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    <p>You have to compute the matrix manually and then pass it to OpenGL.</p> <h2>Computing the matrix</h2> <p>This snippet of code is based on the <a href="https://www.khronos.org/registry/OpenGL-Refpages/gl2.1/xhtml/gluPerspective.xml" rel="nofollow noreferrer">gluPerspective documentation</a>.</p> <pre><code> void BuildPerspProjMat(float *m, float fov, float aspect, float znear, float zfar) { float f = 1/tan(fov * PI_OVER_360); m[0] = f/aspect; m[1] = 0; m[2] = 0; m[3] = 0; m[4] = 0; m[5] = f; m[6] = 0; m[7] = 0; m[8] = 0; m[9] = 0; m[10] = (zfar + znear) / (znear - zfar); m[11] = -1; m[12] = 0; m[13] = 0; m[14] = 2*zfar*znear / (znear - zfar); m[15] = 0; } </code></pre> <p>There is a C++ library called <a href="http://glm.g-truc.net/" rel="nofollow noreferrer">OpenGL Mathematics</a> that may be useful.</p> <h2>Loading the Matrix in OpenGL 3.1</h2> <p>I am still new to the OpenGL 3.1 API, but you need to update a matrix on the GPU and then make use of it in your vertex shader to get the proper perspective. The following code just loads the matrix using <a href="http://www.opengl.org/sdk/docs/man/xhtml/glUniform.xml" rel="nofollow noreferrer">glUniform4fv</a> onto the video card.</p> <pre><code>{ glUseProgram(shaderId); glUniformMatrix4fv(glGetUniformLocation(shaderId, "u_proj_matrix"), 1, GL_FALSE, theProjectionMatrix); RenderObject(); glUseProgram(0); } </code></pre> <p>A simple vertex shader from a random <a href="http://blog.mgrundmann.com/?p=4" rel="nofollow noreferrer">blog</a> (found through stack overflow).</p> <pre><code>attribute vec4 a_position; attribute vec4 a_color; varying vec4 v_color; uniform mat4 u_proj_matrix; uniform mat4 u_model_matrix; void main() { mat4 mvp_matrix = u_proj_matrix * u_model_matrix; v_color = a_color; gl_Position = mvp_matrix * a_position; } </code></pre>
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    1. POgluPerspective was removed in OpenGL 3.1, any replacements?
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    1. USDan
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    1. COthank you :) that opengl mathematics library seems not bad at all.
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    2. COPerfect! Thanks for sharing.
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      1. USXavier Ho
    3. COThis function doesn't work. What is xmax and ymax? They're used on the second line and not defined
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