62 lines
1.8 KiB
ReStructuredText
62 lines
1.8 KiB
ReStructuredText
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How to send vector or matrix to OpenGL like API
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==================================================
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*cglm*'s vector and matrix types are arrays. So you can send them directly to a
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function which accepts pointer. But you may got warnings for matrix because it is
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two dimensional array.
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Passing / Uniforming Matrix to OpenGL:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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**glUniformMatrix4fv** accepts float pointer, you can pass matrix to that parameter
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and it should work but with warnings. "You can pass" doesn't mean that you must pass like that.
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**Correct options:**
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Correct doesn't mean correct way to use OpenGL it is just shows correct way to pass cglm type to it.
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1. Pass first column
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---------------------
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The goal is that pass address of matrix, first element of matrix is also address of matrix,
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because it is array of vectors and vector is array of floats.
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.. code-block:: c
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mat4 matrix;
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/* ... */
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glUniformMatrix4fv(location, 1, GL_FALSE, matrix[0]);
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array of matrices:
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.. code-block:: c
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mat4 matrix;
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/* ... */
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glUniformMatrix4fv(location, count, GL_FALSE, matrix[0][0]);
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1. Cast matrix to pointer
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--------------------------
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.. code-block:: c
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mat4 matrix;
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/* ... */
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glUniformMatrix4fv(location, count, GL_FALSE, (float *)matrix);
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in this way, passing aray of matrices is same
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Passing / Uniforming Vectors to OpenGL:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You don't need to do extra thing when passing cglm vectors to OpengL or other APIs.
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Because a function like **glUniform4fv** accepts vector as pointer. cglm's vectors
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are array of floats. So you can pass it directly ot those functions:
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.. code-block:: c
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vec4 vec;
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/* ... */
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glUniform4fv(location, 1, vec);
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this show how to pass **vec4** others are same.
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