OpenGL 学习笔记-2015.4.18——立方体纹理映射-天空盒子-环境映射

标签：opengl   图形   游戏开发   c++   

#include "cubeTexture\cubeTexture.h"
#include "vbm.h"
#include "vutils.h"
#include "vmath.h"
#include "vermilion.h"

namespace cubeTexture
{
	float aspect = 800.0/600.0f;
	GLuint skybox_prog;
	GLuint object_prog;
	GLuint vao;

	GLuint cube_vbo;
	GLuint cube_element_buffer;

	GLuint tex;
	GLint skybox_rotate_loc;

	GLint object_mat_mvp_loc;
	GLint object_mat_mv_loc;
	VBObject object;

	void cubeTextureInit()
	{
		skybox_prog = glCreateProgram();
		static const char skybox_shader_vs[] =
			"#version 330 core\n"
			"\n"
			"layout (location = 0) in vec3 in_position;\n"
			"\n"
			"out vec3 tex_coord;\n"
			"\n"
			"uniform mat4 tc_rotate;\n"
			"\n"
			"void main(void)\n"
			"{\n"
			"    gl_Position = tc_rotate * vec4(in_position, 1.0);\n"
			"    tex_coord = in_position;\n"
			"}\n";
		
		static const char skybox_shader_fs[] =
			"#version 330 core\n"
			"\n"
			"in vec3 tex_coord;\n"
			"\n"
			"layout (location = 0) out vec4 color;\n"
			"\n"
			"uniform samplerCube tex;\n"
			"\n"
			"void main(void)\n"
			"{\n"
			"    color = texture(tex, tex_coord);\n"
			"}\n";
		
		vglAttachShaderSource(skybox_prog, GL_VERTEX_SHADER, skybox_shader_vs);
		vglAttachShaderSource(skybox_prog, GL_FRAGMENT_SHADER, skybox_shader_fs );

		glLinkProgram( skybox_prog );

		static const char object_shader_vs[] =
			"#version 330 core\n"
			"\n"
			"layout (location = 0) in vec4 in_position;\n"
			"layout (location = 1) in vec3 in_normal;\n"
			"\n"
			"out vec3 vs_fs_normal;\n"
			"out vec3 vs_fs_position;\n"
			"\n"
			"uniform mat4 mat_mvp;\n"
			"uniform mat4 mat_mv;\n"
			"\n"
			"void main(void)\n"
			"{\n"
			"    gl_Position = mat_mvp * in_position;\n"
			"    vs_fs_normal = mat3(mat_mv) * in_normal;\n"
			"    vs_fs_position = (mat_mv * in_position).xyz;\n"
			"}\n";
		
		static const char object_shader_fs[] =
			"#version 330 core\n"
			"\n"
			"in vec3 vs_fs_normal;\n"
			"in vec3 vs_fs_position;\n"
			"\n"
			"layout (location = 0) out vec4 color;\n"
			"\n"
			"uniform samplerCube tex;\n"
			"\n"
			"void main(void)\n"
			"{\n"
			"    vec3 tc =  reflect(vs_fs_position, normalize(vs_fs_normal));\n"//这里的原理其实是根据摄像机与观察点形成的向量（默认摄像机在(0,0,0,)）,
																				//和观察点顶点法线计算最终顶点纹理坐标。有点类似于关照反射的计算。
																				//并且这里的所有的计算也是在观察空间内计算的，因为我们之前就进行了，model view变换。
			"    color = vec4(0.3, 0.2, 0.1, 1.0) + vec4(0.97, 0.83, 0.79, 0.0) * texture(tex, tc);\n"
			"}\n";
		
		object_prog = glCreateProgram();

		vglAttachShaderSource( object_prog, GL_VERTEX_SHADER, object_shader_vs );
		vglAttachShaderSource( object_prog, GL_FRAGMENT_SHADER, object_shader_fs );

		glLinkProgram( object_prog );

		glGenBuffers( 1, &cube_vbo );
		glBindBuffer( GL_ARRAY_BUFFER, cube_vbo );

