medfall

commit 8e369caeb240febddc789fc1dca7b4f7c48a4a70
parent 5ee37304fa4260a4ba6319f9a2f63b25ad5b4a35
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sun Jan 31 11:27:14 +0000

Add skybox code so btt builds

Diffstat:
skybox.cc
 | 
115
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
skybox.h
 | 
21
+++++++++++++++++++++
2 files changed, 136 insertions(+), 0 deletions(-)
diff --git a/skybox.cc b/skybox.cc
@@ -0,0 +1,115 @@
+#include "platform_opengl.h"
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
+#include "game.h"
+#include "intrinsics.h"
+
+/*
+ *  0------1
+ *  |`.    |`.    y
+ *  |  `2--+---3   \_x
+ *  |   |  |   |   |
+ *  4---+--5   |   -z
+ *   `. |   `. |
+ *     `6------7
+ */
+
+static const GLchar * const vert_src = GLSL(
+	in vec3 position;
+
+	out vec3 direction;
+
+	uniform mat4 VP;
+
+	void main() {
+		vec4 world_pos = VP * vec4( position, 1.0 );
+		gl_Position = world_pos.xyww;
+		direction = position;
+	}
+);
+
+static const GLchar * frag_src = GLSL(
+	in vec3 direction;
+
+	out vec4 screen_colour;
+
+	void main() {
+		screen_colour = vec4( 1.0, 0.0, 0.0, 1.0 );
+	}
+);
+
+static glm::vec3 cube_verts[] = {
+	glm::vec3( -1.0f,  1.0f,  1.0f ),
+	glm::vec3(  1.0f,  1.0f,  1.0f ),
+	glm::vec3( -1.0f, -1.0f,  1.0f ),
+	glm::vec3(  1.0f, -1.0f,  1.0f ),
+	glm::vec3( -1.0f,  1.0f, -1.0f ),
+	glm::vec3(  1.0f,  1.0f, -1.0f ),
+	glm::vec3( -1.0f, -1.0f, -1.0f ),
+	glm::vec3(  1.0f, -1.0f, -1.0f ),
+};
+
+static GLuint cube_indices[] = { 7, 6, 3, 2, 0, 6, 4, 7, 5, 3, 1, 0, 5, 4 };
+
+void skybox_init( Skybox * skybox ) {
+	skybox->shader = compile_shader( vert_src, frag_src, "screen_colour" );
+	skybox->at_position = glGetAttribLocation( skybox->shader, "position" );
+	skybox->un_vp = glGetUniformLocation( skybox->shader, "vp" );
+
+	glGenVertexArrays( 1, &skybox->vao );
+	glBindVertexArray( skybox->vao );
+
+	glGenBuffers( 1, &skybox->vbo );
+	glBindBuffer( GL_ARRAY_BUFFER, skybox->vbo );
+	glBufferData( GL_ARRAY_BUFFER, sizeof( cube_verts ), cube_verts, GL_STATIC_DRAW );
+	glEnableVertexAttribArray( skybox->at_position );
+	glVertexAttribPointer( skybox->at_position, 3, GL_FLOAT, GL_FALSE, sizeof( glm::vec3 ), 0 );
+
+	glGenBuffers( 1, &skybox->ebo );
+	glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, skybox->ebo );
+	glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof( cube_indices ), cube_indices, GL_STATIC_DRAW );
+
+	glBindVertexArray( 0 );
+}
+
+static const glm::mat4 P( glm::perspective( glm::radians( 120.0f ), ( float ) WIDTH / ( float ) HEIGHT, NEAR, FAR ) );
+
+void skybox_render( const Skybox * skybox, const glm::vec3 & angles ) {
+	glDisable( GL_CULL_FACE );
+	for( size_t i = 0; i < array_count( cube_verts ); i++ ) {
+		glm::vec4 x = P * glm::vec4( cube_verts[ i ], 1.0f );
+		printf( "%d: %.3f %.3f %.3f %.3f\n", i, x.x, x.y, x.z, x.w );
+	}
+	glm::mat4 vp = glm::rotate(
+		glm::rotate(
+			P,
+			angles.x,
+			glm::vec3( 1, 0, 0 )
+		),
+		angles.y,
+		glm::vec3( 0, 0, 1 )
+	);
+
+	glUseProgram( skybox->shader );
+	glBindVertexArray( skybox->vao );
+
+	glUniformMatrix4fv( skybox->un_vp, 1, GL_FALSE, glm::value_ptr( vp ) );
+
+	glDrawElements( GL_TRIANGLE_STRIP, array_count( cube_indices ), GL_UNSIGNED_INT, 0 );
+
+	glBindVertexArray( 0 );
+	glUseProgram( 0 );
+	glEnable( GL_CULL_FACE );
+}
+
+void skybox_destroy( Skybox * skybox ) {
+	glDeleteBuffers( 1, &skybox->ebo );
+	glDeleteBuffers( 1, &skybox->vbo );
+	glDeleteVertexArrays( 1, &skybox->vao );
+
+	glDeleteProgram( skybox->shader );
+
+	// *skybox = { };
+}
diff --git a/skybox.h b/skybox.h
@@ -0,0 +1,21 @@
+#ifndef _SKYBOX_H_
+#define _SKYBOX_H_
+
+#include "platform_opengl.h"
+#include <glm/glm.hpp>
+
+struct Skybox {
+	GLuint shader;
+	GLuint at_position;
+	GLuint un_vp;
+
+	GLuint vao;
+	GLuint vbo;
+	GLuint ebo;
+};
+
+void skybox_init( Skybox * skybox );
+void skybox_render( const Skybox * skybox, const glm::vec3 & angles );
+void skybox_destroy( Skybox * skybox );
+
+#endif // _SKYBOX_H_