GLImage.cc

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#include "GLImage.hh"
#include "GLContext.hh"
#include "SDLSurfacePtr.hh"
#include "MSXException.hh"
#include "Math.hh"
#include "PNG.hh"
#include "xrange.hh"
#include "endian.hh"
#include <cstdlib>
#include <SDL.h>
 
using namespace gl;
 
namespace openmsx {
 
static gl::Texture loadTexture(
        SDLSurfacePtr surface, ivec2& size)
{
        size = ivec2(surface->w, surface->h);
        // Make a copy to convert to the correct pixel format.
        // TODO instead directly load the image in the correct format.
        SDLSurfacePtr image2(size[0], size[1], 32,
                Endian::BIG ? 0xFF000000 : 0x000000FF,
                Endian::BIG ? 0x00FF0000 : 0x0000FF00,
                Endian::BIG ? 0x0000FF00 : 0x00FF0000,
                Endian::BIG ? 0x000000FF : 0xFF000000);
 
        SDL_Rect area;
        area.x = 0;
        area.y = 0;
        area.w = size[0];
        area.h = size[1];
        SDL_SetSurfaceBlendMode(surface.get(), SDL_BLENDMODE_NONE);
        SDL_BlitSurface(surface.get(), &area, image2.get(), &area);
 
        gl::Texture texture(true); // enable interpolation
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, size[0], size[1], 0,
                     GL_RGBA, GL_UNSIGNED_BYTE, image2->pixels);
        return texture;
}
 
static gl::Texture loadTexture(
        const std::string& filename, ivec2& size)
{
        SDLSurfacePtr surface(PNG::load(filename, false));
        try {
                return loadTexture(std::move(surface), size);
        } catch (MSXException& e) {
                throw MSXException("Error loading image ", filename, ": ",
                                   e.getMessage());
        }
}
 
 
GLImage::GLImage(OutputSurface& /*output*/, const std::string& filename)
        : texture(loadTexture(filename, size))
{
}
 
GLImage::GLImage(OutputSurface& /*output*/, const std::string& filename, float scalefactor)
        : texture(loadTexture(filename, size))
{
        size = trunc(vec2(size) * scalefactor);
        checkSize(size);
}
 
GLImage::GLImage(OutputSurface& /*output*/, const std::string& filename, ivec2 size_)
        : texture(loadTexture(filename, size))
{
        checkSize(size_);
        size = size_;
}
 
GLImage::GLImage(OutputSurface& /*output*/, ivec2 size_, unsigned rgba)
        : texture(gl::Null())
{
        checkSize(size_);
        size = size_;
        borderSize = 0;
        borderR = borderG = borderB = borderA = 0; // not used, but avoid (harmless) UMR
        for (auto i : xrange(4)) {
                bgR[i] = (rgba >> 24) & 0xff;
                bgG[i] = (rgba >> 16) & 0xff;
                bgB[i] = (rgba >>  8) & 0xff;
                unsigned alpha = (rgba >> 0) & 0xff;
                bgA[i] = (alpha == 255) ? 256 : alpha;
        }
        initBuffers();
}
 
GLImage::GLImage(OutputSurface& /*output*/, ivec2 size_, std::span<const unsigned, 4> rgba,
                 int borderSize_, unsigned borderRGBA)
        : texture(gl::Null())
{
        checkSize(size_);
        size = size_;
        borderSize = borderSize_;
        for (auto i : xrange(4)) {
                bgR[i] = (rgba[i] >> 24) & 0xff;
                bgG[i] = (rgba[i] >> 16) & 0xff;
                bgB[i] = (rgba[i] >>  8) & 0xff;
                unsigned alpha = (rgba[i] >> 0) & 0xff;
                bgA[i] = (alpha == 255) ? 256 : alpha;
        }
 
        borderR = (borderRGBA >> 24) & 0xff;
        borderG = (borderRGBA >> 16) & 0xff;
        borderB = (borderRGBA >>  8) & 0xff;
        unsigned alpha = (borderRGBA >> 0) & 0xff;
        borderA = (alpha == 255) ? 256 : alpha;
 
        initBuffers();
}
 
GLImage::GLImage(OutputSurface& /*output*/, SDLSurfacePtr image)
        : texture(loadTexture(std::move(image), size))
{
}
 
void GLImage::initBuffers()
{
        // border
        uint8_t indices[10] = {4, 0, 5, 1, 6, 2, 7, 3, 4, 0};
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementsBuffer.get());
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
 
