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/* PointerShader.cpp
Copyright (c) 2014 by Michael Zahniser
Endless Sky is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later version.
Endless Sky is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "PointerShader.h"
#include "../Color.h"
#include "../GameData.h"
#include "../Point.h"
#include "../Screen.h"
#include "Shader.h"
#include <stdexcept>
using namespace std;
namespace {
const Shader *shader;
GLint scaleI;
GLint centerI;
GLint angleI;
GLint sizeI;
GLint offsetI;
GLint colorI;
GLuint vao;
GLuint vbo;
}
void PointerShader::Init()
{
shader = GameData::Shaders().Get("pointer");
if(!shader->Object())
throw std::runtime_error("Could not find pointer shader!");
scaleI = shader->Uniform("scale");
centerI = shader->Uniform("center");
angleI = shader->Uniform("angle");
sizeI = shader->Uniform("size");
offsetI = shader->Uniform("offset");
colorI = shader->Uniform("color");
// Generate the vertex data for drawing sprites.
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
glGenBuffers(1, &vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
GLfloat vertexData[] = {
0.f, 0.f,
0.f, 1.f,
1.f, 0.f,
};
glBufferData(GL_ARRAY_BUFFER, sizeof(vertexData), vertexData, GL_STATIC_DRAW);
glEnableVertexAttribArray(shader->Attrib("vert"));
glVertexAttribPointer(shader->Attrib("vert"), 2, GL_FLOAT, GL_FALSE, 2 * sizeof(GLfloat), nullptr);
// unbind the VBO and VAO
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
void PointerShader::Draw(const Point ¢er, const Point &angle,
float width, float height, float offset, const Color &color)
{
Bind();
Add(center, angle, width, height, offset, color);
Unbind();
}
void PointerShader::Bind()
{
if(!shader || !shader->Object())
throw runtime_error("PointerShader: Bind() called before Init().");
glUseProgram(shader->Object());
glBindVertexArray(vao);
GLfloat scale[2] = {2.f / Screen::Width(), -2.f / Screen::Height()};
glUniform2fv(scaleI, 1, scale);
}
void PointerShader::Add(const Point ¢er, const Point &angle,
float width, float height, float offset, const Color &color)
{
GLfloat c[2] = {static_cast<float>(center.X()), static_cast<float>(center.Y())};
glUniform2fv(centerI, 1, c);
GLfloat a[2] = {static_cast<float>(angle.X()), static_cast<float>(angle.Y())};
glUniform2fv(angleI, 1, a);
GLfloat size[2] = {width, height};
glUniform2fv(sizeI, 1, size);
glUniform1f(offsetI, offset);
glUniform4fv(colorI, 1, color.Get());
glDrawArrays(GL_TRIANGLES, 0, 3);
}
void PointerShader::Unbind()
{
glBindVertexArray(0);
glUseProgram(0);
}
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