Transformations_练习二

尝试再次调用glDrawElements画出第二个箱子，只使用变换将其摆放在不同的位置。让这个箱子被摆放在窗口的左上角，并且会不断的缩放（而不是旋转）。（sin函数在这里会很有用，不过注意使用sin函数时应用负值会导致物体被翻转）

画图代码：

 1         //the first one
 2         // create transformations
 3         glm::mat4 transform = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
 4         transform = glm::translate(transform, glm::vec3(0.5f, -0.5f, 0.0f));
 5         transform = glm::rotate(transform, (float)glfwGetTime(), glm::vec3(0.0f, 0.0f, 1.0f));
 6 
 7         // get matrix's uniform location and set matrix
 8         ourShader.use();
 9         unsigned int transformLoc = glGetUniformLocation(ourShader.ID, "transform");
10         glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));
11 
12         // render container
13         glBindVertexArray(VAO);
14         glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
15 
16         //the second one
17         // create transformations
18         transform = glm::mat4(1.0f); // make sure to initialize matrix to identity matrix first
19         transform = glm::translate(transform, glm::vec3(-0.5f, 0.5f, 0.0f));
20         float scaleAmount = sin((float)glfwGetTime());
21         if (scaleAmount < 0)
22             transform = glm::scale(transform, glm::vec3(-scaleAmount, -scaleAmount, -scaleAmount));
23         else 
24             transform = glm::scale(transform, glm::vec3(scaleAmount, scaleAmount, scaleAmount));
25 
26         // get matrix's uniform location and set matrix
27         ourShader.use();
28         glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(transform));
29 
30         // render container
31         glBindVertexArray(VAO);
32         glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

View Code

2019/11/28