medfall

commit f7bab989ed3ccea09b13252b1ac75b80ce122491
parent 5e60b92fe7c2bd6d64fe0416386fea14c3482a6e
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sat Sep 10 19:40:31 -0700

Add immediate_arrow

Diffstat:
immediate.cc
 | 
88
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
immediate.h
 | 
3
+++
2 files changed, 91 insertions(+), 0 deletions(-)
diff --git a/immediate.cc b/immediate.cc
@@ -126,6 +126,94 @@ void immediate_aabb( ImmediateContext * ctx, glm::vec3 mins, glm::vec3 maxs, glm
 	immediate_triangle( ctx, v7, v6, v2, colour );
 }
 
+static glm::mat3 about_with_sin_cos( glm::vec3 axis, float s, float c ) {
+	return glm::mat3(
+		axis.x * axis.x + ( 1.0 - axis.x * axis.x ) * c,
+		axis.x * axis.y * ( 1.0 - c ) - axis.z * s,
+		axis.x * axis.z * ( 1.0 - c ) + axis.y * s,
+		axis.y * axis.x * ( 1.0 - c ) + axis.z * s,
+		axis.y * axis.y + ( 1.0 - axis.y * axis.y ) * c,
+		axis.y * axis.z * ( 1.0 - c ) - axis.x * s,
+		axis.z * axis.x * ( 1.0 - c ) - axis.y * s,
+		axis.z * axis.y * ( 1.0 - c ) + axis.x * s,
+		axis.z * axis.z + ( 1.0 - axis.z * axis.z ) * c
+	);
+}
+
+static glm::mat3 rotation_between( glm::vec3 from, glm::vec3 to ) {
+	if( from == to ) return glm::mat3();
+	if( from == -to ) return -glm::mat3();
+
+	glm::vec3 axis = glm::normalize( glm::cross( from, to ) );
+	float cos_theta = glm::dot( from, to );
+	// TODO: why is this -?????
+	float sin_theta = -sqrtf( 1.0f - cos_theta * cos_theta );
+
+	return about_with_sin_cos( axis, sin_theta, cos_theta );
+}
+
+void immediate_arrow( ImmediateContext * ctx, glm::vec3 origin, glm::vec3 direction, float length, glm::vec4 colour ) {
+	glm::vec3 v[] = {
+		// base of stick
+		glm::vec3( -0.05, -0.05, 0 ),
+		glm::vec3( 0.05, -0.05, 0 ),
+		glm::vec3( -0.05, 0.05, 0 ),
+		glm::vec3( 0.05, 0.05, 0 ),
+
+		// top of stick
+		glm::vec3( -0.05, -0.05, 0.6 ),
+		glm::vec3( 0.05, -0.05, 0.6 ),
+		glm::vec3( -0.05, 0.05, 0.6 ),
+		glm::vec3( 0.05, 0.05, 0.6 ),
+
+		// point
+		glm::vec3( 0, 0, 1 ),
+		glm::vec3( 0, 0, 0.6 ),
+	};
+
+	const size_t CONE_SUBDIVISIONS = 8;
+	glm::vec3 cone[ CONE_SUBDIVISIONS ];
+
+	// TODO: do the fast sin/cos thing
+	// TODO: make a helper function to do it that fills in an array of floats
+	for( size_t i = 0; i < array_count( cone ); i++ ) {
+		float s = sinf( float( i ) / float( array_count( cone ) ) * 2.0f * M_PI );
+		float c = cosf( float( i ) / float( array_count( cone ) ) * 2.0f * M_PI );
+
+		cone[ i ] = glm::vec3( 0.2f * c, 0.2f * s, 0.6 );
+	}
+
+	glm::mat3 rot = rotation_between( glm::vec3( 0, 0, 1 ), glm::normalize( direction ) );
+
+	for( size_t i = 0; i < array_count( v ); i++ ) {
+		v[ i ] = ( rot * v[ i ] ) * length + origin;
+	}
+	for( size_t i = 0; i < array_count( cone ); i++ ) {
+		cone[ i ] = ( rot * cone[ i ] ) * length + origin;
+	}
+
+	immediate_triangle( ctx, v[ 0 ], v[ 1 ], v[ 2 ], colour ); // bottom
+	immediate_triangle( ctx, v[ 1 ], v[ 3 ], v[ 2 ], colour );
+	immediate_triangle( ctx, v[ 4 ], v[ 6 ], v[ 5 ], colour ); // top
+	immediate_triangle( ctx, v[ 6 ], v[ 7 ], v[ 5 ], colour );
+	immediate_triangle( ctx, v[ 2 ], v[ 6 ], v[ 0 ], colour ); // left
+	immediate_triangle( ctx, v[ 6 ], v[ 4 ], v[ 0 ], colour );
+	immediate_triangle( ctx, v[ 1 ], v[ 5 ], v[ 3 ], colour ); // right
+	immediate_triangle( ctx, v[ 5 ], v[ 7 ], v[ 3 ], colour );
+	immediate_triangle( ctx, v[ 0 ], v[ 4 ], v[ 1 ], colour ); // front
+	immediate_triangle( ctx, v[ 4 ], v[ 5 ], v[ 1 ], colour );
+	immediate_triangle( ctx, v[ 3 ], v[ 7 ], v[ 2 ], colour ); // back
+	immediate_triangle( ctx, v[ 7 ], v[ 6 ], v[ 2 ], colour );
+
+	for( size_t i = 0; i < array_count( cone ); i++ ) {
+		immediate_triangle( ctx, v[ 8 ], cone[ ( i + 1 ) % array_count( cone ) ], cone[ i ], colour );
+	}
+
+	for( size_t i = 0; i < array_count( cone ); i++ ) {
+		immediate_triangle( ctx, v[ 9 ], cone[ i ], cone[ ( i + 1 ) % array_count( cone ) ], colour );
+	}
+}
+
 void immediate_render(
 	const ImmediateContext * ctx,
 	GLint at_position, GLint at_colour,
diff --git a/immediate.h b/immediate.h
@@ -34,6 +34,9 @@ void immediate_sphere( ImmediateContext * ctx,
 void immediate_aabb( ImmediateContext * ctx,
 	glm::vec3 mins, glm::vec3 maxs, glm::vec4 colour );
 
+void immediate_arrow( ImmediateContext * ctx, glm::vec3 origin,
+	glm::vec3 direction, float length, glm::vec4 colour );
+
 void immediate_render( const ImmediateContext * ctx,
 	GLint at_position, GLint at_colour,
 	bool textured = false, GLint at_uv = 0, GLint un_texture = 0 );