【学习日志】2022.09.15 game-physics-cookbook---Point Test ​OpenGL - Drawing polygons​_gamephysicscookbook

vdoc.pub_game-physics-cookbook 

 

 

 

 

 

 

 

 

主要用到这个：Point and plane 

 

 

 

 

 

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 ZENO代码改进

 

把向量proj拆成a+b再算uv时  发现向量b*uv可以消掉,n便多余了，故可以改成：

#include <zeno/zeno.h>
#include <zeno/types/PrimitiveObject.h>
#include <zeno/types/NumericObject.h>
#include <stdexcept>
#include "zeno/utils/log.h"
#define CMP(x, y) \
	(fabsf(x - y) <= FLT_EPSILON * fmaxf(1.0f, fmaxf(fabsf(x), fabsf(y))))
 
namespace zeno {
struct UVProjectFromPlane : zeno::INode {
    virtual void apply() override {
        auto prim = get_input<PrimitiveObject>("prim");
        auto &uv = prim->verts.add_attr<vec3f>("uv");
        auto refPlane = get_input<PrimitiveObject>("refPlane");
 
//        bool PointOnPlane(const Point& point, const Plane& plane) {
//            // This should probably use an epsilon!
//            //return Dot(point, plane.normal) - plane.distance == 0.0f;
//            return CMP(Dot(point, plane.normal) - plane.distance, 0.0f);
//        }
 
        if (refPlane->verts.size() != 4) {
            zeno::log_error("refPlane must be 1 * 1 plane!");
            throw zeno::makeError("refPlane must be 1 * 1 plane!");
        }
        auto originPos = refPlane->verts[2];
        auto xOffset = refPlane->verts[0];
        auto yOffset = refPlane->verts[3];
//        zeno::log_info("xOffset:{}, originPos: {}", xOffset, originPos);
        auto uDir = zeno::normalize(xOffset - originPos);
        auto vDir = zeno::normalize(yOffset - originPos);
        auto uLength = zeno::length(xOffset - originPos);
        auto vLength = zeno::length(yOffset - originPos);
//        auto n = zeno::cross(uDir, vDir);
//        zeno::log_info("uDir:{], uLength: {}, n: {}", uDir, uLength, n);
        for (auto i = 0; i < prim->size(); i++) {
            auto &vert = prim->verts[i];
            auto offset = vert - originPos;
            auto proj = offset;
            auto u = zeno::clamp(zeno::dot(proj, uDir) / uLength, 0, 1);
            auto v = zeno::clamp(zeno::dot(proj, vDir) / vLength, 0, 1);
            uv[i] = zeno::vec3f(u,  v, 0);
        }
        set_output("outPrim", std::move(prim));
    }
};
 
ZENDEFNODE(UVProjectFromPlane, {
    {
        {"PrimitiveObject", "prim"},
        {"PrimitiveObject", "refPlane"},
    },
    {
        {"PrimitiveObject", "outPrim"}
    },
    {},
    {"primitive"},
});
}

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opengl知识点

 

 

最后的初始化和绘制代码现在看起来像这样： 

// ..:: 初始化代码 :: ..
// 1. 绑定顶点数组对象
glBindVertexArray(VAO);
// 2. 把我们的顶点数组复制到一个顶点缓冲中，供OpenGL使用
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
// 3. 复制我们的索引数组到一个索引缓冲中，供OpenGL使用
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// 4. 设定顶点属性指针
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
 
[...]
 
// ..:: 绘制代码（渲染循环中） :: ..
glUseProgram(shaderProgram);
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0);

 OpenGL - Drawing polygons