec4f {

Vec2f uv = input.varying_vec2f[VARYING_UV];

Vec3f n = input.varying_vec3f[VARYING_NORMAL];

Vec3f l = vector_normalize(light_dir);

Vec4f color = model.diffuse(uv); // 从模型取得纹理颜色

// 点乘 n,l 获得光照强度，Saturate 可以对范围 [0,1] 裁剪

float intense = Saturate(vector_dot(n, l)) + 0.1;

return color * intense;

});

// 迭代模型每一个面

for (int i = 0; i < model.nfaces(); i++) {

// 设置三个顶点的输入，供 VS 读取

for (int j = 0; j < 3; j++) {

vs_input[j].pos = model.vert(i, j);

vs_input[j].uv = model.uv(i, j);

vs_input[j].normal = model.normal(i, j);

}

// 绘制三角形

rh.DrawPrimitive();

}

rh.SaveFile("output.bmp");

#if defined(WIN32) || defined(_WIN32)

system("mspaint output.bmp");

#endif

return 0;