2D opengl旋转会导致精灵变形 [英] 2D opengl rotation causes sprite distortion

问题描述

我对使用OpenGL ES 2.0非常陌生.我也使用iPhone和GLM数学库.正如我所引用的，我经常使用本教程: http: //tomdalling.com/blog/modern-opengl/03-matrices-depth-buffering-animation/但我发现很难找到2D OpenGL教程.

I am quite new to using OpenGL ES 2.0. Also im using an iPhone and the GLM maths library. As I reference I have been using this tutorial a lot: http://tomdalling.com/blog/modern-opengl/03-matrices-depth-buffering-animation/ But I have found it difficult to find a 2D OpenGL tutorial.

我正在尝试旋转2D精灵，但是图像失真了. 例如，旋转角度为0度: http://i.imgur.com/yBTN2ST.png并以45度的旋转角度: http://i.imgur.com/cY5IJcg.png

I am trying to rotate a 2D sprite but the image is being distorted. For example at a rotation angle of 0 degrees: http://i.imgur.com/yBTN2ST.png and at a rotation angle of 45 degrees: http://i.imgur.com/cY5IJcg.png

在我的Sprite班中

glm::mat4 projection = glm::ortho(0.0f, 480.0f, 0.0f, 320.0f);
glUniformMatrix4fv(projectionUniform, 1, GL_FALSE, glm::value_ptr(projection));

glm::mat4 newModel = glm::rotate(glm::mat4(), 0.0f, glm::vec3(0, 0, 1));
glUniformMatrix4fv(modelUniform, 1, GL_FALSE, value_ptr(newModel));

glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

在我的顶点着色器中

vec4 newPosition = vec4(position + offset, 0.0, 1.0);
gl_Position = model * projection * newPosition;

我认为部分问题是图像旋转时没有考虑长宽比，我不确定该如何解决.

I think that part of the problem is that the image is being rotated without considering the aspect ratio im not really sure how to fix this.

谢谢

推荐答案

我认为您以错误的顺序应用了转换.

I think you are applying your transformations in the wrong order.

代替:

gl_Position = model * projection * newPosition;

尝试:

gl_Position = projection * model * newPosition;

更好(避免将两个4x4矩阵相乘):

Better still (to avoid multiplying two 4x4 matrices together):

gl_Position = projection * ( model * newPosition );

甚至更好:在您的应用程序中将矩阵相乘，并在着色器中进行一次矩阵矢量相乘.您可能还应该在矩阵中包含翻译.

Even better: Multiply your matrices in your application and do a single matrix-vector multiplication in your shader. You should probably also include the translation in the matrix.

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