		static const GLfloat cube_vertices[] = 
		{
			-1.0f, -1.0f, -1.0f,
			-1.0f, -1.0f, 1.0f,
			-1.0f, 1.0f, -1.0f,
			-1.0f, 1.0f, 1.0f,
			1.0f, -1.0f, -1.0f,
			1.0f, -1.0f, 1.0f,
			1.0f, 1.0f, -1.0f,
			1.0f, 1.0f, 1.0f
		};

		static const GLushort cube_indices[] = 
		{
			0, 1, 2, 3, 6, 7, 4, 5,         // First strip
			2, 6, 0, 4, 1, 5, 3, 7          // Second strip
		};

		glBufferData( GL_ARRAY_BUFFER, sizeof(cube_vertices), cube_vertices, GL_STATIC_DRAW );

		glGenVertexArrays( 1, &vao );
		glBindVertexArray( vao );

		glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );
		glEnableVertexAttribArray(0);

		glGenBuffers( 1, &cube_element_buffer );
		glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, cube_element_buffer );
		glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof(cube_indices), cube_indices, GL_STATIC_DRAW );

		skybox_rotate_loc = glGetUniformLocation(skybox_prog, "tc_rotate");
		object_mat_mvp_loc = glGetUniformLocation(object_prog, "mat_mvp");
		object_mat_mv_loc = glGetUniformLocation(object_prog, "mat_mv");

		vglImageData image;

		tex = vglLoadTexture("../8edlib/media/TantolundenCube.dds", 0, &image);


		vglUnloadImage(&image);

		object.LoadFromVBM("../8edlib/media/unit_torus.vbm", 0, 1, 2 );
	}

	void cubeTextureUpdate( float delta )
	{

	}

	void cubeTextureDisplay()
	{
		static const unsigned int start_time = GetTickCount();
		float t = float((GetTickCount() - start_time)) / float(0x3FFF);
		static float time = 1.0;
		time += 0.01;
		static const vmath::vec3 X(1.0f, 0.0f, 0.0f);
		static const vmath::vec3 Y(0.0f, 1.0f, 0.0f);
		static const vmath::vec3 Z(0.0f, 0.0f, 1.0f);

		vmath::mat4 tc_matrix( vmath::mat4::identity() );

		glClearColor( 0.0f, 0.25f, 0.3f, 1.0f );
		glClearDepth( 1.0f );
		glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
		
		glEnable( GL_DEPTH_TEST );
		glDepthFunc( GL_LEQUAL );
		glDisable( GL_CULL_FACE );
		glUseProgram( skybox_prog );

		glEnable( GL_TEXTURE_CUBE_MAP_SEAMLESS );//开启时，两个面的交界处会进行双边线性采样来确定边缘像素，关闭时，将只采用单边值进行设置。

		tc_matrix = vmath::perspective( 35.0f, 1.0f / aspect, 0.1f, 100.0f ) * tc_matrix;

		glUniformMatrix4fv( skybox_rotate_loc, 1, GL_FALSE, tc_matrix );
		glBindVertexArray(vao);
		glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, cube_element_buffer );

		glDrawElements( GL_TRIANGLE_STRIP, 8, GL_UNSIGNED_SHORT, NULL );
		glDrawElements( GL_TRIANGLE_STRIP, 8, GL_UNSIGNED_SHORT, BUFFER_OFFSET( 8 * sizeof(GLushort) ) );

		glUseProgram( object_prog );

		tc_matrix = vmath::translate( vmath::vec3(0.0f, 0.0f, -4.0f) ) *
			vmath::rotate(80.0f * 3.0f * time, Y) * vmath::rotate(70.0f * 3.0f * time, Z);

		glUniformMatrix4fv( object_mat_mv_loc, 1, GL_FALSE, tc_matrix );

		tc_matrix = vmath::perspective(35.0f, 1.0f / aspect, 0.1f, 100.0f) * tc_matrix;
		glUniformMatrix4fv( object_mat_mvp_loc, 1, GL_FALSE, tc_matrix );

		glClear( GL_DEPTH_BUFFER_BIT );

		object.Render();

		GLenum e;

		e = glGetError();
	}
};

运行效果：

OpenGL 学习笔记-2015.4.18——立方体纹理映射-天空盒子-环境映射

标签：opengl   图形   游戏开发   c++   

原文地址：http://blog.csdn.net/coderling/article/details/45236967