void GLImage::draw(OutputSurface& /*output*/, ivec2 pos, uint8_t r, uint8_t g, uint8_t b, uint8_t alpha)
{
        // 4-----------------7
        // |                 |
        // |   0---------3   |
        // |   |         |   |
        // |   |         |   |
        // |   1-------- 2   |
        // |                 |
        // 5-----------------6
        int bx = (size[0] > 0) ? borderSize : -borderSize;
        int by = (size[1] > 0) ? borderSize : -borderSize;
        ivec2 positions[8] = {
                pos + ivec2(        + bx,         + by), // 0
                pos + ivec2(        + bx, size[1] - by), // 1
                pos + ivec2(size[0] - bx, size[1] - by), // 2
                pos + ivec2(size[0] - bx,         + by), // 3
                pos + ivec2(0           , 0           ), // 4
                pos + ivec2(0           , size[1]     ), // 5
                pos + ivec2(size[0]     , size[1]     ), // 6
                pos + ivec2(size[0]     , 0           ), // 7
        };
 
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
        glBindBuffer(GL_ARRAY_BUFFER, vbo[0].get());
        glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, GL_STREAM_DRAW);
 
        if (texture.get()) {
                vec2 tex[4] = {
                        vec2(0.0f, 0.0f),
                        vec2(0.0f, 1.0f),
                        vec2(1.0f, 1.0f),
                        vec2(1.0f, 0.0f),
                };
 
                gl::context->progTex.activate();
                glUniform4f(gl::context->unifTexColor,
                            r / 255.0f, g / 255.0f, b / 255.0f, alpha / 255.0f);
                glUniformMatrix4fv(gl::context->unifTexMvp, 1, GL_FALSE,
                                   &gl::context->pixelMvp[0][0]);
                const ivec2* offset = nullptr;
                glVertexAttribPointer(0, 2, GL_INT, GL_FALSE, 0, offset + 4);
                glEnableVertexAttribArray(0);
                glBindBuffer(GL_ARRAY_BUFFER, vbo[1].get());
                glBufferData(GL_ARRAY_BUFFER, sizeof(tex), tex, GL_STREAM_DRAW);
                glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
                glEnableVertexAttribArray(1);
                texture.bind();
                glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
                glDisableVertexAttribArray(1);
                glDisableVertexAttribArray(0);
        } else {
                assert(r == 255);
                assert(g == 255);
                assert(b == 255);
                gl::context->progFill.activate();
                glUniformMatrix4fv(gl::context->unifFillMvp, 1, GL_FALSE,
                                   &gl::context->pixelMvp[0][0]);
                glVertexAttribPointer(0, 2, GL_INT, GL_FALSE, 0, nullptr);
                glEnableVertexAttribArray(0);
                glVertexAttrib4f(1, borderR / 255.0f, borderG / 255.0f, borderB / 255.0f,
                                (borderA * alpha) / (255.0f * 255.0f));
 
                if ((2 * borderSize >= abs(size[0])) ||
                    (2 * borderSize >= abs(size[1]))) {
                        // only border
                        glDrawArrays(GL_TRIANGLE_FAN, 4, 4);
                } else {
                        // border
                        if (borderSize > 0) {
                                glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementsBuffer.get());
                                glDrawElements(GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_BYTE, nullptr);
                                glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
                        }
 
                        // interior
                        uint8_t col[4][4] = {
                                { bgR[0], bgG[0], bgB[0], uint8_t((bgA[0] * alpha) / 256) },
                                { bgR[2], bgG[2], bgB[2], uint8_t((bgA[2] * alpha) / 256) },
                                { bgR[3], bgG[3], bgB[3], uint8_t((bgA[3] * alpha) / 256) },
                                { bgR[1], bgG[1], bgB[1], uint8_t((bgA[1] * alpha) / 256) },
                        };
                        glBindBuffer(GL_ARRAY_BUFFER, vbo[2].get());
                        glBufferData(GL_ARRAY_BUFFER, sizeof(col), col, GL_STREAM_DRAW);
                        glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);
                        glEnableVertexAttribArray(1);
                        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
                        glDisableVertexAttribArray(1);
                }
                glDisableVertexAttribArray(0);
        }
        glDisableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glDisable(GL_BLEND);
}
 
} // namespace openmsx