32 lines
823 B
C
32 lines
823 B
C
#include <c3d/maths.h>
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void Mtx_OrthoTilt(C3D_Mtx* mtx, float left, float right, float bottom, float top, float near, float far)
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{
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C3D_Mtx mp;
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Mtx_Zeros(&mp);
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// Build standard orthogonal projection matrix
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mp.r[0].x = 2.0f / (right - left);
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mp.r[0].w = (left + right) / (left - right);
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mp.r[1].y = 2.0f / (top - bottom);
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mp.r[1].w = (bottom + top) / (bottom - top);
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mp.r[2].z = 2.0f / (near - far);
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mp.r[2].w = (far + near) / (far - near);
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mp.r[3].w = 1.0f;
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// Fix depth range to [-1, 0]
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C3D_Mtx mp2, mp3;
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Mtx_Identity(&mp2);
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mp2.r[2].z = 0.5;
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mp2.r[2].w = -0.5;
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Mtx_Multiply(&mp3, &mp2, &mp);
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// Fix the 3DS screens' orientation by swapping the X and Y axis
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Mtx_Identity(&mp2);
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mp2.r[0].x = 0.0;
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mp2.r[0].y = 1.0;
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mp2.r[1].x = -1.0; // flipped
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mp2.r[1].y = 0.0;
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Mtx_Multiply(mtx, &mp2, &mp3);
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}
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