【发布时间】：2016-03-06 23:41:28
【问题描述】：
我已经有一段时间没有写过一些图形编程了，我已经盯着这个看了很长一段时间了，不知道我做错了什么。
这就是我创建纹理的方式。
GLuint create_texture(const char* filename) {
SDL_Surface* surface;
GLenum tex_format;
GLint num_colors;
GLuint tex_id;
char* file_path;
file_path = get_resource(filename);
surface = IMG_Load(file_path);
if (!surface) {
SDL_Log("failed to create surface\n");
SDL_Quit();
return -1;
} else {
if ((surface->w & (surface->w - 1)) != 0) {
SDL_Log("image { %s } width is not power of 2\n", filename);
}
if ((surface->h & (surface->h - 1)) != 0) {
SDL_Log("image { %s } height is not power of 2\n", filename);
}
num_colors = surface->format->BytesPerPixel;
if (num_colors == 4) {
if (surface->format->Rmask == 0x000000ff)
tex_format = GL_RGBA;
else
tex_format = GL_BGRA;
}
if (num_colors == 3) {
if (surface->format->Rmask == 0x000000ff)
tex_format = GL_RGB;
else
tex_format = GL_BGR;
} else {
SDL_Log("pixel image format shouldn't get here! Quitting\n");
SDL_Quit();
};
glGenTextures(1, &tex_id);
glBindTexture(GL_TEXTURE_2D, tex_id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, tex_format, surface->w, surface->h, 0,
tex_format, GL_UNSIGNED_BYTE, surface->pixels);
}
if (surface) SDL_FreeSurface(surface);
free(file_path);
return tex_id;
}
上面的这段代码可以正常加载图像数据。
顶点着色器
#version 330 core
layout (location = 0) in vec3 a_pos;
layout (location = 1) in vec4 a_col;
layout (location = 2) in vec2 a_tex;
uniform mat4 u_mvp_mat;
uniform mat4 u_mod_mat;
uniform mat4 u_view_mat;
uniform mat4 u_proj_mat;
out vec4 f_color;
out vec2 f_tex;
void main()
{
gl_Position = u_mvp_mat * vec4(a_pos, 1.0);
f_tex = a_tex;
f_color = a_col;
}
片段着色器。
#version 330 core
in vec4 f_color;
out vec4 o_color;
in vec2 f_tex;
uniform sampler2D u_sprite_tex;
void main (void)
{
o_color = f_color;
o_color = texture(u_sprite_tex, f_tex);
}
这就是我设置 VBO 的方式
quad = ren2d_new(); //just a wrapper around a quad or two tri.
ren2d_set_tint(quad, 0, 1, 0, 1); //setting the color to green
pos_loc = get_attrib_location(ce_get_default_shader(), "a_pos");
col_loc = get_attrib_location(ce_get_default_shader(), "a_col");
mvp_matrix_loc = get_uniform_location(ce_get_default_shader(), "u_mvp_mat");
model_mat_loc = get_uniform_location(ce_get_default_shader(), "u_mod_mat");
view_mat_loc = get_uniform_location(ce_get_default_shader(), "u_view_mat");
proj_matrix_loc =
get_uniform_location(ce_get_default_shader(), "u_proj_mat");
tex_loc = get_uniform_location(ce_get_default_shader(), "u_sprite_tex");
camera = cam_2d_new(ce_get_width(), ce_get_height());
model_mat = mat4_identity();
mat4_scale(model_mat, 128, 128, 1);
tex_id = create_texture("test.png");
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glGenBuffers(1, &vert_buff);
glBindBuffer(GL_ARRAY_BUFFER, vert_buff);
glBufferData(GL_ARRAY_BUFFER, sizeof(quad->vertices), quad->vertices,
GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenBuffers(1, &col_buff);
glBindBuffer(GL_ARRAY_BUFFER, col_buff);
glBufferData(GL_ARRAY_BUFFER, sizeof(quad->colors), quad->colors,
GL_STATIC_DRAW);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(1);
glVertexAttribPointer(2, 4, GL_FLOAT, GL_FALSE, sizeof(quad->tex_coords),
quad->tex_coords);
glEnableVertexAttribArray(2);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glGenBuffers(1, &ind_buff);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ind_buff);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(quad->indices), quad->indices,
GL_STATIC_DRAW);
glBindVertexArray(0);
这是我的渲染函数：
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//could my texturing problems be here?
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tex_id);
glUniform1i(tex_loc, 0);
glUseProgram(ce_get_default_shader()->shader_program);
glBindVertexArray(vao);
//excuse the silly names
ce_get_view_matrices(&vview_mat, &pproj_mat, &mmvp_mat);
mat4_multi(&mmvp_mat, &vview_mat, model_mat);
mat4_multi(&mmvp_mat, &pproj_mat, &mmvp_mat);
glUniformMatrix4fv(mvp_matrix_loc, 1, GL_FALSE, mat4_get_data(&mmvp_mat));
glUniformMatrix4fv(model_mat_loc, 1, GL_FALSE, mat4_get_data(model_mat));
glUniformMatrix4fv(view_mat_loc, 1, GL_FALSE, mat4_get_data(&vview_mat));
glUniformMatrix4fv(proj_matrix_loc, 1, GL_FALSE, mat4_get_data(&pproj_mat));
glDrawElements(GL_TRIANGLES, quad->vertex_count, GL_UNSIGNED_SHORT, 0);
glBindVertexArray(0);
我只是得到一个黑色的四边形。我无法追踪它，我已经盯着它看了好几个小时了。
像这样在片段着色器中做一些非常基本的测试。
#version 330 core
in vec4 f_color;
out vec4 o_color;
in vec2 f_tex;
uniform sampler2D u_sprite_tex;
void main (void)
{
//o_color = f_color;
vec4 c;
if(f_tex.y == 1.0) { c = vec4(1.0, 0.0, 0.0, 1.0); }
if(f_tex.y == 0.0) { c = vec4(0.0, 0.0, 1.0, 1.0); }
o_color = c;
o_color = texture(u_sprite_tex, f_tex);
}
我的四边形在 x 和 y 轴上都是蓝色的。这似乎是在 0.0 中传入的唯一值没有意义。
【问题讨论】：
标签： c opengl texture-mapping