+// Copyright (C) 2021 Harry Godden (hgn) - All Rights Reserved
+
+SHADER_DEFINE( vg_line_shader,
+
+ // VERTEX
+ "layout (location=0) in vec2 a_co;"
+ "layout (location=1) in vec4 a_colour;"
+ "uniform mat3 uPv;"
+ ""
+ "out vec4 s_colour;"
+ ""
+ "void main()"
+ "{"
+ " vec4 vert_pos = vec4( uPv * vec3( a_co, 1.0 ), 1.0 );"
+ " s_colour = a_colour;"
+ " gl_Position = vert_pos;"
+ "}",
+
+ // FRAGMENT
+ "out vec4 FragColor;"
+ ""
+ "in vec4 s_colour;"
+ ""
+ "void main()"
+ "{"
+ " FragColor = s_colour;"
+ "}"
+ ,
+ UNIFORMS({ "uPv" })
+)
+
+struct
+{
+ struct vg_lines_vert
+ {
+ v2f co;
+ u32 colour;
+ }
+ *buffer;
+
+ GLuint vao, vbo;
+ u32 draw_idx, cap, buffer_size;
+}
+vg_lines;
+
+static void vg_lines_init(void)
+{
+ SHADER_INIT( vg_line_shader );
+
+ glGenVertexArrays( 1, &vg_lines.vao );
+ glGenBuffers( 1, &vg_lines.vbo );
+ glBindVertexArray( vg_lines.vao );
+
+ glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
+
+ vg_lines.cap = 10000;
+ vg_lines.buffer_size = vg_lines.cap * sizeof( struct vg_lines_vert );
+
+ glBufferData( GL_ARRAY_BUFFER, vg_lines.buffer_size, NULL, GL_DYNAMIC_DRAW );
+ glBindVertexArray( vg_lines.vao );
+
+ glVertexAttribPointer(
+ 0,
+ sizeof( vg_lines.buffer[0].co ) / sizeof(float),
+ GL_FLOAT,
+ GL_FALSE,
+ sizeof( struct vg_lines_vert ),
+ (void *)0
+ );
+ glEnableVertexAttribArray( 0 );
+
+ glVertexAttribPointer(
+ 1,
+ 4,
+ GL_UNSIGNED_BYTE,
+ GL_TRUE,
+ sizeof( struct vg_lines_vert ),
+ (void*)(offsetof( struct vg_lines_vert, colour ))
+ );
+ glEnableVertexAttribArray( 1 );
+ vg_lines.buffer = malloc( vg_lines.buffer_size );
+}
+
+static void vg_lines_free(void)
+{
+ glDeleteVertexArrays( 1, &vg_lines.vao );
+ glDeleteBuffers( 1, &vg_lines.vbo );
+
+ free( vg_lines.buffer );
+}
+
+static void vg_lines_drawall(float* projection)
+{
+ SHADER_USE( vg_line_shader );
+ glUniformMatrix3fv( SHADER_UNIFORM( vg_line_shader, "uPv" ), 1, GL_FALSE, projection );
+
+ glBindVertexArray( vg_lines.vao );
+ glBindBuffer( GL_ARRAY_BUFFER, vg_lines.vbo );
+
+ glBufferSubData( GL_ARRAY_BUFFER, 0, vg_lines.draw_idx * sizeof(struct vg_lines_vert), vg_lines.buffer );
+ glEnable( GL_BLEND );
+ glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
+ glBlendEquation( GL_FUNC_ADD );
+
+ glDrawArrays( GL_LINES, 0, vg_lines.draw_idx );
+
+ glDisable( GL_BLEND );
+ vg_lines.draw_idx = 0;
+}
+
+static void vg_line2( v2f from, v2f to, u32 fc, u32 tc )
+{
+ struct vg_lines_vert *v = vg_lines.buffer + vg_lines.draw_idx;
+ v2_copy( from, v[0].co );
+ v2_copy( to, v[1].co );
+ v[0].colour = fc;
+ v[1].colour = tc;
+
+ vg_lines.draw_idx += 2;
+}
+
+static void vg_line( v2f from, v2f to, u32 colour )
+{
+ vg_line2( from, to, colour, colour );
+}
+
+static void vg_line_box( v2f min, v2f max, u32 colour )
+{
+ vg_line( min, (v2f){min[0],max[1]}, colour );
+ vg_line( (v2f){min[0],max[1]}, max, colour );
+ vg_line( max, (v2f){max[0],min[1]}, colour );
+ vg_line( (v2f){max[0],min[1]}, min, colour );
+}