Add ortographic camera

hex_math.h

@@ -1,10 +1,26 @@
 #define _USE_MATH_DEFINES // for finding things like M_PI in Windows build
 #include <math.h>
 #include <stdint.h>
+#include "hex_debug.h"
 /* Types */
 typedef float _v2f __attribute__((matrix_type(1,2)));
 typedef float _v3f __attribute__((matrix_type(1,3)));
 typedef float _v4f __attribute__((matrix_type(1,4)));
+typedef float _mat4 __attribute__((matrix_type(4,4)));
+
+typedef struct {
+    union {
+        struct {
+            float first;
+            float second;
+        };
+        _v2f v2f;
+        struct {
+            float x;
+            float y;
+        };
+    };
+} vec2f;
 
 typedef struct {
     union {
@@ -36,6 +52,37 @@ typedef struct {
     };
 } vec4f;
 
+/* Row-major matrix, make sure to pass it to OpenGL trasposed */
+typedef struct {
+    union {
+        _mat4 m4f;
+        struct {
+            float a0;
+            float a1;
+            float a2;
+            float a3;
+            float b0;
+            float b1;
+            float b2;
+            float b3;
+            float c0;
+            float c1;
+            float c2;
+            float c3;
+            float d0;
+            float d1;
+            float d2;
+            float d3;
+        };
+        struct {
+            vec4f row0;
+            vec4f row1;
+            vec4f row2;
+            vec4f row3;
+        };
+    };
+} mat4f;
+
 typedef struct {
     vec4f position;          // center pos
     float radius;            // side length
@@ -44,7 +91,6 @@ typedef struct {
     uint32_t vbo;
     float vertices[7*3];     // 7 vert per hex
     unsigned int indices[6*3];   // 6 triangles to render a hex
-
 } hex_t;
 
 typedef struct {
@@ -53,7 +99,17 @@ typedef struct {
     uint32_t columns;
 } hexgrid_t;
 
+typedef struct {
+    float left;
+    float right;
+    float top;
+    float bottom;
+    float near;
+    float far;
+} camera_t;
+
 _Static_assert(sizeof(vec4f) == sizeof(float) * 4, "Bad vector size");
+_Static_assert(sizeof(mat4f) == sizeof(float) * 16, "Bad matrix size");
 
 /* Functions */
 double sint(double turns)
@@ -65,3 +121,32 @@ double cost(double turns)
 {
     return cos(turns*2*M_PI);
 }
+
+mat4f ortho_matrix(float left, float right, float top, float bottom, float near, float far, float width, float height)
+{
+    // Invert Y coord
+    float aux;
+    aux = bottom;
+    bottom = top;
+    top = aux;
+
+    // Scale and move to [-1,1]
+    left = (left*2 - width)/width;
+    right = (right*2 - width)/width;
+
+    top = (top*2 - height)/height;
+    bottom = (bottom*2 - height)/height;
+
+
+
+    mat4f matrix = {};
+    matrix.a0 = 2/(right - left);
+    matrix.a3 = -((right + left)/(right - left));
+    matrix.b1 = 2/(top - bottom);
+    matrix.b3 = -((top + bottom)/(top - bottom));
+    matrix.c2 = -2/(far - near);
+    matrix.c3 = -((far + near)/(far - near));
+    matrix.d3 = 1;
+
+    return matrix;
+}